70 



THE ARMY WORM 



THE ARMY WORM S ENEMIES 



Fortunately for the American farmer, the army worm has a 

 host of natural enemies, which generally keep it below the dan- 

 ger line. A large number of birds consider the juicy worms 

 excellent eating, and feed freely upon them. A list of such 

 birds would include nearly all our native insectivorous species 

 that search for food upon the ground, but special mention 

 should be made of the robin, the blackbird, the bobolink, and 

 the meadow lark, which search grass-lands for insect larvjE 

 more persistently than many other of our common birds. 

 These and other birds are very useful in keeping army worms 

 and cutworms in check, and should be encouraged by every one. 

 But the birds are not the only enemies of the army worm. 

 In the fields where the pest has been present this season there 

 have also been found a great many large black beetles, some of 

 them similar to the one represented in Fig. 7^ and others some- 

 what larger. During July I examined a barley field in which 

 the grain had recently been cut and placed 

 in piles, beneath which the army worms had 

 congregated in great numbers. There were 

 also present beneath each pile about a dozen 

 of these black beetles, devouring the helpless 

 worms. These predaceous beetles are com- 

 monly called ground beetles, because of their 

 habit of living upon the ground, but some- 

 times they are also called caterpillar hunters. 



^ ^, , ^ J There are also many species of internal 



Fig. 7. Black Ground -^ ' 



Beetle. (After Riley). P^''^sites that prey upon the army worms. 

 Among the most abundant of these are cer- 

 tain two-winged flies that glue eggs upon the backs of the 

 worms. The eggs hatch into tiny footless maggots, that enter 

 the bodies of the worms when they hatch, and develop inside 

 at the expense of their unwilling hosts. Finally they kill the 

 worms and the maggots change to pupcE, from which they soon 

 emerge as flies. These are called Tachina flies. 



There are several species of four-winged Ichneumon flies 

 tliat have a similar history, and are often very destructive to 

 the hosts of army worms. 



