CIHM Microfiche Series (IMonographs) ICIMH Collection de microfiches (monographies) Canadian Instituta for Historicai Microraproductions / Institut Canadian da microraproductiona historiquaa k Technical and Bibliographic Notes / Notes techniques et bibliographiques The Institute has attempted to obtain the best original copy available for filming. Features of this copy which nnay be bibliographlcaliy unique, which may alter any of the images in the reproduction, or which may significantly change the usual method of filming are chedwd below. D D D D Coloured covers / Couverture de couleur Covers damaged / Couverture endommagte Covers restored and/or laminated / Couverture restaurte et/ou pellicuite Cover title missing / Le titre de couverture manque I Coloured maps / Cartes g^ographiques en couleur □ Coloured ink (i.e. other than blue or black) / Encre de couleur (i.e. autre que bleue ou noire) □ Coloured plates and/or illustrattons / Planches et/ou illustrations en couleur Bound with other material / Reli6 avec d'autres documents Only edition available / Seule Mition disponible Tight binding may cause shadows or distortion along Interior margin / La rellure serr6e peut causer de I'ombre ou de la dlstorslon le long de la marge Int^rieure. Blank leaves added during restorations may appear within the text. Whenever possible, these have been omitted from filming / Use peut que certalnes pages blanches ajout^es lors d'une restauration apparaissent dans le texte, mals, lorsque cela 6tait possible, ces pages n'ont pas 6t6 film6es. Additional comments / Commentalres suppl6mentalres: L'Instltut a rrtcrofilmA le meilleur exemplaire qu'il lul a M6 possible de se procurer. Les details de cet exem- plaire qui sont peut-#tre unk|ues du point de vue bibll- ograpNque, qui peuvent nradifier une image reproduite, ou qui peuvent exiger une modifk^tkMi dans la metho- ds nomMie de filmage sont indkiute ci-dessous. I I Cotoured pages/ Pages de couleur I I Pages damaged/ Pages endommag^es I I Pages restored and/or laminated / Pages restaurtos et/ou pellk:ul6es Pages discotoured, stained or foxed / Pages dteok>r6es, tachetdes ou pk:|utes I I Pages detached/ Pages ddtachdes \V\ Showthrough/ Transparence I I Quality of print varies / D D D Quality indgale de I'impression Includes supplementary material / Comprend du matdriel suppl^mentaire Pages wholly or partially obscured by errata slips, tissues, etc., have been refilnied to ensure the best possible image / Les pages totalement ou partlellement obscurcies par un feulllet d'enata, une pelure, etc., ont 6\6 filmtes k nouveau de fa^on k obtenir la mellleure image possible. Opposing pages with varying colouration or discokiurations are filmed twtee to ensure the best possible image / Les pages s'opposant ayant des colorations variables ou des decolorations sont fllmtes deux fols afln d'obtenir la mellleure Image possible. D This KMn is filnwd at tiM raduetion ratio dMckMl below / C« docuimnt Mt fUm4 Ml tMix d* rMuction imli<|irf cl-dHtoua. lOx 14x 18x 22x 26x SOx 12x 16x 20x 24x 28x 32x TiM eepv fNfiMd hun hat bMn raproduead thanks to tha ganareaity «f : Library L'axamplaira filmi fut raproduit grlea k la ginaroaitA da: Eiwrgi*, afiMs at BfblfetMqiw eantrala quality lagibiHty Tha ifnagaa appaaring hafa ara tha poaalhia eonsidarifig tha eonditien of t^« original copy and in iiaaping fHniing coniraot apaoificationa. Original eopiaa in printad p a p ar eovara ara fNmad baginning with tha front covar and anding on tha last paga wHh a printad or iHuatratad impraa- tion. or tha back eovar whan appropriata. All othar original coplaa ara fiimad baginning on tha first paga with a printad or IHuatratad impraa* •Ion. and anding on tha laat paga with a printad or iHuatratad impraaaion. Tha last racordad frama on aach mierofieha shall contain tha symbol ^-^ (moaning "CON- TINUED"), or tha symbol ▼ (moaning "END"), whichavar applias. Las imagas suhrantas ont ttt raproduitas svsc is plus grand soin, eompts tsnu ds Is condition st do ia nattat* da fasampiaira film*, st sn eonformita avac las conditions du contrst ds filmaga. Laa aaamplairaa originaux dont la eouvarturs sn paplar aat imprimAa sont fllmas sn eommsncsnt par ia pramiar plat at ti tarminant salt psr Is dsmMrs paga qui compona una smprsints dimprasslon ou d'iilustrstion, soit psr Is tscond plat, salon ia cas. Tous Iss sutras sxsmplsirss originauK sont fHmto sn commandant psr Is pramiAra paga qui eomporta una amprainta dimpraasion ou d'lHustrstlon st sn tsrminsnt psr ia damlAra paga qui eomporta una tails smprainta. Un daa symboiss suivants spparaltrs sur Is darniira imaga da chaqua microfichs. tslon Is ess: la symbols — *> signifis "A SUIVRE ". Is symbols y signifis "FIN". Mapa. platas. charts, stc. may ba fllmad at diffarant raduction ratios. Thoss too larga to bo entirely included in ona axposura ara fiimad baginning in tha uppar laft hand comor. loft to right and top to bottom, aa many frames as required. The following diagrams liiuatrata the method: Lea cartes, pisnchss. tableaux, etc., peuvent itrs filmte i des taux da rMuetion diffirsnts. Lorsqus la document est trop grsnd pour itrs reproduit en un soul ciichS, il est filmS i psrtir ds I'sngle supArieur gsuchs, ds gsuchs * droits. st do haut en bas. *■ . prensnt Is nombrs d'imsges ndcsssaira. Los disgrsmmss suivsnts iilustrsnt Is mathode. 1 2 3 1 2 3 4 5 6 ••eioeofy msoiution tut ouit (ANSI and ISO TIST CHAUT No. 2) A ^jg PLIED IIVHGE I ''" Eo« Moin StrMt (716) 288 - 5989 - To, DOMINION OF CANADA DEPAi^TMENT OF AGRICULTURE ENTOMOLOGICAL BRANCH C. OOROON HtWITT, DOMINION CNTOMOLOOItT CANADIAN BARK-BEETLES PART II PRELIMINARY CLASSIFICATION, WITH AN ACCOUNT OF THE HABITS AND MEANS OF CONTROL BY J. M. SWAINE, Assistant Entomologist in Charge of Forest Insect Investigations BULLETIN No. 14 {Technical BvUeHn) Published by direction of the Hon. T. A. Crerar. Minister of Agriculture. OtUwa e/ OTTAWA J. D« LABROQUERIE TACHt PRINTER TO THE KINGS MOST EXCELLENT MAJESTY 1918 ISSUSD SBPT. «, 191S. ■3r:^-,i^^ri"5Ji5!i::; J DtPARTMxirr or Aoucvltvm, Ottawa, September 14, 1917. To the Honourable The Minister of Agriculture, Ottawa, Ont. B.ii^/"'v^^^?i^l^t?°°".*° ""*""'*' '°' y°"' approval. Entomological Bulletm No. 14, Part II, entitled "Canadian Bark-Beetles; Part II- A Pre- hminanr Classification, with an Account of the Habits and Means of Control " which has been written by Mr. J. M. Swaine, Assistant Entomologist in char« of Forest Insect Investigations. As I pointed out in Part I of this series, the bark-beetles constitute the chief insect enemies of our coniferous forests. Forest fires are spectacular, and the results are immediately and strikingly noticeable, but competent authi orities are of the opinion that the annual loss caused by the depredations of these and other forest insects which are widely distributed throughout the country is greater in the aggregate than the loss due to forest fires. The methods to be adopted to control the outbreaks of these serious enemies of our forests depend upon a knowledge of the species of bark-beetles concerned. Different species have different habits, and as control measures are based upon their habits it is necessary for the forester to be able to recognize the various species that are to oe found affecting our timber and shade trees. The object of this bulletm which brings together the results of the work of many years s to place m the hands of foresters, students, and other workers requiring such information a means whereby they will be able to identify readily the species of bark-beetles causing any injuries that may be found in our Canadian forests. n»fi^ " ,^« 8f ««»] Jiabits and of the methods of controlling bark-beetle ouiort .ded, and descriptions are given of a number of new species. r^»J '"' °! "°* ^^^ protection and correct utilisation of our timber JST'' Wh.n Z t "°P?.'*»"''« ^^^ ev«r from a national and imperial stand- Pf;°*- ^,'**° *^ "formation contained in this bulletin is available to practical oresters it will be of inestimable practical value, as it will assist them in Sg the necessary steps to prevent the continued loss of timber now being destroyed ' It ""a""' '^'°"'^' "'"^ *^** "« threatened by the attacks of bLkSes i most insidious enemies of the forest. oeenes. I have the honour to be, sir. Your obedient servant. 