7. 5; W \. ---i,--_
S CIRCULAR No. 8, REVISED EDITION. i 0E_ 1 l.'--u i- ,i.- r V:. 1"O.
United States I)epartm i_ E1 t
BUREAU OF ENTOMOLOGY, -' -
L. 0. HOWARD, Entomologistm and Chief of lurr a "
________ 14 ,
THE IMPORTED ELM L, AF-..EEt.b.
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GENERAL APPEARANCE AND METTIOD ()I-' 1 (ORK,
The chief insect enemy of the elm is thew impniprtcil ,lin le f-1,,ilh..
the larva and adults of which frequently so ,i-li.iigr i liIr tr'c- hI, t,
render them useless for shade anid hiltdeous ralhtier t imnii ,rnn, miii iil,
The beetle-a small. 'ellow i-l-i-hrvi iiii.t-.',ajipi, ir- irt ainl fill,
the leaves with snimall irregular h,,le., \liil, (' t4 il,,in ifrh l,,rI .t
slug-like yellow and black larv kl' .klltimizei.' ih," leav,', in irr,.miilar
spots between the veins, working uin hotlhi .'Irfai v,. Iut ciliellY ion
the lower side, causing thle leaves to a.-simine it ,r, Iir,iwn [appa r-
ance, to curl, andi ultimately to fall. 'rlie -.ciiiiiI rop
DISTRIR T INX.
This leaf-beetle is a well-known def,,linatr of .lin tret,' in E'lr.p,'.
It is especially abundant in Franc-,. sil h.ni ('rn ivY. J ill[ .\At ri.n.
and to a lesser extent in Itily. ('orsiea. anil Sar, linia. It wa. Irniiiit.
to the United States about 1: 7 lt Ilaltinr,'.. Md., nmdl g-ranliill
spread north and south until at pr''i-ent it ratlir- :tf far -l1mi1i .1i
Richmond, Va., anti as. far n'irth as -m.it wern Nt-w li;,nphin'l ,111n
the Atlantic seaboard and Itlia.a in rentri I Nw- York. Fir ilni'V
years it confined itself to tli't, Atllnnati' .-l.h arn, i. t liia- n,, pbt -n'. I
the Appalachian range and %ill proimiillv ,spran.il Ihr,,ughll 0i' We-l.
conforming in general to the limit-s of thie I'ppar .Aiiztrnl liftr zunt.
NATURAL IISTOnY' AIND HiRllAhJ.
CTi.ARA, rER. i.T"r 'II rIrIF i i:' : %r -T. I'-.:;
The insect occurs on the trees in three different %tw_-,r-, and tile
fourth stage is pasetied on r under lth surfa.-' of fithi,' griuind at the
base of the tree: i. e., the egg, larva, and beetle on the tree, the
pupa in the ground.
5.3931- -t'ir. %-4)3
The adult, or beetle, is slightly over a quarter of an inch long, gen-
erally of a yellowish or yellowish-brown color, with three somewhat
indistinct brownish-black stripes on the wings. It is shown natural
size at c, and enlarged at k, in figure 1.
The eggs are placed on the lower side of the leaves in vertical
clusters of from 5 to 20 or more eggs to each cluster, closely
arranged in two or three irregular rows. They are oblong-oval in
shape, tapering to a rather obtuse point, orange-yellow in color, and
FIG. l.-Elm leaf-beetle (Galcrucella luteola i: a, e, Eggs; b, g, larvaee: c, k, adults; f, sculpture of egW.
h, side view of segment oi larvai, a, dorsal view of same: j. pupa; i, portion ol elytron of adult; a, b, c,
natural size: gj, k, somrewhnt enlarged. c, hA, i, 1, much enlarged, J, highly magnified. (From Riley.)
the exterior surface is covered with beautiful hexagonal reticula-
tions. They are shown natural size on the leaf at a, and much
enlarged at c, with the reticulated surface still more enlarged atf.
The larva is elongate, reaching a length of about half an inch, and
when newly hatched is nearly black. As it increases in size it be-
cnmes, with each shedding of the skin, more distinctly marked with
yellow, and when mature the yellow predominates, occurring as a
broad dorsal stripe anti two lateral stripes. -The larva is represented
natural size on the leaves, and somewhat enlarged at g, with por-
tions still more enlarged at h and i in the figure.
The pupa is uniformlndv light iraiiiir-Vnllw, 'ival in -hlip', "irinigh
convex dorsally, andi a little ovr a 1'ttl'rltr ,f iii iii iiilrgl h. It
is shown in the illih.tritin it j. eJl,,rg.r.
The egg sttg, lusts b OLIt t %ir.k, tl lie Ilrvi iinritiaillv lifteeii tI,
twenty days, andi the pupI1 -ix to iii ia\..
