The Structure and Special Physiology ot Insects i 5 



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 



i-^3- 



-ml. 



Fig. 25. Fig. 26. 



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. — .\Umentary canal of two species of thrips; at left Tricholhrips copiosa, male, 

 at right Aelothrips jasciata. sal.g., salivar}' gland; oes., oesophagus; prov., provcn- 

 triculus; vent., ventriculus; m.t., Malpighian tubules; inl., 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 