3619»-1§ C. GORDON HEWITT, Dominion ErUomologist and ConniUing Zoologist. \W a)XTENT8. Pahr 7 H » B Introduction 1. Thi- HtMtlc- Mtd Their tlabitii. Tin- Liff Sttt([rB OriH"ttl ilubitit AlxTKuit (lubitH The iMnils of th»' Tunnplii The Entrance Hole .. . Th»' Kntranct>-tunnvl>i Jl The KKK-tunni-lii pruiM r H The \>i)tilHtii>n>tunn«'l Secondary Kiiemien 03 Neutral Species ^ The Importance of Bark-beetle Injuries in Ciwuuiiiin i-'ore-tH. . ..!!!!'''!!!!].!! 28 The Normal Annual Lokh 23 Sporadic ( )utbrcakM ^ Epidemic ( )utbreakH «T Conditions Fiivouring Bark-beitle Outbreaks Sk Slash I? (■round Fires |tX Other Factors f| Natural Control Fuotors 5? Parasitjs. " Predators Birds 2a 26 27 Parasitic Vi" ti nL Methods of Cor it tit . ^'"' Interrela between lire ami Bark-lMetles. . . . . -iM HI. >tructural Characi^.a of the bjirk-heetles S, General Characters of the Body ^i The Head ^ The Thorax if? The u-gs :;;:;: :' , ' The Elytra i/. The Abdomen .A Internal Characters 5^ U . Classifisation. A Preliminarj- .VrranRPinent of the Canadian Bark-he.-lies. '.'.['.''.'.'. 35 Introiluctory 5? Paired Species [ 5^ The Superfamily Ipoidea. . ^ " iS The Family Platypodidx iZ The Family IpidiB ^1 The Subfamily Eecopto^ st."-in:e .,n The Subfamily Hylesir.inas o„ Tho Subfamily Micracina; ^i The Subfi'milv fpinjc I^ List of Coniferous Host Trees. . . i|t Glossary }^* References to Literature. ..' .'\n Index to Genera and Speoies and to the PJatis] ..'...' 140 i Ul Canadian Bark-beetles. PART II. A PRELIMINARY CLASSIPICATION. WITH AN ACCOUNT OF THE HABITS. INJURIES AND MEANS OF CONTROL. Bt J. M. SwAiNi INTRODUCTION. Th« buUetin has been written with the object of assiRting students and practical forMten m determining the bark-beetles of Canadian forests The majority of the species occurring in the northern regions of the United States have also been included, since nearly all may eventually be found in Canada. Ibe bark-beetles of this country have thus far received but little attention from moat coUecton and students o' ♦he Coleoptera. There were until recently CO many common species undescriL- and the older descriptions were so incom- plete, that their determmation was frequently given up as a hopeless task. Furthermore, while many of the species may be obtained in quantity, when ♦he collector knows their habits, most of the bark-beetles are taken only in the Dark or wood of their host trees, and then only by those who seek them. Owing probably to these two causes our literature shows a lamentable dearth of biolo- gical papers on North American bark-beetles. While the life-historiee ana habits of the European species have been discussed in scores of papers, the habits D ^* MteT' °"" '***" published, excepting the species of tho genua There are still numbers of our species undescribed. Some have been received or coUected since these keys were finally revised. Others are repre- sented m our collection by one iir two specimens, mid may prov fo he only marked variations, uid there are many other species, undoubted ; hat have not yet been collected. The study of a group of beetles containing so many dt itructiv„ enemies of lorrats «jd shade trees is of particular importance. Careful and detailed studies of the structural characters and habits must be mad^ ho that the injurious species may be readily determined and practira' -emediea ( rtectcd. A single dying pme or spruce may contain many specie.' o< bark-bec^Vs working in the bark and wood. The entomologist must be abie v>> determine all the different species he meets and must have a working knowledge of the habits of all of tnem so that, with the assistance of the evidence before him in the trees them- selves, he may be able to select the species responsible for the primary injury to the timber. It is evident, therefore, that intensive laboratory studies upon the morphology and classification of the beetles are absolutely necrssary, aud that time spent upon even the species of apparently minor economic importance may give decidedly practical results. Mr. A. E. Kellett, Artist Assistant in the Entomological Branch, has drawn the illustrations which bear his signature, under the supervision of the writer, and has prepared many of the photographs. The writer is indebted to many students of the Coleoptera and to several institutions for the privilene of studying their collections. This assistance will be ackno- .edged more fully in later pubhcations deahng with the biology of the species. 7 i^\ f THE BEETLES AND THEIR HABITS. The Life Stages. The Bark-beetles are small, usually cylindric beetles, from one to nine millimetres in length, and brownish or black in colour when mature. They are found in company with their small, whitish, legless grubs, cutting tunnels in the bark or wood of trees. Figures on plates 4 and 5 illustrate types of the tunnels cut by them. In common with other beetles there are four life stages: the egg, the larva or grub, the pupa or resting stage, and the adult beetle. The eggs are usually oval, elongate-oval, subglobular, or rarely somewhat elongate; pearly white or translucent and watery; with a very delicate covering when deposited in niches and packed with boring dust, but with a thicker skin when left loose in the galleries (PI. 3, figs. 1,3). The surf ce modifica- tions appear to be of minor importance. They are, of course, very small, but sometimes of an astorishing size in relation to the size of the mother beetle. The eggs of Crypnalua are almost as large as the beetle's abdomen. The larvce are always legless, whitish in colour, with darker, strongly chitin- ized head and mandibles, and with the thoracic segments distinctly larger than the others, in the true bark beetles (PI. 1, fig. 2). In ambrosia^beetles of the genera Anisandrus and Xyleborus, the larvae move about freely in the tunnels, and they are more elongate and distinctly more mobile than the others. The characters of the larvae will prove of considerable assistance in the classification of the family; and in addition, they are of decided practical value, since not infrequently the larvae alone are obtainable in material sent in for determination. A discussion of the larval characters, however, must be left for a later publication. A distinct prepupal, quiescent stage, lasting a few days, is common m the family. . . The pupce are formed in the ends of the larval mmes, sometimes m pupal cells. They are white at first, becoming yellowish before transformation. They are variably armed with spines and stiff setae, and present characters of decided importance (PI. 1, fig. 3). The adults are yellowish when they emerge from the pupal skin, but rapidly become darker in colour, passing through yellow to reddish and dark brown or nearly black. PLATE 1. IPID BEETLES, All Greatly Enlarged. (Orioinal.) Fig. I, Dendroctonus innnticolneHopk., upper left. Fig. 2, Dendroctonus monlicolae Hopk., larva, upper right. Fig. 3, Dendroctonus borealis Hopk., pupa, right centre. Fig. 4, Pityophthoms nitidua Sw., lower right, Fig. 5, Pityophthoms nitidm Sw,, flotails of the pronotum. left centre, autenna incorrect. Fig. 6, PityophthoTUs nitidus Sw., caudal view of the fleelivity, lower left. 8 PLATE No. 1. ■I « 1 ■ i SHH^ Gbneral Habits. In habits the Ipidm of our fauna form a sharply isolated group. Their tunnels, cut usually in the bark or wood of trees, are characteristic of the family. Our species present two quite distinctive habits, corresponding to which they have been termed True Bark-beetles and Ambrosia-beetles, respectively. The former, with very few exceptions, cut their tunnels entirely or almost entirely in the bark or between the bark and the wood; the latter, on the other hand, penetrate the wood and the young develop in the tunnels well below the wood surface, nourished entirely by a peculiar fungus called Ambrosia, which grows invariably upon the tunnel walls and stains them dark brown or black. With True Bark-beetles the typical habit is as follows: An entrance tunnel is cut obliquely upward through the bark to the wood surface. From the base or inner end of the entrance tunnel one or two or more egg-tunnels are cut, vertically, transversely, or in a radiate fashion, between the bark and the wood along the wood surface. With many species a small, flat cavity, the nuptial chamber, is