416 ELEMENTARY BIOLOGY 



Ants and cockroaches are always a nuisance about a house 

 and can be exterminated, once they get in, only through care- 

 ful attention to their nests, cracks in the walls, etc., and to the 

 availability of material that will attract them. Corrosive sub- 

 limate is used to poison them, solutions being sprinkled into 

 the cracks. The cockroaches can be driven out by systemati- 

 cally sprinkling borax about the kitchen. 



Weevils, small beetles with beaks, are very destructive to 

 stored grains, beans and peas, etc. There are many different 

 species, and they are all destructive. Infested granaries and 

 warehouses need to be thoroughly fumigated with carbon 

 bisulphid, which kills the eggs and the larvae as well as the 

 adults (see Fig. 219, e). 



Flour is often spoiled by other beetles, as the rpeal-worm 

 (the larva of a black beetle, Tenebrio (Fig. 215)), and by a 

 species of moth, Ephestia knehniella (Fig. 216). 



Another destructive beetle is the so-called buffalo motk, 

 shown in Fig. 217. The larva of this carpet beetle is very 

 destructive to rugs and other woolen material. 



