62 



growing leaf of an oak-tree. When the winds blow, as they often 

 do even in summer, the leaves are driven one against the other with 

 considerable force ; and it is, therefore, necessary for the safety of 

 the pupa that the cocoon in which it is contained should be able to 

 withstand the sudden and often considerable pressure that is thus 

 put upon it. This is accomplished by its peculiar shape. It is 

 exactly like an upturned boat constructed of material having the 

 appearance of very thin parchment ; the gunwale attached to the 

 leaf, the keel and bilge pieces extending along its back and sides, a 

 construction that gives great rigidity. So long as it is intact it will 

 withstand very considerable pressure, but when the imago has 

 escaped, which it does by splitting up the front end of the cocoon, 

 which corresponds to the bow of the boat, its loses it rigidity and 

 may be easily crushed, thus showing that its resisting power is due 

 to its highly specialized construction, rather than to the material of 

 which it is made. 



Earia.<< chlnrana, an allied but smaller species, spins a cocoon on 

 somewhat similar lines, but on a much less elaborate scale. The 

 larva feeds in the leading shoots of the osier {Sali.v vwiinalifi), and 

 when about to pupate descends to the hard-wooded branches or 

 stem of the tree, the bark of which it gnaws up and mixes with the 

 material of which it makes the cocoon, the object apparently 

 being concealment rather than great strength. Some years 

 ago I had rather a curious experience with this species. I 

 was staying at Eastbourne, and having collected a considerable 

 number of osier shoots containing larvae, 1 put them in a large 

 cylindrical tin which bad, I believed, an absolutely close fitting lid. 

 Having to go to London for a few days, I put the tin in a cupboard 

 of a sideboard at the rooms where we were staying. On opening 

 the tin on my return I found the osier shoots well eaten but not a 

 larva was to be seen among them. Naturally, I made a search for 

 them, but could find no wandering larv^ either in or about the 

 cupboard. In the course of my investigations, however, I detected 

 certain slight irregularities in the surface of the wood of which the 

 cupboard was made, and upon closer investigation found that they 

 were caused by the cocoons of the H. cJdorana. Evidently the 

 larvfe had become full-fed during my absence, and finding no 

 suitable substance within the tin on which to construct their cocoons, 

 they had exercised their Tortrix-like propensities and squeezed 

 themselves through some tiny crevice, where the lid was not an 

 exact fit, in search of a likely spot for pupation — which the soft 

 wood of the cupboard provided. Now the most interesting part of 

 the story has yet to come. This particular cupboard, as is the case 

 with many articles of cheap furniture, was lined with a soft white 

 wood painted over with some pinkish substance, and the larvae in 

 making their cocoons had so managed to work this in that they 

 matched the surrounding surface so exactly that it was almost 

 impossible to detect them by sight ; not so, however, the little white 



1 



