BLATTA OKIENTALIS. 97 



change occurs, the skin cracks along the back of the 



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thorax, and the imago slowly and carefully draws itself 

 out. As after each moult (ecdysis), it is at first 



white, but in about three davs it attains its full colour. 



(/ 



The nymph, which in appearance closely resembles 

 the female imago, is, like her, almost black in colour. 



DATE. Living under artificial conditions of warmth 



o 



and protection, 13. oriental i* is probably continuous- 

 brooded, though it is of course possible that inherited 

 habits may keep it to its natural breeding season. 



HABITS, ETC.- -Coming no doubt from a warmer 

 climate than our own, the common cockroach seeks 

 out spots for a habitation where a genial temperature 

 is fairly continuous. Hence its predilection for kitchens, 

 bakehouses, Zoological Gardens, etc., where, in addition 

 to the warmth, food is easily procurable. It is an 

 omnivorous feeder, scarcely anything coming amiss- 

 ink, blacking, the film on photographic plates, its dead 

 companions, cast-skins, and empty oothecse. Cucumber, 

 we are told, disagrees with it, and, according to some, 

 phosphorus-paste is fatal. If B. oi-i<'nt(iU* gets access 

 to human food it spoils more than it eats, owing to the 

 unpleasant odour left behind it. In its habits it is 

 nocturnal, hiding in narrow crevices during the day, 

 its flattened build specially fitting it for so hiding. 

 Still the cockroach has some compensating points- -it 

 is a useful scavenger, and an enemy of the bed-bug. 

 TTe have been told that it has been employed in 

 medicine, and that it even has a pleasant taste ; but 

 its great use is in the biological laboratory. There 

 great numbers are dissected: for B. orientalis is 



o 



readily obtainable and at the same time serves admir- 



/ 



ably as the type of an insect in a fairly unspecialised 

 state. 



Though it has been taken out of doors occasionally, 

 there seems to be little, or no, tendency towards 

 acclimatisation in Britain. On very warm nights it 



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no doubt often conies out into the open air ; but it has 

 once or twice been met with farther afield than this. 



7 



