THE LEGUME POD MAGGOT. 



(Pegomya planipalpis Stein.) 



By James A. Hyslop, 

 Agent and Expert. 



GENERAL ACCOUNT. 



About the middle of July, 1909, a large number of larvae of Pegomya 

 planipalpis Stein were found leaving the pods of lupines that had 

 been placed in rearing cages. On the 28th two pupae were found in 

 one of the cages. Within the next few days many more larvae left 

 the pods and pupated. A number of these puparia placed in a glass 

 vial during the autumn of ID 10 were kept in the field laboratory all 

 winter. May 11 of the following year the first adult emerged and 

 from that date others emerged daily throughout the remainder of 

 the month. By a number of experiments it was found that humidity 

 greatly facilitated the emergence of these flies. 



These flies were first believed to be scavengers, feeding on the 

 frass and decaying seed of the lupine and field peas in the wake of 

 the legume pod moth. However, investigations in 1910 proved that 

 the insect, though often found with Etiella, was quite capable of 

 independently infesting seed pods and was itself an actual seed de- 

 stroyer. Many pods were found to contain from one to three of these 

 larvae. 



Dr. F. H. Chittenden/ of this bureau, notes this species as attacking 

 radishes at San Francisco, Cal. 



The larvae molt at least twice, as two pairs of pharyngeal hooks 

 were found in a pod with one larva. Though several of these dipter- 

 ous larvae were found in field-pea pods with the head capsules of 

 larvae of the legume pod moth, we hardly believe this species to be 

 parasitic, as larvae confined in small vials with pod-moth larvae would 

 not attack the latter. 



In cages with earth in the bottom the pupae were always to be 

 found below the surface at distances ranging from 1 to 3 inches. The 

 larvae contract just before forming a puparium. The puparium is 

 at first creamy yellow, turning brown at the ends first and finally 

 becoming entirely ferruginous. A larva that contracted on the 

 morning of July 31, 1911, assumed the usual puparium form by 9.30 

 a. m. of the same day. It was still pale yellow, but by 2.30 p. m. it 

 had become brownish at the ends and deep orange-yellow at the 

 middle, while next morning the puparium was uniformly ferruginous, 

 brown. 



i Bui. 66, Pt. VII, Bur. Ent., U. S. Dept. Agr., p. 95, 1909. 



105 