excavated at the base of the entrance hole, and from it the egg- tunnels originate. The eggs are laid along the sides of the egg-tunnels, singly in cup-shaped egg-niches, a few together in larger egg-pockets, or many in layers and egg-grooves. The egg-tunnels and entrance hole are uniform in size, slightly larger than the diameter of the beetle, and perfectly cylinclrie. The larvae excavate slender mines through the inner bark or between the bark and sapwood, away from the egg-tunnels. The larval mines are filled \vith excrement and increase gradually in diameter as the larvae grow. With some species the mines are kept regularly spaced, rarely intercrossing unless crowded, and present a regular and pleasing pattern; such are those of Chramesus icorim Lee, (PI. 23, fig. 5) in hickory twigs, and Leperisinus aculeatus Say in ash (PI. 5, fig. 8). With other species the larval mines are quite irregular and when numerous reduce the inner bark entirely to powder. The ends of the minis are widened to form a more or less distinct pupal cell, which may lie between the bark and the wood, may be continued into the middle layers of bark, or may be sunken below the wood surface, accoriling to the species hal)it. The adult beetles finally bore round holes through the bark and escape. The result of this excavation by adults and larvae is a set of egg-tunnels and larval-mines, characteristic of the family, frequently of the genus, and commonly of the individual species. The tunnels of the ambrosia-beetles are discussed briefly on the following pages. They will not be confused with those cut by any other Ix-etles of our fauna. A distinctive character is the blackening of the tunnel walls by the ambrosia fungus. The larval tunnels of Hyleccetus are somewhat similar and are also lined with a fungus, but they are not similarly discoloured. The tunnels of Slenocelis might be mistaken for those of ambrosia-beetles, but there is no staining from fungi, and the larvae tunnel freely in the wood. Aberrant Habits. The tunnels of a few of our species of Pilyophthorus, notably ramiperda and puberulus, cut their tunnels through the pith of pine twigs (PI. 4, fig. 5). Several species of Conophthorus excavate egg-tunnels through the pith of pine (•ones (PI. 8, fig. 5). Hylastinus obscurus Marsh, makes normal egg-tunnels m clover roots. A species of Pilyophthorus cuts the egg-tunnels immediately below the wood surface of dry maple twigs, and both adults and larvae feed upon the black wood fungi which abound in sapwood of the twigs they select. Exotic species are found in various nuts, date pits, nutmegs, jalap root, and dry twigs. Species of Xylocleptes breed in plants of the gourd family. Several ambrosia-beetles are recorded cutting their tunnels in the staves of wine casks 1 iW 10 and in similar places. Aberrant habits are much more common in tropical countries than with us. The vast majority of our species breed normally in the bark or wood of trees. Details or the Tcnnilb. A study of the egg-tunnels and larval-mines reveals many important and interesting characters. A distinctive form of the galleries obtains with many species, so that an examination of the tunnels in the bark or wood may determine exactly the species to which they belong. It is thus possible to determine which species have been working in a tree, even years after the beetles have left, and if the galleries were engraved upon the wood, even after the bark has disappeared. The work of Chramesiis icorice Lee. in hickory branches (PI. 23, fig. 5), of Leperisinua aculeatus Say in ash (PL 20, fig. 2), of Eccopto- gaater picaa Sw. in spruce and fir (PI. 20, fig. 3), of E. rugulotus Ratz. in fruit trees and wild cherry (PI. 5, fig. 7), of Phloeosinus canadensis Sw. in eastern cedar (PI. 5, fig. 5), of DryocoeUs confusus Sw. in mountain balsam (PI. 19, fig. 1), and many others, may be specificially determined, even though, as rarely happens, no old dead beetles are to be found in the bark. THE ENTRANCE-HOLE. The entrance-hole with most species is usually free from chips or frass except while this material is being extruded; but with certain other species there are peculiar characters connected with it. The boring-dust and excrement of Xyloterinus politus Say projects from the entrance-hole while excavation is active, often for several centimetres, as a cylindric rod of the diameter of the entrance-hole. During a period of fine weather these are often visible in great numbers on the trunks and limbs of dying, infested maples and beeches. The entrance-holes of T. retusua Lee, on the other hand, are readily distinguished by quite different characters. The opening is covered by a cup-like layer, an aggregation of excrement. Through a small hole in the centre of this cup, which is convex outwards, a slender thread of excrement projects, pushed out by additions from within, until finally broken by rain or by the action of gravity. The air circulation in tunnels so blocked at the entrance must be extremely slow. The borings of Eccoptogaster rugulosus Ratz. and Phthorophloens liminaris Harris in green bark of peach trees and wild cherry trees result in a copious ex- udation of sap, and the hardening of the sap produces conspicuous gummy masses about the entrance-hMies. The flow of resin from the tunnels of certain species of Dendroctonus, Ips, and others, in green bark of pines and spruces, results in a " pitch-tube " or " resin-tube " about the entrance-hole. The beetles are able to live in spite of the exuding resin, and by their movements backward and forward in the ejection of the boring-dust, form the surrounding tower oi gum upon the bark. The presence of this " resin-tube " about the entrance-hole proves that the tunnel was started in fresh, sappy bark. With many species of Ipid beetles the male spends part of his time backed into the entrance tunnel near the opening, which he neatly fits, and through which his declivity is often visible. In species whose males are wingless, and therefore have no part in the construction of new timnels, the female adopts this function of guarding the entrance, in addition to her other regular duties. With a few species, like Chramestis icorice Lee, one or other of the parent adults dies in the entrance-hole, and thus prevents the intrusion of later enemies. This closing of the entrance-hole for a considerable part of the time guards in a measure from predacious and parasitic enemies, and checks evapor- ation from the tunnel walls. u THE ENTRANCE-TUNNELS. The entrance-tunnels of the ambrosia-beetles pass directly through the bark and more or less deeply into the wood. There they give off side tunnels, along which the greater number of the egg-niches are cut, or in which the eggs are deposited free, according to the habit of the species. The entrance-tunnels of the True Bark-beetles either pass directly through the bark, or in most cases traverse it more or less obliquely, to open into the nuptial-chamber or directly into the egg-tunnel within. The length of the entrance-tunnel is never great, and varies with the thickness of the bark in which the beetles are working. In the thick bark of large pine trunks, thinner places, the bark fissures, are frequently chosen for the location of the entrance- holes. Some species of ambrosia-beetles prefer to start their tunnels on freshly cut or broken surfaces. The entrance-tunnels are always perfectly cylindric, a result of the shape of the beetles and their constant revolution during the excavation. Certain species usually cut their entrance-tunnels obliquely upward, so that it is possible to tell whether the tunnels have been cut before or after the trunk has fallen. THE EOO-TUNNELS PROPEft. The egg-tunnels of the True Bark-beetles are usually cut between the wood surface and the bark, engraving both. Certain species cut the egg-tunnel entirely within the bark. Orthotomicus calatua Eichh. has this habit when workmg in the thick bark of mature white pine, although on branches and trunks of smaller trees its egg-tunnels engrave the wood surface more or less distinctly. The egg-tunnels of many species are almost entirely within the bark, only scoring the wood slightly; such are those of Phlaosinua canadensis Sw. m cedar. On the other hand the tunnels of Chramems icorice Lee, Leperi- sinus acukatus Say, Pityopthorus canadensis Sw., and many others, score the wood very deeply, and thop» of a few species, such as Pityopthorus ramiperda Sw. and Lymantor decipiens Lee, are almost entirely or quite below and parallel with the wood surface. Certain species of Hypothenemus, Stephanoderes, Micrwas, and Pityophthorus cut their primary tunnels within the pith of twigs, and have, on this account, been termed " twig beetles." Some species of Pityophthorus cut their egg-tunnels usually upon the wood surface of twigs, while their larvae frequently bore to the centre and pupate in the pith. The egg-tunnels of the ambrosia beetles branch from the entrance tunnels m various ways, to be described in more detail under the several species in later papers. The species of Gnathotrichus, Pteroeyclon, Trypodendron, and Corthylus cut their egg-tunnels at a greater or less depth below the wood surface, according *?