260 INSECTS AND MAN 



suitable hiding-place is the precious burden deposited. 

 The ep-gs hatch within the case and the larvae then make 



OO 



their way out, leaving the case to all appearance un- 

 damaged. The larvae are very similar to the adults, except 

 that they are almost colourless, with the exception of their 

 eyes, which are black. Needless to say, these newly 

 hatched larvae are very much smaller than the adults, 

 moreover, they are wingless. Almost immediately after 

 hatching a moult takes place, and with it a darkening in 

 colour ; a second moult takes place four or five weeks later, 

 and a third at the end of the first year. 



Although so common an insect, there is considerable 

 dubiousness as to its length of life and the exact number of 

 moults that take place before the adult stage is reached ; 

 at any rate, after the first year, moults only take place 

 annually, and some observers have stated that the total 

 number is seven. If this be correct, the cockroach is imbued 

 with considerable longevity as insects go. After each 

 moult, at whatever age, the cockroaches are very pale, 

 almost white in colour, and only after the lapse of three or 

 four hours do they resume their typical brownish colour, 

 which, by the way, becomes deeper and deeper with each 

 moult. At the penultimate moult the rudiments of wings 

 appear, and now the insect has reached its nymphal stage. 

 At the final moult, the males acquire their wings, and for 

 the first time in the life-cycle it is possible to distinguish 

 the sexes. It will be observed that there is no pupal stage, 

 such as takes place with the moths and flies, and a meta- 

 morphosis of this nature is said to be incomplete. 



Two other species of cockroach may also be termed 

 domestic : the American cockroach, Periplaneta americana, 

 and a European, though not British, species, Phyllodromia 

 germanica. The latter is well known in the United States, 

 where it has been nicknamed the " Croton bug," and it is 

 also occasionally encountered in England; the 'former, a 

 native of tropical America, is met with from time to time 



