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 Circular No. 4, Second Series. 
 
 I oited States Department of Agriculture, 
 
 DIVISION OF KNTOMOLOGY 
 
 THE ARMY W 
 
 / ■ 
 
 01 mi: \i. IPPE \i: IN( i: \m> mi i HO 
 
 In the months of M.i\ and June, and S< 
 wheat, oats, and other small grains, corn, 
 blue grass, and other grasses, but seldon 
 clover, are occasionally overrun by mul 
 naked striped caterpillars about an inch a 
 
 let l«»nir and a quarter Of an inch in diaim 
 
 full-grown, rather dark in appearance and i 
 Bembling Fig. 1. '[\wy usuallj travel in one 
 from one field to another, destroying *hecrop •■; 
 go. They bav< abil >' - 'n.'e . the stalks 
 
 and cutting off tlu m<a by grass and of the 
 
 small grains. 
 
 MM Klltl I [ON 
 
 The army worm seems to be an indigenous North 
 American insect, and <>n this continent is tnosl 
 abundant in the United States easl of the Rocky 
 Mountains. Isolated specimens have been found 
 in KiiL'land and South America, and the moth has 
 been captured in India. Java, Australia, and V w 
 Zealand. It is nowhere known ,-i- an especially 
 destructive species, however, outside ol the I oited 
 State-. The region iii which it especially flourishes 
 extends from eastern Eowa to Maine and from 
 northern Texas to northern Alabama. Easl of the 
 Bine Ridge Mountains it^ southerly range as an 
 injurious species extends only to northern North 
 Carolina. The moth i- often captured outside 
 these limit ^ and frequently in considerable num- 
 bers, hut the caterpillar does not seem elsewhere 
 to be a factor in agriculture. 
 
 ARJIV 
 
NATURAL HISTORY AND HABITS. 
 
 The adult Lnsecl is a brown moth with a white spot on the center of 
 each fore-wing, as indicated at Fig. 2. The eggs are very minute and 
 white in color, round, and are laid in strings of from 2 or 3 to 15 or 20. 
 They are pushed by the ovipositor of the female moth down into the 
 inner base of the terminal leaf sheaths of grasses or grains. (See also 
 Fig. 2.) A strong effort is apparently made by the female moth to 
 conceal them. They are laid most abundantly in the thickest tufts of 
 grass which customarily spring up in pastures over spots where cattle 
 have dropped. In the vicinity of old fodder stacks the grass usually 
 glows high, and tins also is a favorite place for egg-laying. The moths 
 do not confine their egg-laying operations to such localities, however, 
 
 and the eggs have been found in old 
 cornstalks, thrust under the sheath, and 
 even under the bark of old cedar posts. 
 The eggs arc hatched in from eight 
 to ten days and the young caterpillars 
 feed for a time in the fold of the leaf, 
 growing rapidly, and finally consum- 
 ing entire leaves. 
 
 Under ordinary circumstances, and 
 when not present in great numbers, 
 the larvae feed mainly at night and in 
 damp cloudy weather, remaining hid- 
 den during sunshiny days. In this 
 respect they resemble in habits the 
 closely allied cutworms. They reach 
 full growth in three or four weeks, burrow into the ground, and 
 transform to the brown pupa? shown at Fig. 2. In this condition 
 they remain in the summer time on an average about two weeks, 
 when the moth again appears. 
 
 The number of generations each year varies with the climate and the 
 season. There are. in the more northern States, two or three genera- 
 tions, and perhaps six in the more southern States. 
 
 We have said above that the insect normally feeds by night and 
 hides by day. and to this habit is due the fact that, although the army 
 worm is present every year all through the region especially indicated 
 in a previous paragraph, it is only noticed when it becomes excessively 
 abundant, and this occurs usually only at intervals of several years. 
 
 With a favorable succession of seasons the insect multiplies in geo- 
 metrical ratio, and at last becomes so numerous as to necessitate migra- 
 tion for food. It then travels and feeds during both day and night, 
 and it is then that the insect becomes very injurious and that reports 
 of great damage are heard. 
 