*"e species and particular conditions of the wood, and vary somewhat in indi- vidual habits. All the species in these genera cut egg-niches above and below along the walls of the egg-tunnels, and later even along the entrance fmnels. Ihese niches are similar to those cut by most True Bark-beetles, and the eggs are usually packed in with boring-dust and excrement. The niches are widened and lengthened by the larvae to form short side tunnels or " larval cradles," "/"Krof* '''*^* *°^'®^ *° ***® egg-tunnel, and only slightly longer than the larva Itself (Fl 3, fig. 8); compound. The egg-tunnels of Anisandrus and Xylehorus are usually merely side tunnels arising from the sides or the distal end of the entrance tunnel. The eggs, in these two genera, are deposited free in the tunnes and the larvae live therein without cutting cradles; simple. The tunnels of Xylehorus saxesceni Ratz. are peculiar in that the larvae excavate cavities in congress (PI. 2, fig. 13). • I I* If .interesting to note that certain species of the genus Platypus (formerly included in the Family Ipida), which occur in the southern and western portions ot tb- "ontment, lay their eggs, according to Hubbard and others, free in the 17 It tunnels, their larvte cutting cradles similar to those excavated by larv» of the Ambrosia beetles already mentioned, and are thus in a manner intermediate in habit between Xylebonu and Trypodendron. The only Canadian species of the genus lays its eggs free in the ends of the tunnels, and its larvo apparently do not cut cradles.* The tunnels and cradles of Ambrosia beetles are lined with a fungus used for food and usually characteristic of the beetle species, or at least of allied groups of species. As this subject is to be discussed in greater detail elsewhere, it is sufficient here to observe that all Ambrosia beetle tunnels are characterized by the presence of one species of these fungi during the egg-laying season, ami later contain, in addition, numerous saprophytic as well as parasitic forns. The tunnel walls are invariably stained brown or black by the action of the Ambrosia fungus upon the wood. THE VENTILATION TUNNELS. These are short tunnels cut at intervals along the roof of elongate egg- tunnels ip certain species of Dendrodonua and Ips, directed outward towards or to the outer surface of the bark (PI. 2, fig. 3). The length of these venti- lation tunnels depends upon the thickness of the bark overlying the egg-tunnel, and may vary from a millimetre, or less, to more than an inch. They sei-ve as turning-niches and storage-places for boring-dust, and in some measure may increase the air circulation within the egg-tunnels. Many such tunnels that I have examined ended bluntly in the outer layers of bark, and could only serve as turning-niches, storage-tunnels, and to increase the body of air available for the beetles. With certain species, as Dendroctonus simplex Lee, the long egg- tunnel is often blocked in places with boring-dust, so that these ventilation- tunnels are perhaps useful, in such cases, for air circulation, but are certainly necessary as cuming niches for the female. •Recording to Chamberlain, Or. Ag. Exp. Sta. Bui. 147, 1918, the larvte of this specicB also cut cradles shortly before pupating. PLATE 2. TYPES OF EGG TUNNELS. Fig. 1, Forked, longitudinal. Fig. 2, Simple, longitudin.al. Fig. 3, Radiate, typical. Fig. 4, Cave-tunnel. Fig. 5, Radiate, modifiel; Ips cnn'inniis Mannh. — ^.h., entrance hole; e.p., egg-pocket; e.t., egg tunnel; l.g., larval gallery; n.c, nupti.al chamber. Fig. 6, Irregular, short. Fig. 7, Radiate, transverse. Fig. 8, Forked, transverse. Fig. 9, Radiate, longitudinal. Fig. 10, Forked transverse, with larval mines, Phlhorophloeus. Fig. 11, Radiate, egg-tunnels commenced, Ips pint Say, from below. Fig. 12, Ambrosia tunnels, simple, horizontal. Fig. 13, Ambrosia tunnels, eompoimd, goci.^1 gallery, X. saxesreni Rata. Fig. 14, Ambrosia tunnels, compound, with cradles, Pterocyclon mali Fitch. Fig. 15, Pith tunnels, Micracis. Fig. 16, Ambrosia tunnels, compound, with cradles, Gnathotrichus. Figs. 17, 18, Ambi^jsia tunnels, simple, vertically branched; Anisandrus. PLATE 2. I' > i H BOO-NICRU. The peat majority of North Americui bark-beetles depotit their tfus ■ingly in Hmall nichei, termed egg-niehe», cut along the sides of the ecg-tunnMS. These are shown distinctly in the illustrations of the tunnels of Leperiainut aeuUatua Say, Pityogtnu hopkiiui Sw., Pityapthonu earinieepa Lee., and many others given in this paper. Usually the niche is cup-shaped, with a circular opening, and is somewhat deeper than the thickness of the egn. The niche is cut with the mandibles, and usually at the extreme end of the egg-tunnel as thus far cut. The siie of the niche m relation to the sise of the egg varies with the species. The tunnel face of the wall of egg-packing is usually slightly convex, so that the cylindrical character of the tunnel it* but little altered; but certain species cut relatively small niches, with the result that the eggs and their covering of dust project decidedly into the tunnel. EGO-POCKVrS. These are large niches cut along the sides of the egg-tunnels by species of Dendroetontu, Iva eoncinnus Mannh., Ortkotomieua eaelatiu Eichh., and others, in which several eggs are deposited and packed with boring-diut. 0. eaelahu deposits from two to eight eggs in a mass at the bottom of each pocket. Dmdrodontu timplex Lee, places three or four eggs side by side in the bottom of an elongate shallow pocket or very short groove. The details vary consider- ably with the species and with the environment, and apparently to some extent with the individual. D. aimplex often deposits a few eggs in the boring-dust which fills portions of the tunnels. BOQ-OROOVKS. Dendroetontu valena Lee, Hylurgopa pinifex Fitch, DryoecOet americantu Hopk., and others, deposit their eggs in layers or rows along one or both sides of the egg-tunnels. The tunnel is Mridened or grooved for the reception of the layer or layers of eggs and their invariable protective covering of boring-dust. Hylurgopa pinifex Fitch, often deposits three layers of eggs in one groove. The continuous wall of egg-packing covering the egg layers is in line with the tunnel wall so that the cavity of the tunnel is cylindrical, and but little larger than the circumference of the beetles. Here again, the details vary greatly with the species and often markedly in the same genus. Dryocatea americanita Hopk., frequently deposits a few eggs in the roof of the tunnel. TURNING-NICHES. These are cut by Dendrodonua simplex Lee, and others, at intervals along the sides of the egg-tunnels; they are rather wide and deep excavations, and are used by the beetles for reversing their position, exactly as a street car or railway train uses a " Y " in the track. I have only rarely found a few eggs deposited in them. Certain species cut a short tunnel or a niche at the base of the entrance-tunnel at an angle with the egg-tunnel; these serve in the same mannei for turning. The constructors of forked tunnels use the two branches of the egg-tunnel and the entrance-tunnel for the same purpose. The ventilation- tunnels, previously referred to, and the nuptial chamber are also used for this purpose as well as for copulation. THE NUPTIAL CHAMBER. Many polygamous and a smaller number of monogamous species have a distinct chamber in the inner bark at