Cockroaches 



substances, especially those forms which inhabit houses, but it 

 is supposed that their natural food is dead animal matter. Dr. 

 Sharp estimates that there are five thousand species in existence. 

 The species found in American houses are the American cock- 

 roach ( Periplaneta americana), the German cockroach or croton 

 bug (Ectobia germanica), the European cockroach or "black 

 beetle" as it is known in England (Periplaneta orientalis) and the 

 Australian cockroach (Periplaneta australasice). The egg cases 

 of the German cockroach is shown in accompanying illustrations. 

 The female carries the egg case with her until she finds a 

 proper place to leave it or until the eggs are nearly ready to hatch. 

 The young roaches grow slowly and pass through a variable 



Fig. 218. — Ectobia germanica. ( Redrawn from Insect Life.) 



number of molts, sometimes as many as seven. The time re- 

 quired for the development from the egg to the adult may be pro- 

 longed by absence of food or low temperature. Four or five 

 years have been said to have been occupied in this growth. 

 The German cockroach has been shown to reach full-growth in 

 from four and one-half to six months and the American cockroach 

 has been raised from the egg to the adult in about twelve months. 

 No sufficiently careful observations on the life history of the 

 common species appear to have been made, hence the "Typical 

 Life History " must be omitted with the insects of this family. 

 The anatomy of Periplaneta orientalis has been carefully studied 

 by Miall and Denny.* and the American household cockroaches 

 have been treated at some length by Marlatt.** 



*The Anatomy of the Cockroach. 



**Bull. 4, N. S., Div. Entomology, U. S. Dept. Agric, pp. 84-95. 



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