THE AMERICAN ENTOMOLOGIST. 



171 



numerous they retain this their normal 

 Cut-Worm habit, and only when they be- 

 come excessively multiplied do they ac- 

 quire the marching and migrating habits. 



REMEDIES. 



Experience has established the fact 

 that burning over a meadow, or prairie, or 

 field of stubble, either in winter or spring, 

 usually prevents the worms from originat- 

 ing in such meadow or field. Such burning 

 destroys the previous year's stalks and 



[Fig. 75.] 



Army Worm Morn; — a, end of abdomen denuded and 

 showing ovipositor at rest ; fi, same with ovipositor fully ex- 

 tended ; ?, /, retractile subjoints ; /f, eggs — all enlarged; ^', 

 eggs, natural size (after Riley). 



blades and, as a consequence of what we 

 have already stated, the nidi which the 

 female moth prefers. Burning as a pre- 

 ventive, however, loses much of its prac- 

 tical importance unless it is pursued annu- 

 ally, because of the irregularity in the 

 appearance of the Worm in injurious num- 

 bers. Judicious ditching,/.,?, a ditch with 

 the side toward the field to be protected 

 perpendicular or sloping under, will pro- 

 tect a field from invasion from some other 

 infested region when the worms are march- 

 ing. When they are collected in the ditch 

 they may be destroyed either by covering 

 them up with earth that is pressed upon 

 them, by burning straw over them or by 

 pouring a little coal oil in the ditch. A 

 single plow furrow, six or eight inches 

 deep and kept friable by dragging brush 

 in it, has also been known to head them 

 off. 



From experiments which we have made 



we are satisfied that where fence-lumber 

 can be easily obtained it may be used to 

 advantage as a substitute for the ditch or 

 trench, by being secured on edge and then 

 smeared with kerosene or coal tar, the 

 latter being more particularly useful along 

 the upper edge. By means of laths and a 

 few nails the boards may be so secured 

 that they will slightly slope away from the 

 field to be protected. Such a barrier will 

 prove effectual where the worms are not 

 too persistent or numerous. Where they 

 are excessively abundant they will need to 

 be watched and occasionally dosed with 

 kerosene to prevent their piling up even 

 with the top of the board and thus bridg- 

 ing the barrier. The lumber is not injured 

 for other purposes subsequently. 



SUMMARY. 



We conclude with the following summary 



of the natural history of the Worm as given 



in the 9th Mo. report above referred to ; 



"The insect is with us every year. Inordinary 

 seasons, when it is not excessively numerous, it 

 is seldom noticed : ist, because the moths are 

 low, swift flyers, and nocturnal in habit ; 2nd, 

 because the worms, when young, have protective 

 coloring, and, when mature, hide during the day 

 at the base of grasses. In \ears of great abun- 

 dance the worms are generally unnoticed during 

 early life, and attract attention only when, from 

 crowding too much on each other, or from having 

 exhausted the food supplj' in the fields in which 

 they hatched, they are forced, from necessity, to 

 migrate to fresh pastures in great bodies. The 

 earliest attain full growth and commence to travel 

 in armies, to devastate our fields, and to attract 

 attention, about the time that winter wlieat is in 

 the milk — this period being two months later in 

 Maine than in Southern Missouri ; and they soon 

 afterwards descend into the ground, and thus 

 suddenly disappear, to issue again two or three 

 weeks later as moths. In the latitude of St. 

 Louis the bulk of these moths lay eggs, from 

 which are produced a second generation of worms, 

 which become moths again late in July or early 

 in August. Exceptionally a third generation of 

 worms may be produced from these. Further 

 north there is but one generation annually. The 

 moths hibernate, and oviposit soon after vegeta- 

 tion starts in spring. The chrysalides may also 

 hibernate, and probably do so to a large extent 

 in the more northern States. The eggs are in- 

 serted between the sheath and stalk, or secreted 

 in the folds of a blade ; and mature and peren- 

 nial grasses are preferred for this purpose. The 

 worms abound in wet springs preceded by one 

 or more very dry years. They are preyed upon 

 by numerous enemies, which so effectually check 

 their increase, whenever they unusually abound, 

 that the second brood, when it occurs, is seldom 

 noticed ; and two great Army Worm years have 

 never followed each other, and are not likely to 

 do so." 