the base of the entrance hole, called the 15 nuptial clumber, from which the egg-tunnels originate. The Btar-«haped tunnel* of Ipt, PHyoQtnf. PityovhthoruM in part, Polyaraphut, and others, have a distinctly flattenea nuptial chamber, usually relatively large, either entirely in the inner bark or enjpaving the wood surface. In the normal star-shaped type the egg-tunnels radiate from all sides of the chamber; in the modified type cut by Ipt eattianphua Germ., /p« perturbatiu Eiehh., and others, the two or three tunnels artae from the chamber at the opposite upper and lower sides. The ufiMptnoaiM group of Eceoptogaater cut a vertical tunnel above and below from opposite sides of a rather large nuptial chamber (PI. 20, fig. 3). Two other types of tunnels are cut by the species of the genus Eceopto^atter, as at present constituted, one simple and vertical E ru^onu, the other forked and transver«o (Pi. 4, fig. 1). The species of Phlaotintu cut a single vertical egg-tunnel, usually vith a large nuptial chamber at the base of the entrance tunnel (PI. 5, fig. 6). Many modifications of the chamber appear in the family, varjring m>m the indefinite cave-tunnel with one or two irregular egg- tunnels, cut by some PityopMhortu, to the perfectly Etar-shaped tunnels of Pityogerut and some species of PityoplUhorus and Ipt. The beetles utilise the chamber for several purposes. It serves as a temporary storage room for boring dust thrust into it by the females working in the egg-tunnels; it is also used by the beetles for turning or reversing their position, particularly by species which cut no ventilation tunnels; and it is used regularly for copulation. With polygamous species the male spends nearly all his time in the nuptial chamber and in the entrance tunnel. The nuptial chamber is a special modification, aiid has apparently arisen independently in several groups of genera. The star-shrped tunnels of Polynraphru, with a distinct chamber, are c'osely similar to those of some I pa and Pityonenea; but the beetles are structurally so widely separated that no community of origin could account for their similarity in habit. The chamber is well developed in Eceoptogaater and Phlceoaintu, and these genera are not only widely separated morphologically from each other but also from the two groups just mentioned. In the iperuu Pityophthorua we find evidence that the star-shaped type may have arisen in this instance from the more primitive cave-like tjrpe still cut by some species of the genus; and the habit may be explained in allied genera by community of origin. In some species of Dryocatea we find what appears to be a secondary degeneration from the star-shapeid type to irregular tunnels without definite plan. The chamber has apparently arisen independently in Eceopto- gaater, Phlceoaintu, and others, as a simple enlargement of either the egg-tunnel or the entrance-tunnel, at or near the junction of the two. m FOOD-TUNNELB. The feeding habits of the adults vary greatly wiih the species. In the process of cutting the egg-tunnels much of the excavated wood is swallowed, and many species apparently obtain sufficient nourishmeni in this way. Other species excavate special food-tunnels either before or after cutting the egg- tunnels. The young adults may feed extensively before emerging from the bark, cutting winding food-tunnels, " brood burrows," between the bark and the wood, as with species of Ipa, Pityogenea, and others; or they may leave the parent tree directly from the pupal cell, and cut food tunnels in the bark of other trees, as with species of Ipa, Phlceoaintia, Eceoptogaater, and others. The parent adults may extend the egg-tunnels as winding food-tunnels, " terminal burrows," or cut short food-tunnels elsewhere before beginning their second set of egg- tunnels. This intermediate period of rest and feeding is needed, apparently, in order to mature the second lot of eggs. i-i- Thb Ttpxs or Eoo-TVNNSLa. The egc-tunneU present nianjr variatioiu in form, even in the same genu and interesting similarities in habit occur between species belon^png to widel separated genera. Several arrangements for classifying the ipid egg-tunne have been suggested. The variations in the tunnels are so numerous that detailed classification must be cumbersome if at all complete, and the bri< arrangement in the following table will perhaps be more useful for the purpoi of this bulletin : — Irrcoulab Elongate Tunnels — Dtndrodonu$, Hylurgopt, HyUutea, et Irreqular Short Tunnels. — DryocaUt (in part), etc. Simple LoNaiTtroiNAL Tunnels. — Phlaotinus, EceoptogaiUr (in part Chrameaut, etc. Siu^^'^E Transverse Tunnels. — Cryphalua, Eeeoptogatter (in part) ; rar Fc *ED Tunnels. — Longitudinal or transverse; Leptriainua, Paeud hyleainua, Eccoptogaater (in part), Phthorophlaua, etc. Radiate Tunnels. — Ipa, Pityonenea, Pilyophlhorua (in part), Pclygraphu etc. Cave Tunnels. — Cryphalua (in part), Pityophthonu (in part). Pith Tunnels. — Micracia, Stephanoderea, Pityophthonu (in part). Ambrosia Tunnels. — Simple; Aniaandrua, Xyleborua. Compoun< Gnathotrichua, Pteroq/clon, Trypodmdron, Xyloterintia. Page 11. Fig. FiB. Fig. Fig. £«• Fig. Fig. Fig. Fig. Fig. Fig. PLATE 3. AMBROSIA-BEETLE TUNNELS. 1, AnUamlrut populi Sw.: eggs, Urvie and pupae; 1| times natural sise.* 2, Trypodendron rettuua Lee.; tunnel in poplar; about natural lize, showing a pupa in i cradle. 3, Animndrm obeaiu Leo.; tunnel in beech, shuwing eggs lying in the inner end.** 4, Trypodeitdron retutui Lee.; larvte; about natural size.* 5, Ani»andru» pyri Peck; tunnel* in apple; about i natural siae.* 0, Trypodmdron retutut Lee.; tunnels in poplar; about i natural siie. 7, Trypodendro' betulce Sw.; tunnela in burcn; i natural sise. 8, Onatholrichv. materiariut Fitch; tunnela in pine, showing larvie, pupa, and adult; natui sire." 9, Anisandrus pyri Peck; exit holes in apple limb; about i natural siie. 10, Aniiii.' dnu populi Sw.; tunnels in poplar. 11, Trypodendron retu»iu Lee.; tunnels in poplar, showing small larvB.* 12, Eggs, lar\'K, and pupse of Aniaandru» populi Sw.; slightly enlarged. PLATE 4. BARK-BEETLE TUNNELS (Original.) Fig. 1, Eccoplogaster subscaber Lee.,; tunnels in lowland fir; wood surface; J nature size. Fig. 2, PuudopUyophthorus tuinulisaimus Zimm.; tunnels in hazel; wood surface; natural size. Fig. 3, Dendroctonua monlicola Ilopk.; pitch-tubes in western white pine trunk; much reducec Fig. 4, OrMotomu-w* fffiaJiw Uichh.; tunnels in white pine bark; about natural size. Fig. 5, Fityophthoma nitidus Sw.; tunnels in pine twig, on the wood surface and in the pith } natural size. Fig. 6, StuHv-tunnela. covered with sheet celluloid. Fig. 7, P opWofM* pice* Sw.: tunnels in white spruce branch; J natural size. Fig. 8, t -nicug caelatus Eiehh.; tunnels in white pine, inner sitfface of bark, showing inn be- uirely reduced to powder. Fig. 9, Dendroctonus bore™« *o t'rae ■«nall local bark-beetle outbreaks occur usually in the neighbourhood of slash from cuttings, wind falls, or fire-killed timber. The beetles concerned are frequently common secondary species, which, having had suitable opportunities for rapid breeding, find themselves numerous enough to attack the nearby green timber successfully; these have already been referred to under " Secondary Enemies," page 23. These minor outbreaks are easily controlled, and may die away without causing extensive injury; on the other hand, if they have been originated by some of the more destructive species, they may become epidemic, and devastate the whole countryside. Small outbreaks by a destructive primary enemy should not be disregarded. EPIDEMIC OUTBREAKS. . Barlf-beetle outbreaks may be considered epidemic when they spread rapidly over a wide area, involving the death of many hundreds or thousands of trees. Under these conditions the beetles occur in immense numbers, and attack the green timber with the greatest readiness. Often the largest and finest trees are selected. The one or more primarv enemies really responsible for the spread of the injury are accompanied invariably by numbers of second&ry species. Many examples of these extensive injuries have occurred in Canada and the United States during the last century. The Destructive Eastern Spruce Bark-beetle, Dendroctonua piceaperda Hopk., has killed many millions of feet of spruce timber in Maine and New Brunswick during a series of destructive outbreaks, the last of which occurred between the years 1897 and 1900. The best known Canadian examples are those still spreading in the yellow pine in southern British Columbia, caused by the Western Pine Bark-beetle and the Western White Pine Bark-beetle, and those in the western white pine and PLATE 6. BARK-BEETLE BREEDING GROUNDS (Original). Fig. 1, A slashing on Vancou'. r Island; an ideal breeding ground for beetles. Fig. 2, Beetle-killed yellow piiie, Indian Meadows, B.C. Fig. 3, Beetle-killed western white pine, B X Mountain, B.C.; the dead trees were killed by the w estem White Pine Beetle many years ago. Fig. 4, Beetle-killed lodgepole pine, Trepanier Creek, B.C. HI.ATK No. «. Wri in i I \ i ss lodgspok pbe e»ua«d by the WMtcro White Pine Bwlc-beetie. In pwta of the imetted country the trouUe cd epidemic. CoNoiTiONB Favourino Bark-bebixc Outbrkakb. In addition *o the weather, latitude and altitude, there are vai-iou« local conditiona whici ^vour the rapid development of the beetles, and, therefore, are directly concerned in the origin of sporadic and epidemic outbreaks. 