l90l-1109-1OII1

TEXAS AGRICULTURAL EXPERIMENT STATION.

BULLETIN NO. 124.
October, 1909.

The Pecan Case-Bearer.

BY GLENN W. HERRICK.

Figz l.-—Case with larva partly exposed. Enlarged (original).

POSTOFFIOEZ
COLLEGE STATION, BRAZOS COUNTY, TEXAS.

AUSTIN, TEXAS!
vow BOECKMANN-JONES COMPANY, PRINTERS

I909

[Blank Page in Original Bulletin]

TEXAS AGRICULTURAL EXPERIMENT STATIONS.

OFFICERS.

GOVERNING BOARD.

(Board of Ihrcctors A. and M. College.)

K. K. LEGETT, President . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..Abilene.

T. D. HOWELL, Vice-President . . . . . . . . . . . . . . . . . . . . . . . . . “Jefferson.

A. HAIDUSEK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..-La Grange.

J. M. GREEN . . . . . . . . . . . . _ . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..Yoakum.

WALTON PETEET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Dallas.

E. R. KONE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..San Marcos.

L. L. MoINNIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bryan.

W. B. SEBASTIAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..Breckenridge.
STATION OFFICERS. _
H. H. IIARRINeToN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..Director.

W. C. WELlzolzNp . . .t . . . . . . . . . . . . . . . Slice-Director and Agriculturist.

J. W. CARSON . . . . . . . . .Assist.ant to Director and State Feed Inspector.

M. F IIAINoIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Yeterinarian.

G. S. FRAPS . . . . . . . I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Chemist.

o. M. BALL . . . . . . .; . . . . . . . . . . .  . . . . . . . . . . . . . . . . . . . . . ..Botanist.

——————— . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Ento1nologist

JoIIN C. BURNS. ., . . . . . . . . . . . . . . . . . . . . . . . . . . . . Animial Husbandry.

H. NESS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Horticulturist.

N. C. HAMNER . . . . . . . . . . . . . . . . . . . . . . . . .Assistant Research Chemist.

E. C. CARLYLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . “Assistant Chemist.

C. W. CRISLER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chief Clerk.

F. R. NAVAILLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..Stenographer.

A. S. WARE . . . . . . . .- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Stenographer.

STATE SUBSTATIONS.

. S. HOTOHKISS, Superintendent . . . . . . . . . . . ..Troupe, Smith county.
. A. WASCHIKA, Superintendent . . . . . . . . . . . . . ..Beeville, Bee county.

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NoTE.—The nzain station is located on the grounds of the Agricul-
tural and Mechanical College, in Brazos, county. The posto/fioe address
is College Station, Texas. Reports and bulletins are sent free upon ap-
plication to the Director. ’

THE ‘ PECAN CASE-BEARER.

Acrobasis ncbuZcZZa Riley.

The pecan tree, i11 Texas, is subject to attacks from at least two species
0-f so-called bud Worms, of which Acjrobasis nebulella, the case-bearer,
has been very forcibly called to my attention during the past season.
Evidently this species has been causing considerable loss in the State
for several years and Without doubt is the most serious pest attacking the
pecan. Professor Gossard, in speaking of the Work of this insect in
Florida, says “no other insect in Florida is more destructive to the
pecan.”

During the spring of 1909 it Was very abundant in the vicinity of
Cuero, Texas, and did a great deal of injury to pecan orchards in that
locality. In one orchard from Which the crop of nuts netted nearly
$2000 in 1908 the owner thought his crop in 1909 Would hardly pay to
gather owing to the injuries by this insect.

This pest is evidently Widely distributed in the vicinity mentioned and
has been the cause of serious loss to many pecan growers.

Hist01'y.—D'p to 1908 this moth had been considered a variety of
Zllmeola indigineila and is so listed in Dyar’s Catalogue of the Lepi-
doptera. It was first described by Riley in his Fourth Missouri Report.
He says a single specimen was bred from wild crab (Crataegus). Dr.
Riley also makes note of the fact that the same species was found by
him in the cabinet of M. J. Lichtenstein, Montpelier, France, it having
been taken in that vicinity. In the tenth volume of the Proceedings of
the Entomological Society of Washington, 1898, Dr. H. G. Dyar de-
scribes this pest as a distinct species, Acrobasis nebuleillai Riley.

