True Army Worm 



NATURE OF INJURY 



In the case of leaf-eating insects the damage done is usually pro- 

 portionate to the amount of leaf surface destroyed. However, the true 

 army worm is an exception to this rule. When feeding, these worms 

 have the habit of climbing grass and grain stalks and gnawing off the heads. 

 When grain is in the shock, especially if harvested a little green, the heads 

 are often gnawed off also. For this reason the damage greatly exceeds 

 that of most insects of this class in that the army worm destroys much 

 more than it actually eats. 



Sugar beets are seldom damaged except where they lie in the path of 

 the moving worms or next to infested small grain or grass crops. When 

 attacking this crop the worms overrun the leaves, at the same time eating 

 irregular areas out of their margins. In case of severe injury all of the 

 leaves with the exception of the coarse stems may be destroyed. The 

 roots are seldom, if ever, eaten. The army worm usually appears so late 

 in the season that few beets are killed. 



METHODS OF CONTROL 

 Spraying 



When the nature of the crop attacked is such that poison can be 

 applied in the form of a spray, without danger of poisoning either live 

 stock or human beings that use the crop as a food, the army worm can be 

 effectively controlled by spraying with Paris green or lead arsenate. 

 The same proportions of poison and water should be used as in the control 

 of the beet webworm ; i. e., 4 pounds of Paris green or 16 pounds of arsenate 

 of lead paste to the amount of water used in spraying an acre. Remem- 

 ber that the sprayer should be adjusted so as not to apply more than 100 

 to 125 gallons per acre. 



Poisoned Bait 



When the food supply has become exhausted and the worms have 

 started across country in search of new pasturage, the poisoned bait 

 recommended in the control of cutworms will prove most effective. (See 

 pages 39 and 40.) This should be scattered in the path of the worms. 

 Several strips of a rod or so wide with about the same distance between 

 them will give the best results. As the worms are most active during 

 the latter part of the afternoon this is the best time to put out the bait ; 

 however, if the army is on the move earlier, the poison should be scattered 

 earlier. 



Furrow Trap 



This consists of a furrow plowed across the path of the advancing 

 worms. The soil should be thrown toward the worms so as to leave the 

 perpendicular side of the furrow opposite them. Post holes should be 

 bored in the bottom of the furrow every few feet. As the worms enter 

 the furrow they will attempt to climb up the perpendicular side. Many 

 failing in this will wander up and down the furrow in search of a place 

 where they can climb out. In this way many will fall into the post holes. 

 The worms thus trapped can be killed by crushing them with a piece of 

 wood or by pouring a small quantity of kerosene into each hole. Some- 

 times the post holes are not used. In their stead a small log or heavy 



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