COCKROACHES, ETC. 131 



wood or excrescence of bark. But when excited a 

 wonderful transformation takes place ; the prothorax 

 is raised and the fore-legs are stretched out widely on 

 either side, the wing-covers, wings, and abdomen are 

 raised, the antennae are agitated so rapidly that only 

 an indistinct blur is seen in their place, the fore-tibiae 

 snap down on their femora with clockwork regularity 

 and a continuous rustling sound is kept up by the 

 spread wings ; in addition to all this, the insect sways 

 from side to side : now it is bolt upright, then right over 

 on one side, and then with a swing over on to the other 

 side. The exposed parts are very conspicuously coloured, 

 the under-side of the prothorax is coal-black, the under- 

 sides of the front coxae are deep crimson, the femora 

 bright yellow with a black sickle-like mark on the 

 posterior border and two black spots on the anterior 

 border, the wings are black streaked with hair lines 

 of chrome-yellow. 



How can we account for these brilliant colours and 

 extraordinary attitudes ? I believe that they come into 

 the category of warning colours. Mantidce have many 

 enemies against which their well-armed raptorial claws 

 can be of little protection, and so, like many other 

 insects, (hey defend themselves by the unexpected 

 display of brightly coloured parts. Explain it how we 

 may, it is nevertheless a fact that a sudden alteration 

 in an animal's apearance is very disconcerting and 

 startling even to a human being. I do not think that 

 I have ever been more thoroughly startled than once, 

 when having gently touched a large white caterpillar of 

 the family Lymantriidce, the creature suddenly displayed 

 in the middle of its body a coal-black patch which stood 

 out in startling contrast against the chalk-white of the 



