65 



cocoon protected by its resemblance to its surroundings, as anyone 

 who has been fortunate enough to find it in its wild state will know 

 full well. The larva feeds on alder and birch, but appears to be most 

 frequently associated with the latter, and the much broken and 

 often lichen-covered bark of the older trees affords splendid oppor- 

 tunities for the construction of well-concealed cocoons. D. finrula, 

 feeding largely on willows and sallows, is in this respect at some 

 disadvantage, often findmg no better position for the construction of 

 its cocoon than a slender branch ; but even then it will frequently 

 select a spot just below a fork in the branch, and so round oft' the 

 ends of the cocoon, and touch up its surface with particles gnawed 

 from the adjacent surface of the branch, as to make an inconspicuous 

 object. (See Plate V., fig. 3.) 



Although the bombyces furnish so many good examples of well 

 protected and highly specialized cocoons, there are among the other 

 macro groups many that are quite interesting. Of the former, Bri/o- 

 phila iiiKi-alis is a good example. I once knew an old bridge wall 

 where this species was very common, and wanting a good series 

 thought I shoula have no difficulty in finding plenty of pup^ng ; but 

 after searching carefully for perhaps half an hour and finding only 

 two or three, I began to appreciate the ingenuity of the larva in con- 

 cealing its cocoon, and found that however keen one's sight might 

 be it was no match against the insect. The sense of touch, 

 however, proved much more productive, and by carefully feeling 

 along the likely crevices in the wall I secured some dozens of 

 cocoons in quite a short space of time. Some of the Acronictas, 

 as for example Acmnicta aZja', protect their pup^e by burrowing in 

 rotten wood, or the soft pith of the branches of some tree, 

 while others spin silken cocoons among rubbish, portions of 

 which are woven in. Pluda nwneta spins among the 

 leaves of its foodplant, an egg-shaped silken cocoon superficially 

 not unlike that of the silk-worm {Boinbyx mori) ; while Cucnllia 

 verbasci, although pupating at some distance below the surface 

 of the earth, constructs a cocoon of silk mixed with large quantities 

 of soil, thus forming thick plaster walls of considerable toughness 

 which it leaves rough and uneven on the outside. Although it is 

 difficult to see any valid reason for this special construction in a 

 subterranean cocoon, so long as it remains in its natural position ; 

 when dug up it may easily be passed over as a small clod of earth ; 

 but apart from its appearance, its toughness is an undoubted 

 advantage to a species, which in common with other members of the 

 genus which construct similar cocoons, often remains in pupa for 

 more than one winter. 



Among the Geometrse also there are some interesting examples ; 

 notably the beautiful hammock-like structure made by Urapteiyx 

 sambucaria, and the tight-fitting sack-like cocoon of Pericallia 

 syriiujaria, so often finished off with a piece of dead leaf attached to 

 one end, which materially assists in its concealment. Also, there 



