51 



in the season the moths prefer to oviposit in the cut straw of old stacks, 

 in haystacks, and even in old fodder stacks of corn, or in old bits of corn- 

 stalks scattered about in pastures." Eggs have also been found in the 

 spring in young grain. Slingerland reports that as many as 737 eggs 

 have been found in the body of a single moth — a fact which goes far to 

 account for the tremendous power of reproduction exhibited by this insect. 



Until after the second molt the young caterpillars have the looping 

 habit of the measuring- worms, and spin down at the end of a thread 

 when disturbed, as do the canker-worms. They often leave their feed- 

 ing grounds when they are scarcely more than half grown. They may 

 travel at the rate of five to ten rods an hour. 



Prevention and Remedy. — The fact that two successive generations 

 of the army- worm are never injurious in the same locality is due to the 

 sudden check placed upon their multiplication by a concentration and 

 increase of their enemies of various kinds, the most important of which are 

 insect parasites and parasitic diseases. Birds and ground-squirrels gather 

 for their destruction, but these larger animal enemies are rarely numerous 

 enough to produce any very marked effect upon the traveling horde. 

 Their insect parasites and fungous diseases, on the other hand, presently 

 come to affect them so generally that they perish wholesale either before 

 or after entering the ground for pupation, the soil in such cases stinking 

 with their decayed remains. Parasitic insects have been seen to swarm 

 about them in such numbers that the sound of their flight was like that of 

 a hive of bees. 



In case by watchfulness and good luck a farmer detects a colony of 

 army- worms before it has left its native field of grass or grain, he may 

 to advantage surround it by a few deep furrows so plowed that the dirt 

 shall be thrown inward towards the colony, and then either kill the 

 caterpillars as they collect in this furrow in their efforts to escape, or 

 poison them in a body by spraying the vegetation on which they feed 

 with an arsenical poison, like Paris green. 



To stop them and destroy them after they have taken up their line 

 of march, deep furrows are plowed in front of them. The straight side 

 of each furrow, which should be the side away from the worms, is trimmed, 

 if necessary, with a spade so that the dirt shall be perpendicular or 

 overhang a little, and post-holes are made in the bottom at intervals of 

 ten or fifteen feet where the caterpillars may collect in c{uantity as they 

 travel up and down the furrow seeking to escape. Here they may be 

 readily killed by pouring a little kerosene upon the struggling mass in 

 each post-hole, after which they should be shoveled out to make room 

 for another collection. 



Prompt and vigorous action is essential to success, since the pres- 

 ence of these insects is often not detected until they are well under way, 

 and their rate of movement is such that acres of corn may be sacrificed 

 by a few hours' delay. 



