SEEPHOID AND CHALCIDOID PARASITES OF THE HESSIAN ELY 7 



fovea on each side at base and with the surface within and around these foveae 

 distinctly though not deeply aciculated; tergites beyond the second short, 

 smooth, and each with a few pale hairs. 



Color of body usually deep shining black but sometimes brownish black; 

 antennae brownish black, the extreme base of scape narrowly and more or less 

 of the third segment testaceous; legs brownish black, the trochanters, knees, 

 and apices of all tibiae usually very slightly testaceous, all tibiae testaceous 

 with the apical joint dark. Wings hyaline. 



Male. — Length 0.75 to 1.3 mm. Fourth joint of the antennae much enlarged, 

 larger than the pedicel and more than twice as long as the small third joint, 

 curved, its dorsal margin convex, its ventral margin concave ; fifth to ninth 

 segments subequal. In other respects like the female. 



Described from many specimens in the United States National 

 Museum. 



REVIEW OF LITERATURE 



The name Platygaster Memalis was first proposed by S. A. Forbes 

 in 1888. The record, by E. C. Herrick in 1841, of Platygaster sp. 

 attacking the hessian fly in autumn by inserting 4 or 5 eggs in 

 a single egg of the host, and of their emerging as adults from the 

 puparium of the fly, can only apply to Memalis and is the first refer- 

 ence in literature to this species, as was correctly pointed out by C. C. 

 Hill in 1922. Herrick's account of the oviposition and develop- 

 ment of this insect was likewise the first record of such a mode of de- 

 velopment in any parasitic hymenopteron, a fact that has apparently 

 been generally overlooked or ignored in recent years. A. S. Packard, 

 in his treatise on the hessian fly published in the third report of the 

 United States Entomological Commission, expressed doubt as to 

 Herrick's statement and L. O. Howard, in a footnote attached to the 

 same article (p. 219), also declared that in his opinion the correctness 

 of Herrick's observation was in the highest degree improbable. C. 

 V. Eiley in 1885 likewise stated his belief that Herrick's observations 

 were erroneous. Subsequent investigations by others have shown 

 that not only this species but also many others develop in the man- 

 ner described by Herrick, and to him should go the credit for a 

 discovery which has largely been credited to others. 



Herrick's observations were several times reviewed and com- 

 mented upon by Fitch and also by Harris, and in 1866 Fitch proposed 

 the name Platygaster herrickii for the species discussed by Herrick. 

 Unfortunately, however, he did not validate the name by a descrip- 

 tion of the adult. Subsequently, in 1880, Packard published a de- 

 scription of a parasite of the fly which he identified doubtfully as 

 P. error Fitch but stated that if it should prove to be a different 

 species it might be called Platygaster herrickii. He supposed this 

 to be the same species as that dealt with b}^ Herrick. Riley pointed 

 out that the insect described by Packard was probably different from 

 P. errw Fitch and adopted the name P. herrickii for it, as Packard 

 had suggested. Packard's species is now well known under the name 

 mentioned and is discussed elsewhere in this paper. Its life history 

 is very different from that of the insect observed by Herrick, all of 

 whose observations agree exactly with the now known life history 

 of Memalis Forbes. 



Platygaster minutus Lindeman was described as a parasite of the 

 hessian fly in Russia in 1887. Lindeman stated that he had taken 

 this parasite from puparia of the fly collected at Moscow, in the 



