SERPHOID AND CHALCIDOID PARASITES OF THE HESSIAN FLY 67 



HOSTS AND LIFE HISTORY 



All except 1 of the 30 specimens of this species that have been seen 

 by the writer were reared from Phytophaga destructor. The one ex- 

 ception is a female said to have been reared, by T. R. Chamberlin, 

 from Harmolita sp. infesting the stems of canary grass at Gaston, 

 Oreg. 



According to Packard the parasite oviposits in the puparium of the 

 fly in the spring and summer. It is apparently a primary parasite 

 and probably feeds externally upon the host within its puparium. 

 Emergence takes place in the spring, a single parasite issuing from 

 each parasitized host puparium. 



DISTRIBUTION 



This species is apparently confined to the Pacific coast of the 

 United States. Packard states that its distribution is apparently 

 limited to the Salinas Valley in California, but one specimen in the 

 National Museum collection was reared from the hessian fly by M. 

 C. Lane at Chehalis, Wash., and, as already mentioned, another 

 specimen was reared from Harmolita sp. collected at Gaston, Oreg. 



IMPORTANCE 



According to Packard this species is the predominant parasite 

 of the fly in the Salinas Valley. Elsewhere it must be of very little 

 importance, if one may judge by the rarity with which it has been 

 sent in for identification. 



POLYSCELIS MODESTUS Gahan 



(Fig. 16) 



Polijscelis modestus Gahan, U.S. Natl. Mus. Proc. 61 (art. 24): 11, 1922; 

 Myers, Jour. Agr. Research 29 : 289, figs. 1 and 2, 1924 ; Hill and Smith, Jour. 

 Agr. Research 36 : 153, 155, 1928 ; Ent. Soc. Wash. Proc. 33 : 182, pi. 12, 1931. 



DESCRIPTION 



The combination of a 6-jointed funicle, 3- jointed club, an immar- 

 gined occiput, prominent neck on the propodeum, and the presence 

 of a subcircular but often rather faint cloud on the disk of the fore 

 wing in females of Polyscelis modestus distinguishes it from all other 

 species attacking the fly. Males may be recognized at once by the 

 fact that all the legs are pale yellow except the middle tibiae, which 

 are in large part black or dark brown. This peculiar combination 

 of leg markings occurs in no other species attacking the fly. 



The original description of the species was as follows : 



Female. — Length 2.2 mm. Head and thorax closely and strongly punctate ; 

 abdomen polished. Head transverse, a little more than three times as broad 

 as thick antero-posteriorly ; viewed from in front, slightly broader than long, 

 not or but slightly narrowed below, clypeal area with converging striae; malar 

 space equal to about half the eye height ; eyes ovate, without pubescence ; ocel- 

 locular and postocellar lines approximately equal ; occiput concave, transversely 

 reticulate, without any indication of a marginal carina ; antennae rather slen- 

 der, subclavate, with two ring joints, a 6-jointed funicle, and a 3-jointed 

 club ; first funicle joint and ring joint combined distinctly longer than the 

 pedicel ; all funicle joints a little longer than broad, the last nearly quadrate ; 

 club slightly longer than the two preceding funicle joints combined ; pronotum 



