THE LEGUME POD MOTH. 



93 



covered, measured 1.2 mm. in length and was found just inside the 

 pod at the terminus of a burrow which led from just in front of the 

 egg through the calyx and pod wall. The hole through which the 

 larva emerged from the eggshell was terminal, round, and very neatly 

 cut. A few days later two eggs were found on the calcyces of field 

 peas; these were brought into the insectary but failed to hatch. 



During late July and early August, 1911, larvae in all stages of 

 development, from very small specimens, evidently just hatched, to 

 those which were mature and spinning cocoons, were found in both 

 the pods of field peas and lupines. The larvae on first emerging are 

 pale green or cream colored, the pronotal plate and head being 

 entirely black or brown; with the first molt the pronotal plate assumes 

 the characteristic pattern described elsewhere in this paper, but the 

 body does not assume the rosy tint as described until nearly mature. 



The larvae feed for about three weeks, only partly consuming the 

 peas, as is seen in figure 32, destroying them as seed, besides greatly 

 reducing their weight as stock feed. The pod always contains a mass 

 of frass held to- 

 gether by a loosely 

 constructed web. 

 The larva will 

 leave one pod and 

 enter another if 



the food SUpply IS Fig. 32.— The legume pod moth: Larva feeding in a pod of field pea. En 



exhausted, or if large ' (0ngmal) 



for any other reason the pod becomes uninhabitable. When mature, 

 if the peas are still unharvested in the field, it emerges from the pods 

 and enters the ground to pupate, or if the pods have been harvested 

 it spins a tough silken cocoon in the nearest available sheltered place. 



Larvae that become mature during the warm weather of early 

 August, out of doors, or later under laboratory conditions, pupate 

 immediately and emerge as adults in about six weeks. Adults have 

 been obtained in our laboratory on August 5 and as late as August 28. 

 Whether these lay eggs which pass the winter successfully, or whether 

 they hibernate as adults, is still undetermined. Larva? that reach 

 maturity in late September, when the nights are cold, spin their 

 cocoons and hibernate therein as larvae, pupating in the spring and 

 emerging at the time the earliest lupines are setting seed. 



On the lupines there are very probably two generations a year. 

 The moths of the first generation, coming from hibernating larvae, 

 lay all their eggs on the lupines, as the field peas are just commencing 

 to grow. The offspring of this generation mature late in July and, 

 finding the field peas ripening, very naturally turn their attention 

 to these large areas of suitable food as well as to their natural food, 

 the later lupines. 



29993°— Bull. 95, pt. 6—12 2 



