470 



THE ANIMALS AND MAN 



the glass so as to admit of a layer of soil being placed in the 

 lower part of the cage, and the glass can be made to slide, 

 so as to serve as a door (fig. 238). The glass should fit 

 closely when shut, to prevent the escape of the insects. 



"In rearing caterpillars and other leaf-eating larvae, 

 branches of the food-plant should be stuck into bottles or 

 cans which are filled with sand saturated with water. By 

 keeping the sand wet the plants can be kept fresh longer than 

 in water alone, and the danger of the larvae being drowned 

 is avoided by the use of sand. 



"Many larvae when full-grown enter the ground to pass the 

 pupal state; on this account a layer of loose soil should be 



kept in the bottom of a 

 breeding-cage. This soil 

 should not be allowed to 

 become dry, neither should 

 it be soaked with water. 

 If the soil is too dry the 

 pupae will not mature, or 

 if they do so the wings will 

 not expand fully; if the 

 soil is too damp the pupae 

 are liable to be drowned or 

 to be killed by mold. 



FIG. 238. Soap-box breeding-cage for ,, T . f 



insects It is often necessary to 



keep pupae over winter, for 



a large proportion of insects pass the winter in the pupal 

 state. Hibernating pupae may be left in the breeding-cages 

 or removed and packed in moss in small boxes. Great 

 care should be taken to keep moist the soil in the breeding- 

 cages, or the moss if that be used. The cages or boxes 

 containing the pupae should be stored in a cool cellar, or in 

 an unheated room, or in a large box placed out of doors 

 where the sun cannot strike it. Low temperature is not so 

 much to be feared as great and frequent changes of tem- 

 perature. 



"Hibernating pupae can be kept in a warm room if 

 care be taken to keep them moist, but under such treat- 