 The insect passes the winter normally, as do most of the related cut- 
 worms, in the half-grown caterpillar or larval condition. In the South 
 
 Fig. 2.— The Army Worm {Leucania uni- 
 puncta : Moth above, pupa below, and 
 eggs in natural position in a grass leaf 
 all natural size, i From Comstock.) 
 
8 
 
 it also undoubtedly hibernates a .1 moth, and there i- some evidence 
 thai it ma) pass the winter occasionally, although exceptionally, in 
 the egg state. 
 
 The injurious brood ma) be the first, second, or third. The over- 
 wintered larvse maj occasionally be so abundanl as to attract notice, 
 hut in the majority of cases it is the offspring of these overwintered 
 indiN iduals w Inch cause alarm. 
 
 In general it ma) be said that the worms arc more apl to make an 
 injurious appearance in a rain) spring or earl) summer following a 
 Beason of comparative drouth. The presenl season (1894 bears out 
 these conditions in the Eastern States, and a- a matter of fact the 
 arm) worm has been more abundanl in certain eastern sections than 
 it has been since 1888. 
 
 REM] DIES Wl» PEE\ I.N I i\ I. ME \-i RES. 
 
 There is never an) demand upon this office i"i remedies for the 
 army worm until it i> almost too late t<> do an) immediate good. 
 The re arc certain old-time measures which ma) he adopted to protect 
 certain licit I - from advancing armies, like t he plowing of a furrow with 
 its perpendicular side toward the field to he protected and the subse- 
 quent dragging of a log through the furrow to keep the earth friable 
 and kill the worms which have accumulated in the ditch, and another 
 is the sprinkling of a -.trip n( pasture or field crop in advance of an 
 army with Paris green or London purple in solution. In fields which 
 the caterpillars have already entered there i- little which can be done 
 for their destruction which does not also involve th< destruction of the 
 crop. The fields may he sprinkled by mean- of a broadcast sprayer 
 with an arsenical solution, or they may he rolled with a heav\ roller 
 where one i- at hand and the ground is level, or a flock of sheep ma) he 
 sent in, which will result in crushing most of the worm- b) trampling. 
 
 In the great majority of cases, however, these latter measures arc 
 unnecessary, for the reason that nature herself almost always take- a 
 hand in the red net ion of t he excessive cumbers of the insect, either by 
 unfavorable weather conditions or by the excessive multiplication of 
 natural enemies and parasites, so that it i- extremely rarely that we 
 hear of one army-w orm outbreak immediately following another. 
 
 In general, therefore, it may he -aid that, a- soon a- the worm- are 
 discovered to he exceptionally numerous in a given held (and a- a 
 matter of fact, they are at first almost invariably restricted to the 
 immediate neighborhood of some definitely limited, permanent breed- 
 ing place I, all energies should he devoted to the protection of the sur- 
 rounding crops by the means mentioned above, and the destruction 
 of the worms in the fields first attacked may he safely left to the last. 
 
 There are many localities in w Inch the army worm i- never -ecu. or, 
 rather, is never known to ho injurious, and these localities owe their 
 exemption undoubtedly to the unconscious use of preventive meas- 
 
ures. Clean cultivation, rotation of crops, cleaning up fence corners, 
 close pasturage, the burning over of waste grass land in spring or fall 
 arc all preventive measures of great value, since, where these methods 
 are in vogue, the army worm will never he able to get a migratory- 
 start, or, in other words, it never becomes so abundant as to necessi- 
 tate migration. 
 
 Bearing in mind the fact that the insect breeds normally in rank 
 grass, such as is usually found along the edges of swamps (not in 
 swamps, for the insect must have comparatively dry earth in which to 
 pupate) or in accidentally overfertilized spots in pasture lands, and 
 that it feeds normally only upon true grasses, the farmer who has 
 once suffered from army-worm attack may easily prevent its recur- 
 rence by winter burning or by rotation and clean cultivation. 
 
