SOME USEFUL INSECTS. 241 



ground. They then throw over the mouse the 

 earth they have excavated till the whole body is 

 covered up. 



When this is done the female beetle lays her 

 eggs in the body of the buried mouse. 



After the female beetle has laid her eggs and 

 both beetles have had a good feed, the two parent 

 beetles crawl out of the hole, and cover it up 

 carefully so as to conceal the hiding-place. 



Not only then are these beetles great purifiers 

 and scavengers, but by burying dead bodies a 

 little way beneath the soil, the bones in decaying 

 manure the surface soil, and thus they are a 

 help to agriculturalists. 



How do these insects find out that there lies a 

 mouse awaiting eating and burial ? Is it done 

 by sight, or is it done by smell, or by both com- 

 bined, or is it done by some other sense of which 

 at present we know nothing ? 



We do know that everything that lives on 

 flesh has a powerful sense of smell. 



Wasps. Although these insects are fond of 

 fruit they do a deal of good by destroying 

 a number of injurious insects, and by purifying 

 decaying and obnoxious matter. 



The nests of some wasps are built in the 

 hollows of trees, others hang freely down from 

 the trees. When the nests hang down, their 

 combs and cells are made of papery substance. 



Q 



