628 



THE STUDY OF INSECTS. 



middle of cross-vein III-VII (Fig. 755); but in Fcenus 

 (Foe'nus) (Fig. 756) vein V has migrated so far toward the 

 anal furrow that it no longer arises from the cross vein, and 

 cell V is reduced to a mere areolet. 



These insects are parasitic ; we have bred one species, 



Fig. 757 — Evania appendigaster. 



Fig. 758.— Fcenus. 



Evania appendigaster (E-van'i-a ap-pen-di-gas'ter) (Fig. 757), 

 from the ootheca of a cockroach, and have found another, 

 a species of Fcenus (Foe'nus) (Fig. 758), common on flowers. 

 We have named these insects Ensign-flies, because they 

 carry the abdomen aloft like a flag. 



Family Chalcidid^e (Chal-cid'i-dae). 

 The Chalcis-flies. 

 The Chalcis-flies are among the smaller of the parasitic 

 Hymenoptera. In fact they are usually minute insects, 

 often not more than one one-hundredth of an inch in length ; 

 on the other hand, a few of our species are much larger, a 

 common one measuring three eighths of an inch in length. 

 They are nearly always black, with strong metallic reflec- 



Fig. 759.— Dilophogaster californica. FlG. 760. — Aphycus emptor. 



tions, although some species are yellow. The head is 

 usually large ; the prothorax does not extend back on each 