Distributionr-The insect seems to be quite widely distributed and
has more than one food plant, although the hickories seem to be prefer-
red. It is recorded by Riley from Missouri; by Scott fro-m Atlanta, Ga;
by Boll from Texas; by Pratt from Kerrville, Texas; by the Bureau
of Entomology from Blackshear, Ga; by H. G. Dyar from Rhinebeck,
N. Y.; by Gossard from Florida, and by myself from Cuero and College
Station, 'l‘exas~. It will be noted that Dr. Riley found it in France, but
“whether indigenous or imported from this country is a question yet to
be solved.” It is probably widely distributed all over the South wherever
the pecan or hickory grows.

Food pZants.——Dr. Riley bred a single specimen from wild crab and
several specimens from hickory and walnut. Gossard bred it in abund-
ance from the pecan in Florida, and I reared many specimens from the
pecan from Cuero, Texas, where it was very abundant and doing serious
damage. High found it on wild hickory near College Station.

Nature and extent of injury.—'l‘he larvae injure the leaf buds prin-
cipally as the leaves begin to appear in the spring. The over-wintering
young larvae congregate at the ends of the young branches and begin eat-
ing the young leaves as fast as they com-e forth. In other cases where

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the young leaves get a start the larvae tie them together with silk and
form their cases inside of this blackened, ragged mass made up of cases,
silk, excrement, and wilted. and dried leaves. Often a tree will struggle
along for some time trying t0 put forth its leaves. On March 31st, an
infested orchard at Cuero was visited and the larvae were found in large
numbers. Hardly a branch or a twig was found Without from one to a
half dozen or more of these minute larvae, some concealed in their cases
While others Were feeding, mostly down the center of the tender leaf
stems, and in some instances had actually bored their Way into the Wood
of the twigs. This caused the twig to die back at the ends as though
blight-ed. From one to twenty of the little cases were found upon the
distal end of a single branch, thus making possible hundreds upon the
larger branch. The young trees, that is, those four or five years of age,

Fig. 2.-—Ends of branches showing Work of larvae (original).

had great masses of these little cases upon almost every branch. Many
of these larvae were burrowing into the ends of the twigs. The larvae
were in such numbers that practically all the twigs infested were leafless
and showed little vitality, with nothing but the blackened masses of cases
and debris at the ends of the branches (Fig. 2). A few larvae are often
found scattered among the well-developed leaves whe-re they will tie three
or four together with their web and build their individual cases in be-
tween the tied up leaves. The injury is not wholly confined to the
youngest leaves, for' the older, well-developed leaves are often eaten full
of irregular holes.

Moreover, the flower buds are often attacked and seriously injured.‘

On the 7th of June I received a small b-OX of young nut-s just set, each
of which had been bored into near its base. Among the nuts which had

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been partly Webbed together was ;a. full-grown larva of A. nebulella.
Within eaeh of two other nuts I found a dead larva. The kernels were
completely eaten out, leaving only the hollow shells. I am convinced that

Fig. 3.——Case enlarged and natural size (original).

 

    

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Fig 4.—A, larva; b, case fastened to petiole of leaf (original).

A. nebulellawvas the cause of this injury, although the larvae doing the
work were considerably later in realehing maturity than those we had
reared. from Cuero, "Texas. However, it is likely that the majority of the
larvae mature later than those did in our laboratory.

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T he CCl8€-.——-Tl16 cases are made of frass or pellets of excrement tied
together with silk and lined inside with silk. The cases of the immature
larvae are often curved, reminding one strongly of the cases of Mineola
incZi-gineilla. As the larva increases in size and nears maturity the case
becomes straight and always noticeably enlarged in the middle (Figs.
1 and 3).

The distal or unattached end of the case is usually slightly larger than
the fixed end, but not conspicuously‘ so. The larva when feeding pro-
trudes its body through the opvcn end of the case (Fig. 1), but ‘holds to
it most tenaciously with the prolegs when any arttemapt is made at re-
moval. When a young larva is removed from its case and transferred to

another position it first of all begins the construction of a new habita»

 

 

Fig. 5.—Moth twice enlarged and natural size (original).

tion. The case is exceedingly tough and very difficult to tea.r apart.
When the larva is full grown its case averages from 16 mm. to. 2O mm.
in length.

lVhen the larva is ready to pupate it moves out among the well-de-
veloped leaves and fastens its case securely to the petiole by a. foot-
stalk.-of strong gray silk (Fig. 4, b). They also cover the case on the
outside xvith a layer of silk, thus giving it a grayish appearance, and then
close up the free end, later changing to a pupa within.

