100 SOCIAL HABITATIONS. 
In the present example, the larva has permitted the 
cocoon to be made, and then killed the caterpillar, the 
reason of this delay being that the cocoon is very firm 
and strong, and affords an impregnable shelter to the 
parasite. 
Within the same case there are several cocoons in 
which a similar calamity has befallen the caterpillars 
which made them. There is, for example, a cocoon of 
the Oax-Eacer Mors, the interior of which resembles 
that of the insect which has just been described, except 
that the cells of the parasite are more numerous. This 
species of caterpillar is peculiarly subject to the attacks 
of the ichneumon flies, as is well known to all practical 
entomologists, who lose many of their carefully-bred 
specimens by means of these insects. 
There is also one of the winter cocoons of the Goat Motu 
caterpillar, the inmate of which has been pierced by the 
ichneumon fly, and killed by its young. As the species 
of ichneumon is a large one, only a single individual 
was produced, and as may be seen from the cell of the 
parasite which is placed by the side of its victim, the 
habitation of the ichneumon is so large that it must 
have occupied nearly the entire cocoon of the dead cater- 
pillar. 
In another room, placed among the series of British 
moths, is a cocoon of a Puss Motu, which has been occu- 
pied by two ichneumon larve. 
If the reader should happen to know the cocoon of this 
moth, he will remember that it is made of wood-scrapings, 
glued together with a cement secreted by the insect, and 
that its walls are so hard that a tolerably strong knife is 
required in order to cut it open. That the eggs of a parasite 
