ALFALFA CATERPILLAR 243 



of larvae upon any of the crucifers available. Early cab- 

 bages may be attacked, the larvse feeding simply on the 

 leaves. Eggs are commonly deposited on wild mustard, etc., 

 anfl the larvie develop on these plants. The pupal stage for 

 the first brood is quite short, about two weeks to twelve 

 days. There is enough variation in the time of appearance, 

 so that the butterflies may be present for three or four weeks 

 in both spring and summer, and so they are to be found 

 pretty well through the summer months up to the middle of 

 August or the first of September. The great bulk of them 

 come at about the time vegetation is opening up and again 

 about the first of August. The species is not very easily 

 controlled. It lives on a variety of food plants and is two- 

 brooded and this helps in sustaining it. If the first brood 

 could be destroyed it might be controlled, but it is hard to 

 do this. Trap crops may be planted, as mustard, etc., 

 and then the entire crop destroyed after the eggs are deposited 

 on it. Butterflies can be captured while depositing eggs, a 

 cheaper method than applying insecticide. Remedies can 

 be applied to the cabbages, especially before they have 

 headed without any danger to the eating of the cabbages 

 after they have grown. It should be done with precaution, 

 especially after the cabbages have reached some size. If the 

 solution is the right strength, there is practically no danger, 

 as twenty-eight cabbages would have to be eaten at one meal 

 to poison a person. The best way is to apply poison before 

 the cabbages are headed out. If the treatment is pretty 

 thorough for the first brood and the early part of the second, 

 the effect will be pretty successful. Gathering of the pupa; 

 is possible, but is not practicable on a large scale. It is 

 better not to destroy these, but to pass them into a receptacle 

 with a wire screen so that the parasites may escape while 

 the butterflies do not. The parasites are sometimes abun- 

 dant and greatly reduce the numbers and in some seasons 

 render the use of remedies unnecessary. 



Alfalfa Caterpillar {Eurymus eiiryihcme) .- — The alfalfa 

 caterpillar is a common species over most of the United 

 States and has attracted attention as a serious pest in the 



