The Structure and Special Physiology of Insects 15 
tilization is itself accomplished in the lower end of the egg-duct just before the 
egg is laid, by the escape of spermatozoa from the spermatheca (the female 
Fig. 25.—Alimentary canal of larva of harlequin-fly ( Chironomus sp.). oes., oesophagus; 
s.g., salivary gland; ca., cardiac chamber of stomach; mt., Malpighian tubules; ch., 
intestinal chamber; si., small intestine; col., colon. (After Miall and Hammond; 
much enlarged.) 
Fig. 26.—Alimentary canal of two species of thrips; at left Trichothrips copiosa, male, 
at right Aelothrips fasciata. sal.g., salivary gland; oes., oesophagus; prov., proven- 
triculus; vent., ventriculus; m.t., Malpighian tubules; int., intestine; rec., rectum. 
(After Uzel; greatly enlarged.) 
having of course previously mated) and their entrance into the egg through a 
tiny opening, the micropyle (Fig. 67), in the egg-shell and inner envelopes. 
A queen bee mates but once, but she may live for four or five years after 
this and continue to lay fertilized eggs during all this time. She must 
