40 Insect Architecture. 



Our nest contained only two cells perhaps from there not 

 being room between the bricks for more. 



[There are only four British species of this genus. One 

 species, A. acervorum, seems perfectly indifferent whether it 

 burrows into banks or into the mortar of old walls. If 

 possible, the former locality seems to be the most favoured. 



This species is notable for the many parasites who infect 

 the habitation and destroy the inmates. Perhaps the very 

 worst and most destructive of these parasites is the common 

 earwig, which wreaks wholesale desolation in the nest. It 

 creeps into the burrow, and if it finds a store of pollen laid up 

 for the young, it will eat the pollen. But if the young grub be 

 hatched it will eat the grub. If the inmate be in the pupal 

 state, or even if it be ready to emerge in its perfect condition, 

 the earwig will eat it. 



There are two bees which are parasitic upon this unfor- 

 tunate insect, both belonging the genus Melecta. 



But the most destructive of these parasites appears to be an 

 insect which belongs to the great family of Chalcididce. These 

 insects are of the hymenopterous order, are of very minute 

 dimensions, and of the most brilliant colours. Indeed, if 

 they were an inch or two in length, instead of the eighth or 

 twelfth of an inch, they would not suffer in comparison with 

 the most gorgeous inhabitants of tropical countries. 



Their forms are most eccentric, some species having the 

 abdomen small and round and set on a long foot-stalk, while 

 others have that portion of the body placed so closely against 

 the thorax, that the short footstalk is scarcely visible. Others 

 have certain joints of the legs so large that a single joint 

 equals the entire abdomen. Some have the ovipositor pro- 

 jecting boldly from the body, while others have it tucked up 

 underneath, and others again have it quite short. But there 

 is one point which distinguishes them all, namely, the almost 

 veinless character of the wings. 



Some of the Chalcididce are parasitic upon insects in their 

 earliest stages, actually depositing their eggs in those of 

 moths and butterflies. Others are entirely parasitic upon 

 parasites, laying their eggs in the aphidii, which are parasites 



