tion, but that the}' ever subsist on the green foHage of plants may 

 be open to doubt. • 



The roach is one of the most primitive and ancient insects, in the 

 sense of its early appearance on the globe, fossil remains of roaches 

 occurring in abundance in the earl}^ coal formations, ages before the 

 more common forms of insect life of the present day had begun to 

 appear. The species now existing are few in number in comparison 

 with the abundance of forms in the Carboniferous age, which might 

 with propriety be called the age of cockroaches, the moisture and 

 warmth of that distant period being alike favorable to plant growth 

 and the multiplication of this family of insects. 



The house roaches of to-day were undoubtedly very early associa- 

 ■^ted with man in his primitive dwellings, and through the agency of 

 .'ommerce have followed him wherever navigation has extended. In 

 fact, on shipboard they are alvva3's especially numerous and trouble- 

 some, the moisture and heat of the vessels being particularly favor- 

 able to their development. It is supposed that the common Oriental 

 cockroach, or so-called "black-beetle" of Europe {Periplaneta 

 oi'ifntalis), is of Asiatic origin, and it is thought to have been 

 introduced into Europe in the last two or three hundred years. The 

 original home of this and the other common European species 

 {Ectobici germanica) is, however, obscure, and in point of fact 

 they have probably both been associated with man from the earliest 

 times, and naturally would come into the newly settled portions of 

 Europe from the older civilizations of Asia and Egypt. 



Of the other two domestic species especially considered in this 

 paper, the Australian roach (P. australasice), as its name implies, 

 is a native of Australia, and the American roach (P. ainericana) 

 of subtropical and tropical America. 



Rarely do two of the domestic species occur in any numbers 

 together in the same house. Often also of two neighboring districts 

 one may be infested with one s])ecies, while in the other a distinct 

 species is the commoner one. The different species are thus seem- 

 ingly somewhat antagonistic, and it is even supposed that they may 

 prey upon each other, the less numerous species being often driven 

 out. 



STRUCTURAL CHARACTERISTIC'S. 



Although among the oldest insects geological!}', roaches have not 

 departed notably from the early types, and form one of the most 

 persistent groups among insects. The house species are rather uni- 

 formly dark brown or dark colore<l, a coloration which corresponds 

 with their habit of concealment during daylight. They are smooth 

 and slipper}' insects, and in shape broad and flattened. The head is 

 inflexed under the body, so that the mouth parts are directed back- 



