INJURIOUS AND BENEFICIAL INSECTS OP CALIFORNIA. 



459 



Life History.— The insect hibernates in the adult and pupal stages, 

 the adults beginning to emerge early in the spring, about the first of 

 March. They immediately begin egg-laying in the alfalfa fields. The 

 caterpillars become very numerous and destructive during the summer 

 months. This was especially true during the year 1913, when thou- 

 sands of the butterflies hovered over nearly every acre of alfalfa from 

 Imperial to Modoc counties. In the San Joaquin Valley they appeared 

 especially destructive. Hay fields suffered most, but pastured fields 

 were seriously injured. There are two generations in the colder regions 

 and six or more in the warmer southern sections, according to Wilder- 

 muth. 



Nature of Work. — The larvae strip the leaves from the plants, 

 leaving only bare stalks. 



Distribution.— This butterfly occurs throughout the entire State. 



Fig. 470. — Adults of the alfalfa caterpillar, Eur inn as 

 eurytheme (Boisd. ). Enlarged one and one fourth times. 

 (Original) 



Food Plants. — Alfalfa appears to be a favorite host of this butterfly, 

 but many other plants are attacked, some of which are the following: 

 Trifolium reflexum, T. stoloniferum, white clover (T. rt pens), T. tridt n 

 tatum, Lotus sp., loco-weeds (Astragalus caryocwpus and A. crota- 

 larice), sweet clover (Melilotus alba), soja bean, peas and vetch. 



Control. — To successfully control such a pesl one tnusl resort to 

 a number of practices, all of which judiciously combined will give very 

 good results. The alfalfa should be cut, as soon as the larvae begin to 



