170 EN TOMOLOGY 
twig; Tropea luna and Telea polyphemus spin among leaves, 
and their cocoons (with some exceptions) fall to the ground; 
Callosamia promethea, whose cocoon is covered with a curved 
leaf, fastens the leaf to the twig with a wrapping of silk, so 
that the leaf with its burden hangs to the twig throughout the 
winter. The leaves surrounding cocoons may render them 
inconspicuous or may serve merely as a foundation for the 
cocoon. While silk and often a water-proof gum or cement 
Grea sys 
Cocoon of Samia cecropia, cut open to show the two silken layers and the enclosed 
pupa. Natural size. 
form the basis of a cocoon, much foreign material, such as bits 
of soil or wood, is often mixed in; the cocoons of many com- 
mon Arctiide, as Diacrisia virginica and [sia isabella, consist 
principally of hairs, stripped from the body of the larva. 
Butterflies have discarded the cocoon, the last traces of 
which occur in Hesperiidee, which draw together a few leaves 
with a scanty supply of silk to make a flimsy substitute for a 
cocoon. Papilionid and pierid pupz are supported by a silken 
girdle (Fig. 27), and nymphalid chrysalides hang freely sus- 
pended by the tail (Fig. 212). 
Cocoon-Spinning.—The caterpillar of Telea polyphemus 
“feels with its head in all directions, to discover any leaves 
to which to attach the fibres that are to give form to the co- 
coon. If it finds the place suitable, it begins to wind a layer 
