INSECTS AFFECTING GRAINS, GRASSES, FORAGE 117 



which gives the specific name unipuncta. The hind-wings are 

 somewhat lighter with blackish veins and darker margins. 



Enemies. Were it not for other insects which prey upon the 

 army worm, the army habit would doubtless be more often 

 assumed and we should have to deal with them more frequently. 

 Ordinarily, however, the parasitic and predaceous insects hold 

 them in check very efficiently and when an outbreak does occur, 

 the later broods of the same season are often entirely destroyed by 

 their insect enemies. Large numbers are always destroyed by the 



FIG. 87. The farmer's friend, the red-tailed tachina-fly (Winthemia -pustu- 

 lata): a, natural size; b, much enlarged; c, army worm on which fly 

 has laid eggs, natural size; d, same, much enlarged. (After Slingerland.) 



predaceous ground-beetles and their larvsB (p. 14), but their 

 most deadly enemies are the tachina-flies (p. 106). These lay 

 from a dozen to fifty eggs on a caterpillar, and the maggots 

 from them enter the body and absorb the juices and tissues of 

 the host, thus soon killing it. When feeding at night the worms 

 are ordinarily free from these parasites, but when the marching 

 habit is assumed the flies swarm around them on cloudy days 

 and before the next year they again have the remnants of the 

 voracious army under subjection. Therefore, worms with the 



