114 



BULLETIN 67, UNITED STATES NATIONAL MUSEUM. 



others one must be particular about fresh food, sunlight, and ven- 

 tilation. The amount of moisture necessary for the proper develop- 

 ment and expansion of the wings varies, and one must learn this by 

 experience. A wet sponge or blotting paper will give a supply of 



moisture. One should be care- 

 ful not to put too much food in 

 the cage at one time, as it may 

 mold and injure the larva. 

 Some larvae feed better in a 

 darkened place. This may be 

 simulated by wrapping the 

 jelly glass or other cage with a 

 piece of black muslin. Other 

 larvse will feed only at night, 

 and should have some soil 

 or litter in the bottom of 

 the box under which they 

 may conceal themselves dur- 

 ing the day. After once 

 starting a larva on a certain 

 food plant it is not well to 

 change it, although it can 

 sometimes be done with 

 safety, and seems to be 

 preferred by a few cater- 

 pillars. 



Sometimes it is impossible to obtain the ordinary food plants of 

 the larvse, and one must resort to a substitute food plant. Often an 

 allied plant will give satisfactory results. If, for example, a larva 





Fig. 170.— An insect breeding-cage, ok vivarium. 



Fig. 171.— The improved base for breeding-cage. 



should feed on apple, and this can not be had, one may discover that 

 an allied larva feeds on walnut, or both apple and walnut; then 

 walnut ma}^ be the substitute for apple in the first case. There are a 



