A New Parasite of the Hessian Fly

Stephen Alfred Forbes
1888 Psyche: A Journal of Entomology  
Parasitism of the winter brood of the Hessian fly has been but rarely and doubtfully reported, and so tar as I know, has not hitherto been strictly attthenticated. An observation recorded by Prof. Herrick in 84 1, probably referring to the parasite now known as Plalyffasler herrickii, Pack., implies an abundant development of that species in the hibernating generation of the fl" " but this observation was almost certainly incorrect in so,he respects,--as has been shown by Mr. Howard,--and has
more » ... t been verified in this particular. The breeding of unknown parasites from ifested wheat in spring was reported by the writer in 885 ;a but the breeding cage management in this case was not such as to make it certain that these were derived from the Hessian fly. The follo,ving instance is, consequently, probably the first to establish clearly the occurrence of this phenomenon. From a field of wheat sowed after oats and corn in the autumn of 886, living plants containing numerouspuparia of the Hessian fly were sent to me Mlr. 5, 887, by my correspondent Samuel Bartley, Esq., of Edgewood, insouthern Illinois. A number Herrick, C E. A brieI preliminary account of the hessian-fly and its parasites. (Amer. journ, sci. and arts, 84 4 , p. 53q55), p. 57. lmvard, L.O. (3d rept. U. S. entom, comm., 883, P. 9, foot note.) 3Forbes, S.A. (4th rept. State entom. Ill., p. 46, foot-note.) of these puparia were enclosed in a dry vial; and Dora them seven imagos of Cecidomyia destruclor emerged previous to the 3 d of April. This vial was not again examined until Oct. 8 when seven proctotrupid parasites were found in itall dead. These belonged to the genus tlatygaster as litnited by Foerster and Thomson, and to a species apparently undescribed. Plalygaster hiemalis, n. s. General surface smooth, shining black; head opaque, very slightly pubescent, not cuboid, wider than thorax, nearly twice as wide as long. Temples narrow, vertex not margined, but minutely transversely rugulose. Front also transversely corrugated above the antennae, this corrugation merging in a general irregular lineation of the face. Upper half of fi'ont regularly convex, lower with a slight vertical carina commencing between the bases of the antennae. Ocelli not elevated, lateral ones equidistant from the eye and the median ocellus. Thorax short, deep, very convex, not compressed; prothorax minutely transversely lineate at the sides; mesothorax shining, ovate, broadest just before wings, dorsum bare in middle, elsewhere with sparse gray hairs, sides more hairy in fi'ont. Parapsidal grooves scarcely visible. Scutellum semi-circular, vaulted, nearly hemispherical, without angle or process, 4Foerster, A. I-Iymenopterologlsche studien, heft 2, 8o, p. o8 and IXS. Thomson, C. G. Sveriges proctotruper. ((5?vers. af fjrhantl., 859, I6, P. 83.
doi:10.1155/1888/79108 fatcat:vdh65q57jbhphaey4sus7vmui4