On April 1st, I opened. a case that had just been closed- and almost
immediately the disturbed larva began industriously spinning up the
opening. By the morning of April 2nd the case had been completely
closed and made ready again for pupation.

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The 11t0th.—‘The moth has a Wing expanse of about 15 to 18 mm. and,
in general, is grayish in color (Fig. 5). The head between the eyes, the
thorax, the patagia, and the proximal third of the wings are dirty white.
On the front margin of each front wing about one-third of the distance
from the proximal ends is a triangular patch of dark scales, purple in
some lights, and just beyond this patch, in a lighter area, are two dark
spots one behind the other (Fig. 5).

When the moth alights the wings lie roof-like along the abdomen with
the anal margins slightly overlapping. In this position, the head, thorax,
and forward part of the body are conspicuously light gray with this area
sharply defined posteriorly by the meeting of the dark patch of scales
on each wing. They frequent the weeds in the orchard and the debris
around the bases of the trees, among which they hide and elude one
when pursued.

The larvar-The full-grown larva measures 12 to 15 mm. in length.
The body is dark green and the head dark brown. The prothoraeic
shield is lighter in color while the mesothorax has a pair of shiny black
tubercles, one on each side. The second, third, fourth, fifth and last ab-
dominal segments each bears a pair of prolegs (Fig. 4, a). Each proleg
ends with a circle of minute hooks which enable the larva to cling
tenaciously to its case. The thoracic legs are black.

The pupa.-—It has no characteristic or conspicuous markings, but is
shiny brown in color and varies considerably in size, measuring from
7 to 1O or 11 mm. in length.

Life h{story.—Unfortunately, I was obliged to leave Texas before
the egg-laying period of the moth occurred and hence have not seen the
eggs, and, so far as I can find, no one has described them. Very likely
they are laid on the leaves. Gossard says “Its summer history agrees well
with that of its twin relative, the leaf erumbler of the apple and other

orchard trees, illineola iindriginclla, the eggs soon hatching after which

the young caterpillars commence feeding on the younger leaves, espe-
cially those just opened at the terminal ends of branches.” We made
very careful search for the eggs up to the 10th of June, but as only a few
of the moths had appeared in the field by this time it was probable that
the eggs had not yet been deposited. The young larvae live upon the trees
all summer, but do not attain a very great size nor commit conspicuous
injury owing to the large amount of xvell-developed foliage. As already
stated, the cases of the immature larvae are more or less curved. Prob-
ably the larvae attach their cases to the trees before the leaves fall in the
autumn and remain in this situation all winter. The fact that they
appear in such numbers and with such suddenness in the spring just as
the buds begin to put forth shows that. they must winter over in great
abundance. They mrust be quite inconspicuous on the tree, and I regret
that opportunity was not afforded me for observing them during this
phase of their life history. In the vicinity of Cuero the larvae become
active in March and by the middle of this month their depredations are
noticeable and serious. It was on the 24th of March that I received the
first large batch of larvae. It was on April 1st that I found the first
larva closing up its case for the formation of a cocoon. The pupa was
not formed, however, until after April 8th, and the moth did not appear
until May 2nd. Very likely this larva was hastened into pupation by

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the lack of a food supply. Other moths appeared as follows: May 10th,
May 11th, May 7th and May 9th. All of these were in ‘the laboratory,
however, and their food supplies were rather irregularly and scantily
furnished. Goss-ard says that “the moths appear from the 1st of May
until the 1st of July, the bulk of them coming as a general rule during
the first half of June.” It is quite probable that they appear in Texas
also over so long a period. The larvae among the young nuts received
by me on June 7th would indicate this. It is quite likely, too, that the
larvae kept by us in the laboratory were hastened into pupation earlier
than they would have been in the field.

iVatuirat enemies.—.[n my rearings of the larvae no parasites were bred
and no natural enemies were observed in the field with the possible ex-
ception of one species of spider which Mr. High observed apparently
sucking the juices of a young larva. Gossard says that “a Tachinid fly,
two or three ichneumon flies and a very minute hymenopteran” emerged
from the cages in which he was breeding the larvae and pupae. Of these
he identified surely only Pimpla conquiisttor and Sptlochalcts vtttata. He
further says that “the cumulative benefits of parasitic attack were illus-
trated by a few trees -on the Station grounds, which during April and
May, three years ago, were well-nigh unable to get into foliage; for the
past two years they have been in much better condition, due almost
wholly to parasites.”

