476 INSTINCT OF INSECTS. 
bark with which its ordinary instinct directs it to make 
its cocoon, substituted pieces of paper that were given 
to it, tied them together with silk, and constructed a 
very passable cocoon with them.—In another instance 
the same naturalist having opened several cocoons of a 
moth (Noctua Verbasci, F.), which are composed of a 
mixture of grains of earth and silk, just after being 
finished; the larvee did not repair the injury in the same 
manner. Some employed both earth and silk; others 
contented themselves with spinning a silken veil before 
the opening?. 
The larva of the cabbage-butterfly (Papilio Bras- 
sicé, LL.) when about to assume the pupa state, com- 
monly fixes itself to the under-side of the coping of a 
wall or some similar projection. But the ends of the 
slender thread which serves for its girth would not ad- 
here firmly to stone or brick, or even wood. In such 
situations, therefore, it previously covers a space of about 
an inch long and half an inch broad with a web of silk, 
and to this extensive base its girth can be securely fast- 
ened. That this proceeding, however, is not the re- 
sult of a blind unaccommodating instinct, seems proved 
by a fact which has come under my own observation. 
Having fed some of these larvae in a box covered by a 
piece of muslin, they attached themselves to this covering; 
but as its texture afforded a firm hold to their girth, they 
span zo preparatory web. 
Apis Muscorum, L., and some other species of humble- 
bees cover their nests with a roof of moss. M. P. Huber 
having placed a nest of the former under a bell glass, he 
* Huvres, ti, 238. See above, p. 259. 
