That roaches will eat fruits and the starchy tubers and other prod- 

 ucts of plants is a common observation, but that they ever subsist 

 on the green foliage 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 early 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 to the multiplication of this family of insects. 



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

 with man in his primitive dwellings, and through the agency of com- 

 merce have followed him wherever navigation has extended. In fact, 

 on shipboard they are always especially numerous and troublesome, 

 the moisture and heat of the vessels being particularly favorable to 

 their development. It is supposed that the common Oriental cock- 

 roach, or so-called "black-beetle," of Europe (Blatta orientalis L.), 

 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 {Blattella germanica L.) 

 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 civili- 

 zations of Asia and Egypt. 



Of the other two domestic species especially considered in this 

 paper, the Australian roach (Periplaneta australasise Fab.), as its 

 name implies, is a native of Australia, and the American roach (P. 

 americana 1j.), 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 species, while in the other a distinct species is the 

 commoner one. The different species are thus seemingly somewhat 

 antagonistic, and it is even supposed that they nuiy prey upon one 

 another, the less numerous species being often driven out. 



STRUCTURAL CHARACTERISTICS. 



Although among the oldest insects geologically, roaches have not 

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

 sistent groups among insects. The house species are rather uniformly 

 dark brown or dark colored, a coloration which corresponds with their 

 habit of concealment during daylight. They are smooth and slippery 

 insects, and in shape broad and flattened. The head is inflexed under 



[Cir. 51] 



