128 HYMENOPTERA. 



lustre. The wings have few veins, in some species they 

 are absent. In some genera the femur of the hind-legs 

 is enormously swollen, and sometimes internally ser- 

 rated ; this thickening does not, however, as we might 

 be inclined to think, indicate leaping powers. These 

 insects are all parasitic upon others, cliietly in their 

 larva and pupa states ; some lay their eggs even w^ithin 

 the eggs of other insects, and the larvae are nourished 

 therein, which may give us some idea of their minute 

 size. 



The Proctotrupidw, like the preceding fiimily, con- 

 tains insects of very small size. A species of Platy- 

 gaster is useful in checking the injury done to wheat 

 by the two-winged insect, the Cecidomyia triticL 

 There are about four hundred British species in this 

 family. 



We now come to the division of the Tuhullferw, so 

 called from the structure of the abdomen, the end of 

 which is retractile like a telescope. The Ruby-tails 

 iChrijsidw) alone constitute this family, of w^hich the 

 common Chrysis ignita (Plate V., Fig. 6) is a good 

 representative. The brilliant colouring of this insect, 

 with its head and thorax of metallic blue or green, and 

 abdomen of crimson or fiery copper, has won it the 

 name of the humming bird amongst insects. The 

 Chrysis is parasitic in its habits, depositing its eggs 

 within the cells of other Hymenopterous insects. The 

 subject of the parasitism of the Chrysides has recently 

 been investigated by Dr. Chapman (of Borghill, 

 Hereford), who in conjunction with Mr. Steele of 

 Abergaveny, has published in the transactions of the 

 Woolhope Naturalists' Field Club, some very valuable 