 In cases where the worms have already entered a valuable field of 
 wheat before the farmer has become aware of their presence, and too 
 late to render ditching of any avail, some little good may be accom- 
 plished if the majority of the worms are full grown, or nearly full 
 grown, by the old method of "dragging the rope." Two men, each 
 having hold of the end of a long rope, are sent through the field and 
 the rope is dragged over the heads of the grain. The backward jerk 
 of the stalks jars the caterpillars to the ground, and they are unable to 
 ascend to the heads again for some little time. This is a laborious 
 process, however, and has to be repeated almost immediately. It is 
 only to be undertaken where the number of worms in a field is com- 
 paratively small and where these are, as before stated, full grown or 
 nearly full grown, since in this case they will stop feeding and enter the 
 ground in a day or two. 
 
 NATURAL ENEMIES. 
 
 There is almost no prominent injurious insect in whose economy 
 natural enemies play a more important part than the army worm. We 
 have said above that in the great majority of cases actual destructive 
 measures against army worms which have once taken full possession 
 of a grass field are hardly necessary. This is because of the fact that 
 generally not more than one worm out of a thousand escapes death 
 from parasitic or predaceous insects. Where the army worm follows 
 its normal habit and feeds only at night, remaining hidden during the 
 day under the surface of the ground at the base of some tuft of rank- 
 growing grass, it is protected from these natural enemies, but when the 
 migratory instinct drives it forth and perverts its normal habit, caus- 
 ing it to march unprotected during the day. the swift-breeding tachina 
 Hies attack it at once, multiply most rapidly, and in connection with 
 1 1 -^ other parasites and with the predatory ground-beetles, reduce its 
 numbers once more to the noninjurious point. We have said this is 
 generally the case: then 1 may he exceptions, but we have never seen 
 "lie. ft is important, however, for the farmer to be able to recognize 
 
ire 
 
 ; Ml I I. I V m\ v- 
 
 i LI . writ] 
 pup 
 
 of mi Army 
 \\ onn with I u 
 
 rhal onlargi 
 
 Reappearance of a parasitized worn, asm this wa 3 his confidence in 
 
 the ful ure max be restored 
 
 \\,. 3 hoM ai Fig. 3 the head and from segments ol an arm) worm 
 tearing eg*rs of the red-tailed tachina ll> ^ Vemoriea leucm 
 eggs are white, oval, less than one-sixteenth ol an inch long, and 
 glued fast to the skin of the caterpillar, 
 usuallj on the back .-I' the fronl segments. 
 From half a dozen to fifty or more of these 
 eggs uuw be attached to a single caterpillar, 
 and from each hatches a maggol which pene 
 trates the bod} of the arm> worm and ulti- 
 mately destroys it, unless the caterpillar 
 should happen to casl its skin so soon after 
 the eggs are laid thai thej do uol have tunc 
 to hatch. The adull tachina-fl} resembles 
 a rather large house-fly, except that il has 
 B red tip to its abdomen. Hundreds and 
 thousands of these flies are usually seen 
 buzzing aboul a field infested 1>> the arm 3 worm, and theirpresence 
 should be welcome to the fanner. 
 
 The extenl of the parasitism of the injurious br I ol the armj 
 
 worm may be indicated b 3 two instances from our personal experience. 
 In 1880 we visited a large tract of land planted in timothy grass ... 
 the vicinitv of Portsmouth, Va. A search for hours during the hot 
 partoftheda^ failed to show a single worm which did not bear tachina 
 
 a i„ ,ss- xx,. visited wheat fields in the vicinity ol HuntsviUe, 
 
 S which were then being overrun b 3 this insect. Here, although a 
 Qum 'ber of worms were noticed which did nol bear tachina eggs, they 
 were destroyed b 3 ground-beetles to such an extent that when we 
 attempted to catch an adult moth a little later in the season b 3 means 
 of trap lanterns and sugar, we were unable to secure a single specimen. 
 The entire army had been amuhilated, and i1 is worthy ol remark tnal 
 1U neither of these localities has the army worm ever been seen since 
 m injurious numbers, although fourteen years have elapsed in the one 
 case and twelve in the other. 
 
 1.. ( >. lloxx \i:i>. 
 
 Entomologist. 
 
 Approved : 
 
 .1. Sterling M«>k roN, 
 
 Secrt tary. 
 
 \\ ilshinoton, l> C, •/'"" 16, 
 
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UNIVERSITY OF FLORIDA 
 
 3 1262 09216 5918