628 
THE STUDY OF INSECTS. 
middle of cross-vein III-VII (Fig. 755); but in Fcenus 
(Fce'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, 
-rK 
Fig. 757 .—Evania cippendigaster. Fig. 758.— Fcenus. 
Evanta 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 (Fce'nus) (Fig. 758), common on flowers. 
We have named these insects Ensign-flies, because they 
carry the abdomen aloft like a flag. 
Family CHALCIDIDiB (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. Fig. 760 .—Aphycus eruptor. 
tions, although some species are yellow. The head is 
usually large; the prothorax does not extend back on each 