8LA8H. The refuse from cutting operations, culls, branches, tops, and stump* affords an ideal breeding-ground for practically all our injurious bark-beetles as well as for many other injurious species. J.,ogging operations, settlers' clearings, and even cuttings for firewood and for trail-making, provide slash that may prove a positive menace to the surrounding healthy timber. In order to control our destructive bark-^tles it is only necessary to reduce the numbers so that the normal amount of dying bark to be found in the woods will suffice for breeding purposes. Apparently all our bark-beetles have, normally, a preference for dving bark; and it is only when their numbers are very great that green timber is attacked in quantity. It therefore follows that so long as extensive cutting in a district continues, the slash and stumps serve as a breeding-place, and to a considerable extent, or for a time often entirely, protect the healthy trees from most species of beetles. Broods of our most injurious species which have bred in an epidemic outbreak in green trees have apparently a decided tendency towards green timber. Unless the amount of slash increases from year to year, certain species are bound to develop to such numbers that additional breeding-places are requ:red, and then, or, with certain species, apparently before that stage is reached, they attack the sur- rounding green timber. When cutting ceases suddenly there is always danger that an outbreak may develop in the neighbourhood. It is therefore evident that while slash may serve for a longer or shorter time as a partial protection to the standing timber, it is likely to become a nuisance, since it offers an abundant food supply for the beetles in which they may breed to immense numbers. The slash can be made to serve as an eTective trap. Many injurious spt^cies will pass the winter chiefly as young adults or larvK in the bark. If tijc slash of the previous summer's cutting is burned during winter and early spring, a sufficient number of the beetles will usually be killed to hold the injurious species in check. When there is but one brood each season, as with the Mountain Pine Bark-beetle, winter burning of slash of the previous winter's cut will be effective. When species with two broods are involved summer slash burning ra early August, of the previous winter's cut, would assist in their control. The most important consideration, however, is the destruction of the slash by fire before the beetles can breed in it and emerge to infest nearby timber. Properly conducted s'atih burning will be exceedingly effective in averting injuries by both forest ijsect* and fungi. GROUND FIRES. m m Light bums also provide an abundant supply of dying bark for breeding purposes. The injured and slightly burned trees are in some cases as dangerouf 26 -i a: beetle breeding grounds as the slash, and this should be considered when the bums are being logged. If the fire has occurred in the first half of the season and has charred only the bark near the ground, the timber on a burn must be cut during the first winter following the fire, or not later than the second winter, if anything is to be saved from the grubs of the large wood-borers.* Since the logs will contain these living grubs, evep though cut the first winter after the fire, they must be got into water or sawed before spring opens; and when the latter is done the lumber should be dried as rapidly as possible. All green slash and small dying trees on the bum should be piled and bumed to prevent the breeding of bark-beetles and other insects. Trees which have been thoroughly charred from base to top may be disregarded in so far as beetle control is con- cerned. Burns which were made late in the season are, of course, frequently immune from beetle injury, although this is true to a smaller degree in British Columbia than in Eastern Canada. i.l '\i OTHER FACTORS. Wind-falls, snow-breaks, and flood injuries provide more or less dying timber for beetle breeding grounds each season, particularly in the mountain sections. Whenever any extensive injury of this kind occurs in govemment parks or reserves, or on valuable private holdings, it is desirable to have the dying timber utilized or destroyed before it can give forth its crop of destructive beetles. Natural Control Factors. The influence of weather conditions upon the broods has already been discussed. The other natural agencies operating to check the development of the beetles in our forests are, parasites of various kinds, predacious insects, birds and fungi. PARASITES. Small hymenopterous parasites deposit their eggs on the larvae or near them in their tunnels, and the young parasites kill the beetle larvae by feeding upon their body juices (PI. 19, fig. 2). The larger of these parasitic species deposit their eggs through the thin bark overlying the larval mines in the tops and branches; the minute species enter the egg-tunnels and lay their eggs often m the egg-niches. They affect different species of bark-beetles in varying degrees. The most destructive bark-beetles, breeding in heavy, thick-barked timber, are but little affected by them. On the other hand, some species, such, for instance, as Leperisinus aculeatus Say, are frequently very heavily parasitized, and the minute round holes through which the adult parasites eventually emerge from the bark are often thickly interspersed, with the exit-holes of the beetles. A few of our species are sometimes heavily parasitized by mites which breed in the mines and destroy the larvae about the time of pupation. PREDATORS. Predacious beetles and their larvae are frequently abundant about and within the egg-tunnels and mines, and feed upon the bark-beetle adults, their eggs, and the larvae. The influence of parasites and predacious insects appears, on the whole, to be of minor importance in controlling bark-beetles in our forests; although it is possible that some of our secondary species, normally rather heavily parasitized, might otherwise be of primary importance. ♦Except the largest timber of the Pacific Coaat. 27 BIRDS. Insectivorous birds, particularly the woodpeckers, are decidedly beneficial in destroying the broods of bark-beetles whenever their numbers are sufficiently great. Beetle-infested trees are often found with the bark largely riddled by woodpeckers, and the broods almost entirely destroyed. In the beetle-infested yellow-pine area of southern British Columbia the woodpecker work is some- times strikingly evident, and the beetle trees may often be detected in this way (PI. 7, fig. 4). There is evidenco .'uat the birds have at times a decided effect in reducing the numbers of tb hccllt =< over «i limited area; but while their influ- ence on the whole is decided y b°nefici:il, tiii\^ are probably never sufficiently numerous in our woods to cor • rol raore th.