i 



REPORT OF THE STATE ENTOMOLOGIST I905 65 



old. There is considerable difference in the rate of development, 

 which is caused largely by the abundance and condition of the 

 food. 



Indications of injury. The signs of this insect's presence are 

 not very striking till serious damage has been inflicted. Oats for 

 example appear to be abnormally thinner and on examination it 

 may be found that most of the leaves have been eaten away. An 

 unusually early ripening should arouse suspicion. The character- 

 istic black droppings on the surface of the ground should lead to 

 scrutiny. Light patches in the field should be examined for signs 

 of this insect's work, and a search under stalks, stones or any adja- 

 cent shelter may result in exposing the caterpillars. 



Natural enemies. This pest has a large number of natural ene- 

 mies, which are undoubtedly very serviceable in controlling this 

 species. Unfavorable weather conditions destroy many of the 

 hibernating insects and at times a deadly bacterial disease cuts off 

 thousands of caterpillars. Vertebrate enemies such as swine, 

 shrews, skunks, weasels, domestic fowls, specially ducks and geese 

 and various insectivorous birds devour large numbers of the cater- 

 pillars whenever they are numerous. Predaceous insects such as 

 the ground beetles and the tiger beetles also aid in the good work, 

 one of the most efficient of the former being the fiery ground beetle, 

 Calosoma calidum Fabr. 



Native parasites play an exceedingly important part in checking 

 this species. The red-tailed Tachinid Winthemia quadri- 

 pustulata Fabr., sometimes occurs in swarms in an infested field, 

 and its rather large, whitish eggs are frequently observed just be- 

 hind the head of unfortunate caterpillars. An almost equally abun- 

 dant and efficient enemy is found in the closely allied yellow-tailed 

 Tachina fly, Belvoisia unifasciata Desv. A number of 

 allied species assist in this work and their efforts are supplemented 

 by those of several minute four winged flies, one of the best known 

 of these latter being the so called military microgaster, A p a n - 

 teles militaris Walsh. The rather large, reddish, flattened, 

 wasplike parasite, Eniscopilus purgatus Say, is another 

 valuable check upon this species. 



Preventive and remedial measures. The most important thing 

 to be borne in mind in connection with this insect is that the moths 

 deposit their eggs by preference on coarse vegetation of one kind 

 or another and as a result army worm outbreaks are likely to occur 

 in the vicinity of rank weed growths such as neglected spots about 



I 



