May, '02] ENTOMOLOGICAL NEWS. 133 



city to a small \valled-up yard. The benefits which we derive 

 from such labors are a knowledge of the mode of living of the 

 larva in its different stages and the probability of getting per- 

 fect specimens without failures, due to parasites, as might be 

 the case when we collect cocoons at random. We see the last 

 cocoon-spinning caterpillar disappear into its silken .shrine ; we 

 put on a date label of its last performance and fasten the cocoon 

 on the board in such a manner that the fly will not need to 

 pull the whole after him when he tries to emerge. In handling 

 a number of cocoons during the winter we usually find some 

 very light in weight : on opening the cocoon we perceive a 

 shrivelled larva ; the cause is poor nourishment. Where there 

 are many caterpillars to be fed, there are always some which 

 will get plenty to eat and some which will get little. Some 

 larvae, by falling from the top of the breeding cage to the 

 bottom or being disturbed or wet during process of changing 

 into another stage, will be injured and become sick and their 

 appetite will be diminished. Those are the ones that die spin- 

 ning the cocoon. But among so many there will be a few 

 which will try to emerge and never rise above the thorax and 

 die a miserable death. Our friends will say : "Why, you kept 

 them too dry." If we think a moment we will see that this is 

 not the case, because others kept in the same condition made 

 their appearance perfect. They were not too dry, as Nature 

 provided the chrysalis w r ith moisture enough to enable the inseet 

 to change into the adult form and moisture enough is left to help 

 soften the silk in the opening of the cocoon. If the cocoon had 

 been kept too dry the moth never would have been able to come 

 to the surface. The former cases occur mostly with .V. cynthia, 

 only one case was observed of cccmpia. \ large percentage of 

 cocoons opened showed that cynlhia larv;e make the loose ends 

 of the silk very long and plentiful. Coming from a hotu-r 

 climate it may be instinct or reason to shut out the heat of the 

 first few spells of warm weather in spring as much as po^sibk-. 

 As a rule our cecropia and prometlit-a fly earlier than cynthia. 

 A distinguishing mark between the Cynthia and pronictlha 

 cocoon is the flatness at emerging point of the latter, K-ss silk 

 and shorter ends. If the moth, in pushing its way through, is 