\n ery small sporadic outbreaks. f^ PARASITIC r JNGI. The effect of parasitic fungi in destroying broods of bark-beetles has been studied in several instances. This factor appears to be of minor importance in our forests. Methods of Control. Sporadic outbreaks by bark-beetles may usually be controlled without great difficulty; and even epidemic outbreaks, in which many hundreds of trees are dying, may be brought under control, often with very little actual loss. The peculiar habits of the beetles render them vulnerable to attack by the only methods the lumberman could feasibly employ. Our most destructive species iiave one brood, or one brood and a partial second one, each season; they pass the winter as adult beetles and larvse in the bark of the dying trees, entered by the parent adults in the early part of the same season. When in green timber the broods always pass the winter in the trees attacked by their parent beetles earlier in the same season, then usually with yellowing foliage and often with resin-tubes and woodpecker work showing on the bark of the trunk. The beetles never return to the old " red-tops," as the affected trees are called, nor remain in the trees longer than one year. If then, by modified logging operations, these green " beetle trees " can be removed during winter, kept separate, and so treated that the broods in the bark will be killed before their breeding season opens, it is possible to stop the outbreak in one season. If all the green beetle-trees could be treated and all the slash and broken trees burned it would be possible, at least in theory, to exterminate the injurious species from a limit in one v/inter's work. Practically, this would not be possible in dealing with an outbreak of any extent; but it is fortunately unnecessary. If over three-fourths of the broods in the infested trees can be killed before they emerge in the early season, the outbreak can be checked; and by similar work upon the relatively few trees attacked the succeeding season, it can be brought under nearly complete control, provided the entire infested section is treated, so that there will not be extensive reinfestation each year. The largest and most heavily infested trees and the most heavily infested sections should receive special attention. When only a portion of the infestation can be treated each season, it is usually considered advisable to direct the work towards reducing as rapidly as possible the chief centres of infestation in the whole infested section. What portion of the second year's work should be employed in new territory, and how much towards cleaning up more completely on the ground covered iluring the previous winter, must be decided by the conditions of the locality. The details of the control methods will depend upon the species of beetles involved, and partly also upon local conditions, and should be undertaken with the direction of a competent forest entomologist. 28 • *i.^u®°i ** }^^0"?^? necessary to undertake direct control measures, the broods m the bark of the infested trees can be destroyed by whichever of the following methods are best suited to local conditions: — Floatir^the Logs— Where water is available, the simplest method is to cut the mfested logs durmg wmter and float them as soon as cut or as early in the spnng as possible; this will kill the greater part of the broods in the bark. «* ui "^l"^*? J i^'" ""'^ Burning the Slabs— Where it can be done pro- htably, the infested logs may be sawn during winter, and the slabs, which will coi.*ain the brood, burned before the spring opens. Barking the Trees— It is always possible to fell and bark the infested trees during winter, and when necessary, to burn the infested bark before spring opens. Ihe presence of the greater number of the grubs in the middle layers of bark renders burning the bark necessary in the control of outbreaks involving the W estern Pine Bark-beetle. Control operations should be completed usually during the period between the first of November and the following June, but the work should be finished as early in spring as possible. When it is not possible to utilize the timber profitably, and control measures are necessary to protect valuable holdings against ravages of the beetles, the infested timber should be treated by the cheapest effective method so as to d-s- troy the contamed broods. The infested trees maybe cut and burned or thoroughly charred before spring opens, frequently at less expense than by re- moving and burning the bark. It will often be best to combine two ot more of the available methods in order to complete the control work during larte fall, winter and early spring. This control work has reference solely to the freshly infested trees, with fr®?' yf"°*'S"' ,or moderately reddened foliage, having the bark filled with the beetles and their grubs, and not to the old " red-tops " which have been dead for one and a half years or longer, and from which the beetles have emerged. Trap-trees may be utilize 1 in the control of some species. The importance of slash burning in bark-beetle control and the possibility of utilizing it as a trap has already been mentioned. vl The Intehbelations between Fi'be and Babk-beetles. It has been shown that ground fires which injure and kill such large numbers of trees may provide material for the rapid development of bark-beetles. This IS particular]^ true if the bums succeed each other year after year in neighbouring localities. This relation between fires and beetle development has probably always obtained, since fires have occurred in our forests for ages through the action of lightning and the agency of man. When fires run through infested slashings, immense numbers of beetles may be destroyed and tV fire may be very beneficial from that standpoint. When light fires run throi beetle-infested timber the greater part of the broods are not affected by the ' t, since only the bases of the trees are burned. If the hre is very hot so thai the trees are burned far up the trunk, many of the PLATE 7. BARK-BEETLE BREEDING GROUNDS (Oriowal). Fjg. 1, Beetle-killed timber, a clump of red-top yeUow pine near Princeton, B.C. *ig. A 1 unnete of Dendrxtonus horealit, at base of white spruce in Jasper Park, Alta. *!8- ^, / ""?*'H °^ Trypodendron bivillatum in white spruce, Jasper Park. i"ig. 4, Work of woodpeckers on a beetle infested yellow pine, Coldwater Creek VaUey B C PI.ATK \. Si: %i i H iTB I- 'I ■ A « iiJ Bma ;"«m JwiiB Jiy»KWWMi 29 broods may be killed; but the uncertain benefit to be obtained by this burning is usually more than counterbalanced by the certain injury to healthy timber and reprodu'tion. The control of bark-beetle outbreaks in green standing timber by fire should be undertaken only nrith the greatest caution and under expert advice. In our opinion this method of controlwould usually do infinitely more harm than good. After the beetles have killed a large part of the timber, fires are able to obtain terrific headway in the masses of dead trees, and therefore to cause an unusual amount of damage. There are at present large areas in southern British Columbia where for miles all or nearly all the pines have been killed by bark-beetles. The trees have been dead from one to ten or twelve years. When fires occur in such material as this, often on a thin and rocky soil, the heat may bum through to the rock and reduce the section to a timberless w^te for gener- ations. It is not at all improbable that the large areas of rock and range land in southern British Columbia have been produced in past ages through this joint action of beetles and fire. Whatever has happened in the past, it is prac- tically certain that fires will eventually ruin the extensive areas now existing in that region upon which the pine has already been largely or entirely killed, as well as upon that in which the beetles are still actively operating. Fia 5. — ^Ips inteqeb Eichh., autenna. Original. M Ill ill: I STRUCTURAL CHARACTERS. The structures of the ipid beetles are discussed in this paper only very briefly for the purpose of illustrating the keys for determination. The termin- ology already employed in literature is made use of here so far as possible. ■ i !;j.