•14 



THE MONTHLY BULLETIN. 



alfalfa plant. I have seen as manj^ as fifty small larvfe on one leaf and 

 several hundred on the entire plant. As they become larger they will 

 scatter to adjoining plants, eating the leaves as they go. Fig. 382 

 shows a larva of Mamestra picta destroying the leaf tissues of the alfalfa. 

 Often at a radius of several feet from the originalh^ infested plant the 

 larvre may be found working on the leaves. 



Fig. 382. — Larva Mamestra picta on an 

 alfalfa leaf. (Photo by Reeves.) 



An interesting note in connection with the feeding habits of this 

 caterpillar was observed in an alfalfa field at Salt Lake, Utah. Dur- 

 ing the latter part of September and the first of October. Avhen the 

 alfalfa leaves were becoming too tough, the larvaa would migrate to the 

 edges of the field and feed on the tender growth of dock, which was 

 very abundant along the ditch banks. Day after day the larvfB were 

 picked off the dock, and each time a new number of well grown larvje 

 appeared. 



From September to October the caterpillars on becoming full grown 

 enter the soil to pupate. In the breeding cages a majority passed the 

 resting stage at a depth of from 4 to 6 inches. The winter is passed 

 in this stage, the moths appearing in the spring. There are probably 

 several generations, but the last generation in the fall is the one in 

 which the larvae are numerous enough to attract attention. 



At present the best method for the control of this pest on alfalfa is 

 to go through a field picking and destroying infested tops, which are 

 conspicuous because of their whitish color, when the larva? are in the 

 young stages and consequently massed on one or two stalks. If the 

 fields are pastured at this time of the year very little damage will result 

 from this insect's attack. 



Fig. 383. — Cocoon of Campoplex sp. 

 on alfalfa stem with the larval re- 

 mains of Mamestra picta. (Photo by 

 Reeves.) 



We have records of this insect occurring in the Atlantic States, Colo- 

 rado. Utah and California. 



Besides alfalfa, it attacks cabbage, celery, beets and other garden 



vegetables. 



