lepido2)tcrons larvcc and jMpce. 161 



Previously, during larval life, the organism rests motion- 

 less in a curved position on the under side of the leaf, 

 and the body is almost completely hidden by the long 

 white hairs, and the effect is that of a convex mass of 

 white silk spun on to the under side of the leaf, 

 resembling, in fact, a cocoon, or more probably the 

 convex white egg-case spun by a spider. But such an 

 aj^pearance becomes very much the reverse of protective 

 as soon as the larva moves, especially upon a dark back- 

 ground, and the darkening of the larval body alone 

 would be useless, because the hairs form its most con- 

 spicuous feature. 



12. The method by which the imagines of the 



chloephoridie escape from their cocoons. tllc 



various methods by which imagines escape from hard 

 or tough cocoons would be a most interesting subject of 

 research. In maii}^ instances there may be valvular 

 apertures which have hitherto escaped notice, as in the 

 Chloephoridcc. The well-known boat-shaped cocoons of 

 the three English species are very compact and tough, 

 one end being rounded and the other terminating in a 

 vertical ridge, which exactly resembles the bow of a 

 boat, but is not, like the latter, continued into a keel. 

 This sharp ridge is the anterior end of the cocoon, and 

 is in reality a valvular opening with the two lips in 

 contact, and fitting so accurately that they give the im- 

 pression of a single edge, even upon the closest exami- 

 nation. If, however, the cocoon be pressed in the 

 direction of the long axis of the ridge the lips at once 

 separate, and the anterior end of the chiysalis within 

 can be distinctly seen without in any way injuring the 

 cocoon. Such a valve would easily yield to pressure 

 from within, but is practically unassailable from the 

 outside, because, firstly, it is entirely invisible, and 

 secondly, if discovered, it could not be opened by the 

 enemies of the insect. It is very interesting to find 

 such a means of egress from so compact a cocoon, 

 reminding one of the valvular opening to that of S. 

 carpini, but it must be considered as superior to the 

 latter in its perfectly deceptive appearance in addition 

 to at least equal strength. It is well known that the 

 much harder cocoon of U. rriiiila is in some way pierced 

 by the moth, and it seems to have no weak spot through 



