EXTERMINATING NOXIOUS INSECTS. 279 



ger and from their sensibility to the sun's rays, to leave 

 the denuded field. When they have become nearly full- 

 grown, and have stripped bare the fields in which they 

 were born, and commence to march, they necessarily at- 

 tract attention; for they are then exceedingly voracious, 

 devouring more during the last three or four days of their 

 worm-life than they had done during the whole of their 

 previous existence. As soon as they are full-grown, they 

 burrow into the earth, and, of course, are never seen again 

 as worms. 



Their increase and decrease is dependent on even more 

 potent influences than those of a climatic nature. The 

 worms are attacked by at least eight different parasites ; 

 and when we understand how persistent these last are, and 

 how thoroughly they accomplish their murderous work, we 

 cease to wonder at the almost total annihilation of the 

 Army -worm the year following its appearance in such 

 hosts. In the words of the late J. Kirkpatrick, "Their 

 undue increase but combines the assaults of their enemies, 

 and thus brings them within bounds again." We must 

 also bear in mind that, besides these parasitic insects, there 

 are some cannibal insects, such as the Fiery Ground -bee tie, 

 which come in for their share of this dainty food ; while 

 the worms, when hard pushed, will even devour each other. 

 It is stated that Army-worm Moths do sometimes lay their 

 eggs before harvest upon growing grain, sufficiently high 

 from the ground for the egg to be carried off with the 

 straw, which accounts for several well - authenticated in- 

 stances of the Army-worm starting from stack-yards. 



The Army-worm larva varies but little in appearance 

 from the time it hatches to the time when it is full-grown. 

 Some specimens are a shade darker than others, but the 

 markings are generally uniform, as shown by Fig. 112, on 

 the following page, which represents an Army-worm of full 



