ITS NATURAL HISTORY. 



stages, but are then rudimentary, and constitute a mere pro- 

 longation of the margins of the thoracic rings. Cornelius says 

 that the round white spot internal to the antenna first appears 

 plainly in the pupa, but we have readily found it in a very 

 young larva. The Insect is active in all its stages, and is 



Fig. 7. Older nymph (male) with rudiments of wings. X 2|. 



therefore, with other Orthoptera, described as undergoing 

 " incomplete metamorphosis." After each moult it is for a few 

 hours nearly pure white. Of the duration of life in this species 

 we have no certain information, and there is great difficulty in 

 procuring any. 



Sexual Differences. 



Male Cockroaches are readily distinguished from the females 

 by the well-developed wings and wing-covers. They are also 

 slighter and weaker than the females ; their terga and sterna 

 are not so much thickened ; their alimentary canal is more 

 slender, and they feed less greedily (the crop of the male is 

 usually only half- full of food). They stand higher on their legs 

 than the females, whose abdomen trails on the ground. The 

 external anatomical differences of the sexes may be tabulated 

 thus : 



