4 Farmers’ Bulletin 1206. 
during the period from the time they issue from the egg until they are 
ready to transform into the pupa or resting stage. They feed all day 
_ long even during bright sunny weather, a ats not usual with other 
caterpillars. 
Although considerable damage is done by the caterpillars eating the 
foliage of vetch, the greatest injury is done to the pods, which they 
enter in search of seed (fig. 4). When grown with oats for a hay 
crop, vetch may escape serious injury, as generally it is cut before the 
caterpillars are of sufficient size to do serious damage. When 
vetch is intended for a seed crop, however, or when part of the crop 
is left for seed, injury may be much more severe; for by the time 
the seed pods are well developed the caterpillars are about full grown 
and require a large amount of food. During a serious infestation 
the damage to the crop may be so great as to render it practically 
worthless for seed. 
Pods which have been robbed of their seeds by the caterpillars 
often show no visible evidence of injury other than a small hole in 
the side made by the worm upon its entrance or exit. If such a pod 
be opened it will be found that all the seeds have been eaten. Some-: 
times, however, the sides of the pods are much damaged; in fact, 
often eaten half away. 
WHAT THE CORN EARWORM EATS. 
The corn earworm is practically omnivorous. Besides feeding on 
vetch, corn, cotton, tobacco, alfalfa, and tomatoes, it has a variety 
of food plants upon which it may subsist. Some of the, more impor- 
tant are beans, pumpkins, peanuts, squash, cowpeas, pepper, aspar- 
agus, and sunflower. The caterpillars have also a cannibalistic habit, 
which is especially noticeable when a number of the caterpillars are 
closely confined. In such instances there is a battle to death, the 
victors devouring their antagonists. These caterpillars also feed 
upon other soft-bodied insects and are known to feed upon both 
the caterpillars and the pupe of the alfalfa caterpillar, a most de- 
structive insect pest of alfalfa in the southwestern United States. 
WHEN A SERIOUS INFESTATION MAY BE EXPECTED. 
Cool, moist weather favors an outbreak of the corn earworm on 
vetch, not only because this kind of weather is favorable for the 
development of the insect but also because it is conducive to a lux- 
urious and dense growth of the vetch. Then, also, during such 
weather conditions the insect enemies of these caterpillars are hin- 
dered in their work. Cold weather has no apparent effect on the 
pup in regions where the insect is a pest of vetch because they are 
