HYMENOPTERA 



030 



and branches of the CaHfomia white oaks, and during the winter, 

 when the trees are bare, it is a very conspicuous object, on account 

 of its abundance and large size. It varies in shape from globose to 

 reniform and also varies greatly in size; some of the larger ones 

 measure more than loo mm. in their greatest diameter. The outer 

 surface of the gall is white and usually smooth; the interior is more 

 or less filled with a compact soft material, and contains from one to 

 a dozen larval cells. Several varieties of the gall-fly that produces 

 this gall are described by Kinsey ('22). 



The mossy rose-gall, RJwdltes roses. — This is a very common poly- 

 thalamous gall, which is fonned on the stems of rose bushes, especially 

 of the sweetbrier. The gall consists of a large mass of moss-like 

 filaments surrounding a cluster of hard kernels (Fig. 11 64). In each 

 of these kernels a gall-fly is developed. The galls appear early in the 

 summer, but the adults do not emerge till the following spring. These 

 are male and female; there is no alternation of generations in this 

 species. 



SuPERFAMiLY CHALCIDOIDEA 



The Chalcid-flies 



This superfamily is the most 

 highly evolved of the Hymenop- 

 tera. It includes the family Chal- 

 cididse with a very large number 

 of genera and species. A few 

 species are as large as honey-bees, 

 but the vast majority are minute. 

 Most are black or metallic green- 

 ish in color, but some are brown 

 or yellow. The most distinctive 

 feature of the group is the pres- 

 ence of a separate sclerite, the 

 prepectus, in front of the meso- 

 pleurum. This sclerite is inter- 

 posed between the pronotum and the tegula so that the two are not 



in contact as in most other Hy- 

 menoptera. In a few chalcids the 

 prepectus is very small or entirely 

 absent. Chalcids have the an- 

 tenna elbowed and never with 

 more than thirteen segments. 

 The ovipositor usually does not 

 extend beyond the tip of the ab- 

 domen but may be quite long. 

 Each wing has only a single vein. 

 In some genera a few other indistinct veins can be traced. 



Fig. 1 165. — A chalcid-fly, Aphycus 

 emptor. 



Fore wing of a chalcid-fly, 



