256 Bulletin 133. 



sustenance in a single army-worm. Sometimes these little 

 parasites are so numerous as to be of much help in checking the 

 pest. Some of the large ichneumon flies also attack the army- 

 worm.* 



Last year, in some parts of the state, thousands of the army- 

 worms and many more of their pupae were killed by a bacterial 

 disease, sort of an insect cholera ; the interior of worms and pupae 

 affected with this disease appeared rotten. 



How TO Fight the Army-worm. 



As army-worms are not easily and not often discovered in the 

 comparatively limited area in which a whole army of them may 

 breed, a farmer's crop of many acres may be thoroughly infested 

 with a ravenous army before he is aware of it. Where the worms 

 have thus taken possession of a field, but little can be done to 

 destroy them which will not also involve the destruction of the 

 crop. If the surface of the soil were smooth and hard enough, 

 the drawing of a heavy roller over the field would crush many 

 of the worms, but this " roller process " is not often nearly so 

 effectual as it would seem to be theoretically. A flock of 

 poultry turned into the field would lessen the numbers of the 

 worms somewhat. 



However, the worms can be prevented from entering other 

 fields, and may, in many cases, be checked and killed even after 

 they have entered a new field ; in some cases, especially in corn 

 fields, an advancing army may be stopped in the middle of the 

 field and thus half of the crop saved. The simplest and most 

 effectual method of doing this is to either dig a smooth-walled 

 ditch, or plow several deep parallel furrows in front of the 

 invading army ; the perpendicular, smooth side of the plowed 

 furrow should be towards the field to be protected. The worms 

 not being readily able to scale the perpendicular wall of the 

 ditch or furrow will drop back and begin crawling along the bot- 

 tom seeking an easier place of ascent. If deep holes have been 

 dug in the ditch or furrow at intervals of a few feet, the worms, 



* We bred several specimens of I\Teteorus hyphantriae Riley from army- 

 worms. This insect and its curious suspended cocoons were illustrated on 

 plate IV, a, b, r, of bulletin 123. 



