86 PRINCIPAL HOUSEHOLD INSECTS. 



their development. It is supposed that the common oriental cockroach 

 or so-called "black beetle" of Europe [Periplaneta orientalis) 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 [Ectohia 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. mistralasicv), as its name implies, is a native of 

 Australia, and the American roach (P. americana) of 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 may prey uj)on each 

 other, 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 persist- 

 ent groups amoug 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 slii)pery insects, 

 and in shape broad and tlatteiied. The head is intlexed under the body, 

 so that the mouth parts are directed backward and the eyes directed 

 downward, conforming with their groveling habits. The antennae are 

 very long and slender, often having upward of 100 joints. The males 

 usually have two pairs of wings, the outer ones somewhat coriaceous and 

 the inner ones more membranous and once folded longitudinally. In 

 some species, as, for instance, the black beetle, the females are nearly 

 wingless. The legs are long and powerful and armed with numerous 

 strong bristles or spines. The mouth parts are well developed and with 

 strong biting jaws, enabling them to eat all sorts of substances. 



HABITS AND LIFE HISTORY. 



In houses roaches are ])articularly abundant in pantries and kitchens, 

 especially in the neighborhood of fireplaces, on account of the heat. 

 For the same reason they are often abundant in the oven rooms of 

 bakeries or wherever the temperature is maintained above the normal. 

 They conceal themselves during the day behind baseboards, furniture, 

 or wherever security and partial protection from the light are afforded. 

 Their very flat, thin bodies enable them to squeeze themselves into 

 small cracks or spaces where their x>i'esence would not be suspected 

 and where they are out of the reach of enemies. Unless routed out by 



