with eggs the capsule is often partly extruded from the female abdo- 

 men and retained in this position sometimes for weeks, or until the 

 young larvae are ready to emerge. The capsule is oval, elongate, or 

 somewhat bean shaped, and one of its edges is usually serrate. The 

 young are in some instances assisted to escape by the parent, who 

 with her feet aids in splitting the capsule on the serrate edge to 

 facilitate their exit. On hatching, it is said the young are often 

 kept together by the parent and brooded over and cared for, and at 

 least a colony of young will usually be found associated with one or 

 two older individuals. These insects are more or less gregarious, 

 notably so in the case of the black beetle of Europe and to a less 

 extent with the German and American roaches. 



They pass through a variable number of molts, sometimes as 

 many as seven, the skin splitting along the back and the insects 

 coming out white, soft, but rapidly 

 hardening and assuming the normal 

 color. Some astounding statements 

 have been made as to the length of 

 time required for the development of 

 the roach from the egg to the adult, f,,, o.-Esg-capsuie of Pcnphoicta 

 Four or five years have been said to be ameHcann-. «, side: /», end view- 



. . , natural size indicated by outline 



necessary tor an indivuai to reach figure (original). 



full growth ; but more recent breed- 

 ing experiments have not altogether confirmed these statements. 

 Their development, however, is unquestionably slow, and probably 

 under the mcjst favorable conditions rarely is more than one genera- 

 tion per year produced. In colder countries the breeding and growth 

 are practically restricted to the warm season. During the winter 

 months they go into concealment and partial hibernation. Ecfobia 

 germanica has been shown to reach full growth in a variable period 

 from four and a half to six months (Hummel, Essais Eiitomologi- 

 ques, No. 1, St. Petersburg, 1821). The common American roach 

 {Periplaneta anievicana) has been carried from the egg to the 

 adult state in our insectary. Young hatching July 1 1 from an egg 

 case received from Eagle Pass, Tex., reached the adult stage between 

 March 14 and Jane 12 of the following year, indicating a period of 

 nearly twelve months for complete development. The rate of growth 

 of the roach undoubtedly depends very largely on food and tempera- 

 ture, and under unfavorable conditions the time required for devel- 

 opment may undoubtedly be vastly lengthened. The abundance of 

 roaches is, therefore, apparently not accounted for so much by their 

 rapidity of multiplication as by their unusual ability to preserve 

 themselves from ordinary means of destruction and by the scarcity 

 of natural enemies. 