NUI'MitF tF. OP' i, i ItIltm l I I I %' 1 1 ,iIt 11 1 Vt
In the more southern rin,',, if tli- in-rit, iirliiiin Mairylanirid.
Virginia, Delaware, ,ntd mnu4t tf New *ITr.-'\, tliri' arn, twii lii, il.,
annually, with inoc'caisi, Itn l siinalrr tliii r I.iiinratin. i-'itrthlir ni rt Ith.
Including northern New or.l-e'y, I ,,ii. I lritn, N.w Y,'rk Sliate, 1nId
I Connecticut, there ii in gvir'l int ,in' vwll-markil )ril. with
sometimes a supplement al ,r paiirtial -econt I 1riail.
Throughout the tcid ilile-hr(ithll Iarez ih, lv1rl.cs inake tl,,ir ap-
pearance in spring abltut (lith e iidilli' m'i April, l 'gir iing u11 <,ii1i4 (jilt
before the elms hayv, put out thItir ilt' Vcs, cotillnlin n, ,>n tilt. trees
through May, and perishing son after e,-Iaying is finished. The
eggs of the first hirml are ,lepo',Ited I ,il riI.I. May a1 il into .T1une, tthe
larva of this brood occurring fr,,nit earl v in M\Ia tlhiritIloii)tl J.une.
Pupation takes place tdiirini .J nTi arid .July, anI Ietl'ts If the .sec lnid
orsummer brood emerge during .Iily an- d into A.unist. Tlite eg.s for
the second brood of lairvaiv are depo'sitedi liv thlese hlwt'Ir. from tlie
Middle of July througliout August, and llthe lriv,' ,f tIhe second
brood skeletonize thlie second growth if elm ]iile- ,lrinii tin' hlit Iter
part of July and Autgust, tlie later specimens icci irriniiL up i ( )ctober.
Pupation occurs chiefly dhrit A.imiist ant1!d Spt lil)er, tlie beetles
appearing from the last of Auiigist thi ruigh,,it Sipttciler, antd enter-
ing winter quarters during September ani ()Octi,,iber.
In the single-brooded r-egios thlie beet lei; dn nt al)pear in spring
until the last of May, and, in general, the pleriodl- art' fiUllv a nitli
later for the different st ages than in lie smit hern list ri't s, tie beetle s
of the summer brood transforinirin most alndiutlalv ,ttniit the lIt
of August. After feeding on thlie leaves a llitle whiilh, and Iloing verve
inconsiderable damage, thev go into winter cluiarters durini- Augu-st
and September, remaining doormant eight or imie miontit hs.
HABITS OF A..RV.E- AN. D IIiiBERNATiIN IF .M'l'LT.
The larvie from eachli batch of egg,- feel to-etiher fr a timrie, bit
ordinarily become separated anl scatt'lered later, e.-pec.'iilly withI a
scantiness of food. ,Wheti full grown thie l:tir\', iiiaill- crawl i iwni
the branches to the trunk anil then to the griunld. piilpatiig alri,,-
immediately on or very near t'lie surface ,f tle -,i[ aiti thlie
base of the tree. They are apt to seik partial pruttctio about
grass bunches, but frequently accuniulate ill Vnx.-es. c'.x)osed on tile
surface in such a manner as to make a striking yellow carpet about
the tree from a few inches to a foot or more wide. With very large
elms, however, many of the larvae are shaken off by winds or fall
directly to the ground, sometimes fairly covering the surface over an
area equal in diameter to the limb expanse of the tree.
Hibernation takes place in the adult state, both where there is but
one brood and where there are two. For this purpose the beetles
frequently enter houses and barns or outbuildings, sometimes assem-
bling in such numbers that it, is possible to collect them by the quart.
They also enter cracks in posts, telegraph poles, fences, etc., or where-
ever they can secure partial protection from winter storms.
SUSCEPTIBILITY OF DIFFERENT ELMS
European elms seem to be especial favorites with this insect, and
this would naturally be expected from its European origin. Its
preference for the European elms is especially noticeable where these
are grown in conjunction with American elms, the former being
frequently entirely denuded, while the latter remain practically un-
injured. In general, the coarser-leaved sorts of elms are distasteful
to the beetles, and the smooth, thin-leaved varieties are especially
subject to attack. The American species, Ulmus americana, is nota-
bly exempt, and this, together with the general immunity of other
American species, is a strong argument in favor of restricting planting
to our native sorts. All species of elms, however, are attacked more
or less, and in the absence of sufficient foliage of the favorite varie-
ties the injury to less palatable sorts becomes almost equally marked.
There are no effective American natural enemies of this insect.
There exists in Europe an egg parasite which from time to time is
very effective. This is a minute chalcidid, known as Tetrastiehus
xanthomnielene Rond. After several years of fruitless effort this
insect has been brought to the United States during the summer of
1908 by Doctor Howard, through the kindness of Professor Valery-
May6t, of Montpellier, France, and has been distributed at Cam-
bridge, Mass.; Melrose Highlands, Mass.; New Brunswick, N. J.;
Ithaca, N. Y., and Washington,, D. C. It bids fair to become a
strong assistant in the fight, against the elm leaf-beetle.