Control by spraying with arsenate of Zead.——A small orchard of pecan
trees at Ouero which was very badly infested with the Acrobasis offered
a splendid opportunity for trying the effect of a thorough spraying with
arsenate of lead. This orchard consisted of probably two acres of trees,
and around the outskirts of the main body were thirteen trees varying in
height from six to ten feet. Since these trees were distributed in such a
manner that a few of them were standing on each side and end of the
main body of trees, and since they were all badly infested and of medium
height they were selected for spraying, while the main body of trees in
the middle was left as a check.

On the 5th of April Mr. M. M. High sprayed these trees with Dis-
parene, 3 pounds to 50 gallons of water, using a common barrel pump
with one lead o-f hose. It was raining while the first two trees were be-
ing sprayed, but these were gone over again after the rain had ceased.
All of the thirteen trees were carefully and probably more thoroughly
sprayed than would ordinarily be done. \

On April 27th the trees were carefully examined to note results. Pains
were taken to examine the highest branches, using a ladder when neces-
sary. On tree No. 1 two living larvae were found and many shriveled and
dead ones. No more living larvae or pupae were found until tree No. 10
was reached. This was the tallest tree and difficulty was experienced in
reaching the highest branches when it was sprayed. On this tree one
living larva and two pupae were found on the extreme end of a tall
branch which was probably not reached with the poison.

The trees were in uniform leaf and in no way resembled the picture
that they presented on April 5th. The-trees lo-oked healthy and vigorous
with their new crop of leaves. It will be recalled that these trees were
very badly infested on April 5th, and present-ed a most discouraging ap-
pearance.

_1()__

The owners considered the experiment. a co-mplete success.

Recontmendatrlonsi—One application of the arsenate of lead should be
made considerably earlier than the foregoing. It should be applied as soon
as the buds burst through the bud-scales. Another application later may
be necessary.

An cwperivncnt (against the pecan bud moth, Proteopterya: deludama,
and its beat-ring 0n the control of the case-b,erarea".—Froim an experi-
ment made in a large young pecan orchard at Jacksonville, Texas, to con-
trol the bud moth it would seem that this pest, at. least, may be held in
check by a. Winter spraying with the lime-sulphur mixture. The minute
larvae of this m|oth Winter over in their tiny cases snugly hidden away
behind the buds. That is, usually between the buds and the branch.
This pest was present in the orchard during the spring and summer of
1908 and caused serious injury. I found the cases containing the larva
present in considerable numbers on the trees in February, 1909. Early
in February we sprayed every other row of this orchard very thoroughly
with the lime-sulphur mixture (20-15-50 boiled forty-five minutes).

‘Later on, the owner fearing an outbreak of the pest in the spring dared

not leave our check rows and sprayed those also. Fortunately, he left
several hickory trees at the side of the orchard which he had budded
with pecans. These, he writes, were badly injured by the bud worm in
the spring. His main orchard, however, was free from any injury of this
pest up to April 4th, and he writes as follows: “I am freely persuaded
that the lime -and sulphur spray last winter was a perfect success in de-
stroying the pecan bud worm on my farm.

“I have carefully examined twenty trees three times a week for my
bud wrorm, and never saw any sign of them until the 19th of March, and
that was on my hickory-pecan budded trees where I never sprayed at all
all winter. I believe I shall have to spray these trees every two to four
weeks all summer.

“There has- been no sign of bud worm on any of my sprayed pecan
trees.” 

From these results obtained with the lime-sulphur wash for the bud
worm, I am of the opinion that the case-bearer A. nerbulella. might also
be controlled in the same way. If these two most serious pests of the
pecan could be controlled by the same material applied at the same time
for both pests it would be a distinct advantage. Besides, the lime-sulphur
wash is a splendid fungicide and may also prove of aid in the fight
against the pecan Phylloxeira, another pest of this tree.

Acknowledgments.—I wish to acknowledge my indebtedness to Mr.
M. M. ‘High, a student in the Entomological Laboratory, for his observa-
tions made in the field and for his enthusiastic aid in carrying out the
spraying experiments at Cuero under my direction.