250 ANNULATA 
infest turnips. Many of the Aymenopiera have a sting at 
the hind end of the abdomen. ‘This is modified from the 
ovipositor which in its turn is comparable with the gonapo- 
physes of the cockroach. In the saw-flies the ovipositor is 
in the form of a pair of saws which are used for perforating 
holes in twigs, in which the eggs are deposited. 
OrvDER ILI.—Dzipeera. 
Fig. 169.—TsETSE FLY (Glossina morsttans) X 3. 
The deadly African fly. 
The Dipéera have a full metamorphosis, the mouth parts 
adapted for “ piercing and sucking,” and there is a single 
pair of membranous wings. . The hind wings are reduced 
to a pair of small Aalteres or balancers, processes with 
knobs. They comprise the Flies, Gnats and Fleas. 
Fig. 170.—SYRPHUS PYRASTRI. 
A fly (A) whose larva (B) feeds upon the green aphis ; C is the pupa. 