In nearly every stage of its life history this insect is easily sub-
ject to treatment. The best means against the adults and larvs
c,,n.ist in the use of arsenical poisons in the form of sprays on the
foliage. The ailults, for Ithi, week ior Iw%-i aftir 'iiergiing, fild n ill,
newly expanded Ifrlmug, niil i spiratiing with Paiin lri 1r"ll 11,r ,,ii.r1
airmenical will dr, rnv ti' gl'ri't mnji iria.v ,,f tli.n-i. lE-I,,,iil pniui,
should be taken lo atv,,t ', i ll 11hv d ii r li, f ll, ih ill.,cl: In l1lii-
stage, in lurdteor t r IIt'vt' n I ill., pirlid iliifigiri'Iii t i f u if tr.rs, \\ lirli
will result if the' Inatter ti lie tll:iv i .,I lilli ili' lurvi- l'giin too jil tiar.
If rains intel'rfere with -priyil g for tIl ltltifll-, -,r if if Inv' il''Of.''l.
the trees should ie spr vi'dI will ni-'uirnl.i priimilltly in ii fir'If
appearance of hlih larvi', iii Iand l itu, iii ,,ii pwli'ii- rinewi la wi,'Ik
or ten days liter, esp'it'illYl if rutiii-' lil'-'l iiilrrvtfiilu .
Paris grpetn is I le esl h ist e1iii.lil, iiil ill% In' ,',f'v ,lis"l (-i fltiii zl
the rate of 1 ptouil tII front li ii1 1.'igi 'itll'iti' uf lvi fr'. If lw lilhlif
purple be used, an 1ilnoIulti-nf liiint' i'jinlll t., tlit' ( pii.ln in wPiight shltiilil
be added to cininir, witli itiv fret iirMe'nir uinl I)rvt'vnt scalding ,f
foliage. The liquid shliludl I' pplii'l bIv .itriiung force pump, i
long hose, and a litozzlh, suth lit- ti't VeriiintirI 'ir Nix'nt, which will
make a fine mist-like .spray. In .spryiiinr. fllr tlie lIrvai it is v'er -
essential to thoroulghly we%- ti' Iti)wer sitl I If fth' lli'-s, (in wicih tli'v
principally feed. In the ci'lt' of llc illi-, lii.s i snut .l nlt',e.i's '"y,
because they eat tliet entire su liataict' of tli, leaf. illni will g't lhli'
poison from either side.
On elmnis 15 or 20 feet in ltiglit theI trtittlinntni can lit tnila front
the ground or fronit a \vwagoin. For lirger elmni, it will ib necessary !II
climb thie tree, using a1 ht'-e fr' in "0 lit lli) feet \'ng, andl directing
the spray by this means into tie upper branclies. By removing tile
spray tip from a aInrge ize Nixon nzzle, in orhiler to gt at direct dlis-
charge, the upper branches of colltipa ritli ely tall trees mnaYv be
reached anti sprayed in ia mniore or less satlisfactorv maniiner. In the
case of very large elms in city parks or streets ile ist, of stronger
apparatus may be advisable, such as a lire eiruint, or teaim pump, inlld
a larger nozzle, such as a gratiduating spray tip. ct'iplilhi of lirowing
either a direct stream or a spray. I)uring spraying Ilit, poison should
be constantly stirred to prevent it from settling, tp ltie botl iin -f lit
The first effort should be to destroy y thie beetles and larv'; at their
earliest appearance, to save the trees for (lthe current year. Sorit'-
times, however, lairv:-i in the top)S of tall trees will escapt'e, an1. when-
ever from inefficient spraying or iie'lect thev tire allowed Ito reaclih
maturity, a strong effnrt should I be made t Io tdIe-trov tlile inisect whlien
it reaches the ground to transformn, anid tlhus limit or prevent dain-
age from the second brood or in the following Vclilr. flitn' cingre-
gating of the larve' for pupation, frequently in enmrnii.s inuilii-ers,
immediately about the b)ase.of the tret, innik's thi'ir dl'trurt'lion in
this situation comparatively easy. This Imay be acciiiiplislied either
by wetting them with boiling water, or with kerosene emulsion diluted
about four times. Frequently they may be collected by hand or
shoveled up, and burned.
Remedial treatment is much simpler in the northern area of the
range of this insect, where it is single-brooded, and becomes more
difficult in the southern districts, where the number of broods is
doubled and the appearance of the insect becomes somewhat irregu-
lar, continuing practically throughout the summer.
Secretary of Agriculture.
WASHINGTON, D. C., August 31, 1908.
UNIVERSITY OF FLORIDA
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