120 MISC. PUBLICATION" 17 4, U.S. DEPT. OP AGEICULTURE 



closely allied to the genotype species. Between smaragdina and 

 aeneus there is essentially no difference in the relative proportions 

 of the marginal and stigmal veins. Furthermore, the males of both 

 species have the two distal joints of the maxillary palpi almost 

 equally greatly enlarged. It follows, therefore, that Dicydus and 

 Halticoptera cannot be distinguished generically by either the vena- 

 tion or the characters of the male palpi, and apparently there are no 

 other characters of sufficient importance to hold them apart. In 

 H. smaragdina there is in both sexes a more or less distinct cross 

 furrow on the scutellum at about the apical one third. In males of 

 this species also, the basal lobe or stipes of maxilla is enormously en- 

 larged, so much so that it appears as a very large, flat, smooth plate 

 lying close against the back of the head and extending nearly to the 

 vertex, where it is easily seen from above if the head is tipped 

 slightly forward to expose the occiput. It was at first believed that 

 these characters would distinguish Halticoptera from Dicydus, but 

 further study showed them to be merely relative. In many speci- 

 mens of aeneus the cross furrow on the scutellum is absent, but in 

 some specimens it is faintly indicated, although never so distinct as 

 in the few specimens of smaragdina available for comparison. The 

 stipes of the male maxilla in aeneus is not so enormously enlarged 

 as in smaragdina, never extending above the neck and hence not 

 visible from above, but it is much larger than usual in other Ptero- 

 malidae and essentially of the same type as in the latter species. In 

 the light of this comparison it is deemed necessary to consider Dicy- 

 dus a synonym of Halticoptera. 



Ashmead described the species three times in Cyrtogaster and 

 once in Polycyrtus (a typographical error for Polycystus) and 

 Crawford also placed it in Polycystus. 



It has little relation to Cyrtogaster. Females of Cyrtogaster are 

 at once distinguished from those of Halticoptera by having a broad, 

 almost semicircular emargination of the first tergite, by the sharply 

 margined pronotum, and by the rugosely sculptured propodeum, 

 while the males differ not only by these same characters but in the 

 maxillary palpi also, since in Cyrtogaster it is apparently the 

 penultimate palpal joint which is enlarged, and this is always me- 

 tallic, 2 the apical joint small and either club shaped {vulgaris 

 Walker) or setiform (glasgotvi Crawford) and located near the 

 forward or ventral end of the penultimate joint when the palpi are 

 at rest. 



The true identity of Polycystus Westwood, of which P. matthewsii 

 Westwood is the genotype species, is at present unknown to the 

 writer. 



HOSTS AND LIFE HISTORY 



Halticoptera aenea is a solitary, primary parasite with a number 

 of different hosts. According to Imms, it is an endoparasite of 

 the larval stage of Oscinella frit emerging as an adult from the 

 puparium of the host. Little else is known of its life history. 



Oscinella frit is attacked by this species in both Europe and 

 America. Cunliffe, as well as Imms, records it from that host in 

 England. In North America the records by Ashmead and Webster 

 of its having been reared from Oscinis carbonaria Loew, O. varia- 

 bilis Loew, O. soror Macquart, or 0. umbrosa Loew have been shown 



