10 INJURIOUS AND USEFUL INSECTS 



readily displayed by drawing out the extremity of the abdomen 

 with a pair of forceps ; these are ordinarily concealed beneath 

 the seventh tergum. The hind margin of the tenth tergum is 

 deeply notched. Seven abdominal sterna (1-7) are externally 

 visible. The first is only vestigial, being reduced to a small 

 transverse plate ; the second is of irregular outline, soft and 

 flexible in front; the seventh is large, and its hinder-part, 

 which is boat-shaped, is divided into lateral halves, and can be 

 widely dilated for the reception of the large egg-capsule. In 

 the male cockroach ten abdominal terga are visible without 



Fii^. 7. — Young larva of cock- 

 roach (male). X 6. 



Fig. 8. — Older larva of cockroach 

 (male) with rudiments of wings. 



X 2*. 



dissection, though the eighth and ninth are almost hidden by 

 the seventh. The tenth tergum is hardly notched. Nine 

 abdominal sterna can be readily made out, the first being 

 rudimentary, as in the female. The ninth sternum carries a 

 pair of small styles, which project beyond the end of the body. 

 Look for the spiracles, or apertures by which air is taken 

 into the tracheae. In the abdomen the spiracles lie in the 

 flexible membrane which connects one segment with the next. 