|. ■ , 1 ' :, , !', :;M ' 1 ■ ■ : ■ \'t ^ i i J General Charactebs of the Body. The size varies in species of our fauna from 1 mm. in Crypturgtu and Pityophthorus to 9 mm. in Dendrodonus. The shape is cylindric, varying from very stout, as in males of Aniaandrus, to moderately elongate, Gnathotrichiu, or elongate-oval in outline from above, as in Leperiainus. The colour is usually dark reddish brown or black when mature; all species are yellowish when first transformed, and turn darker as the integument becomes more strongly chitinised. A few genera, as Leperiainua and Pseudohykoinua, have patches of scales of varying shades of brown and grey. Species of Trypo- dendron have the pronotum and elytra varied in black and shades of yellowish- brown. The vestiture varies greatly and presents interesting characters. It varies from long slender hairs to very minute, fine, almost invisible pubescence, to very short bristles or to scale-like hairs, and finally to stout, flattened, plain or ribbed scales. The hairs may be simple or show many plumose and palmate or cuffed variations. Very stout spatulate sets as well as spines are developed on the tibia?. In the ambrosia beetles of all genera, including Platypus, very long, slender sense-hairs are developed in patches on the labial palps. These hairs are evidently related to the habit of fungus-feeding and present an interesting case of convergence. Varying frontal or declivital pubescence may be of secondary sexual significance. The armature consists chiefly of stout seta and spines on the tibise; lunar rugosities or asperities on the front of the pronotum, more or less strongly devel- oped; lunar rugosities about the base of the elytra, sometimes accompanied by an elevated elytral base; and teeth or spines on the interspaces of the declivity. The declivita! spines are particularly important in the classification of such genera as Pityogenes, Ips, and Xyleborus. An epistomal carina or process, and frontal tubercles, are developed in some species. The integument is nearly always strongly chitinized, except in such degenerate forms as the males of Anisandrus. The Sculpture. — The surface of the body is pitted with setose punctures of varied structure; the longer seta or hairs of the elytra are almost invariably borne by the interatrial punctures, and the minute pubescence from the strial punctures. The margin of the punctures is variably elevated into granules, rugosities or spines. The lunar rugosities of the pronotum and the declivital serrations are enormously developed marginal granules; they seem always con- nected with a setose puncture of which they are the greatly elevated front margin. The elytra are variably striate with the interspaces often convex, or carinate behind, and variably rugose. In addition to bearing punctures, granules and setse, the head is frequently very finely aciculate, and any part of the integu- ment may be finely reticulate. THE HEAD. 1 j^ The head is somewhat quadrate and prominent, visible from above in the Hylesininm and Eccoptogasterina, subglobular and more deeply embedded in 81 the strongly cunvex pronotum so as to be invisible from above in the Ipina and Micracina. It bears many of the most import, nt characters used in classifi- cation. The moiUhparta are only rarely made use of in the keys given in this paper, and need not be described in detail. The labrum is absent. The mandibles are powerfully constructed, without peculiar characters. The maxilisB and labium, on the other hand, present excellent constant and peculiar characters, some of which have been used in classification by earlier writers. The objection lYothormx Heao- MetAthormx thorax Hea4i Thorax Abdomen, SmtM* a*^. Fio. 2. — HTLCROOFa ToarKx. Fitcb; bioi viiw. Obioinal. Ant., antenna; EI., elytron, showins striae; El. dec., elytral declivity; Epis., epistoma; F. ci., fore coxa; Vr. front; Gen., gena; H ex., hind coxa; M. ex., middle coxa; Md., mandible; M. epim., mesepimeron; M.epist., mesepiEtemum; Met. st., metaaternum; Metepist., metcpistcmum; Mat., meHoatemum; Mx., maxilla; Pn., pronotam; P.m. st., proceic of the mesostemum; Scut., scutellum; Sut. St., sutural stria. •f ■I to their general use applies to most internal structures; that they can be examined only after careful dissection requiring a microscope and a certain skill in mani- pulation. The characters of the maxillae include the relations of the sclerites and the structure and arrangement of the setae. The lobe is spinose in most species, but fringed with long slender hairs in ambrosia-beetle genera. The labium is deserving of more attention than it has yet received in literature, and if it were not for the dlfiiculty in examination, would be used freely in these keys. The mentum, ligula, and palps bear excellent generic and specific characters. The eyes are feebly convex, usually elongate-oval, with the margin entire or with the front margin more or less deeply emarginate. In the genera Trypo- dendron, Xyloterinus, and Polygraphias, the eyes are completely divided by the median emargination (PI. 9, fig. 36). Polygraphus is otherwise very widely separated from these other two genera, and the condition of the eyes is an excellent example of convergence. The arUennce are geniculate, with a well developed scape, funicle, and a prominent club. The latter may be regularly segmented with transverse or i 3 •!' i ; 1 ■ 'i i , 1 1. ■ t' ,: 1 i ■ ' i' \ - II iii arcuate sutures on each side, Pityopthonu (PI. 10, fig. 22), or the inner margina of the segments may be thrust towards or to the apex of the club so that the segments lie obliquely and the sutures show only at the apex or not at all upon the inner face, Ipt; when in addition to this condition the club is thickened towards the base with the apical segments more or less completely telescoped, an obliquely truncate club is produced, as in Xykbonu, Anisandnu, Dryoccetet, Pityokteinea, and Orthotomicua (PI. 10, fig. 32), where almost the entire club is formed by the first segment. The distal segments are distinctly evident in Orthotomicua. In widely separated genera, Pityophthon^ and Eccoptogaater, the sutures of the club are very strongly chitinized, resulting in a partial or complete, distinctly visible septum. In a few genera the club is unsegmented, Chramtaua (PI. 10, fig. 36), Polygraphua (PI. 21, fig. 1). The funide comprises that part of the antenna between the Ist segment, called the scape, and the club. The Ist segment of the funicle, known aa the pedicel, is always enlarged; the remaining segments, comprising the outer part of the funicle (or the funicle of European writers) vary in number from one to six, usually widening towards the club. The number of segments in the funicle is usually a valuable character, but must be employed with caution since in some genera, Polygraphua, the number may vary in the same species. The scape is usually elongate, frequently strongly arcuate at the proximal end and clavate distally; sometimes short, Eecoptogatter (PI. 10, fig. 8); rarely much widened and flattened, Micracia (PI. 10, fig. 19). The anteims bear many important characters, used repeatedlv in the tables. They may often be examined satisfactorily with a good lens without removing them from the head, but very frequently it is necessary to remove and mount them in balsam.' The epiatoma presents valuable characters in the median lobe, variably developed, as in Phlceoainua; the dorsal process, Dendrodonua (PL 9, fig. 37, 38); the median carina, and the punctuation and pubescence. The margin bears a fringe of stiff, light-coloured hairs. The front bears important characters frequently used in the keys. Most important are the impressions, punctuation, granulation, median carina, and pubescence. Very often the sexes show marked difference in frontal characters. THK THOBAX. The pronotum is somewhat depressed in the Hyleainina and Eccoptogaa- tennce; usually strongly arcuate or gibbose in the Ipinae and Micracina, although in a few genera, Dryoccetea and Xylodeptea, the convexity is less pronounced. The characters present in our genera concern the shape, punctuation, asperities of the frontal portion, granulation, pubescence, sub-basal line or margination, and the condition of the lateral margin. On the ventral surface of the prothorax the length and concavity of the prostemum with the prostemal ridges are important, and also sometimes the punctuation of the lateral areas. »Pin the mounted beetle Becurely to a cork aiutle. With a needle, kept moirt with clearing mixture • .'i *^« »°*«™» 18 secured, work the antenna loose under a dissecting microscope, or a strong lens held in the left hand. Transfer the free antenna on the moist nee