COCKROACHES 



(Family Blattida.) 



The insects of this family, known commonly as cockroaches, 

 form the old group Cursoria, or runners. The body as a rule is 

 oval and flat, all the legs being similar in form. The head is de- 

 flexed or bent under and generally concealed by the prothorax. 

 The hind wings are 

 slightly folded. The 

 insects of this group 

 are very abundant in 

 the tropics but several 

 species have become 

 domesticated and are 

 very abundant in the 

 colder parts of the 

 world. The cock- 

 roach type is a very 

 persistent one, and in- 

 sects of this family 

 existed in great num- 

 bers in geologic 

 periods prior to the 

 tertiary. They are 

 found in considerable 

 number in carbonif- 

 erous rocks and one 

 form has been found 

 in Silurian sandstone. 



The eggs are laid 

 in egg cases as with 



the Mantidae but the subsequent life history is little known, It is 

 supposed that they grow very slowly. Most of them are 

 nocturnal in their habits. They feed on a great variety of 



329 



Fig. 217. Periplaneta americana. 

 ( Redrawn from Marlatt.) 



