IN CATERPILLARS 229 



This same feature occurs in some of our own 

 species of Brenthis as I have several times ob- 

 served. It is also found in some of the Melitae- 

 ini, and I suspect also in the genus Argynnis, 

 from the fact that there are in some places two 

 apparent broods of the butterfly, months apart, 

 but only one period of egg-laying. Since in these 

 cases the winter is passed in the larval condition, 

 the caterpillar just from the egg^ it would appear 

 probable that lethargy makes its appearance in 

 the spring and early summer among the growing 

 caterpillars, or else, what seems less likely, the 

 period passed in chrysalis is very unequal. 



It is possible that to this list should be added 

 those Theclini and Chrysophanini which ostensibly 

 pass the winter in the egg state. If, as is prob- 

 able, these eggs mature during the hot season 

 in which they are laid, and not in the succeeding, 

 cooler, early spring when the caterpillar escapes, 

 then the oidy difference between these caterpillars 

 and those of the Argynnini is that one passes the 

 winter within, the other without the egg-shell ; 

 and their refusal to escape in the warm weather 

 points to premature hibernation, beginning in a 

 kind of lethargy. 



The cause of this strange feature in butterfly 



