THE PUPA. 55 



of earth, but most species spin oblong silken cocoons. 

 The species of Selandria, &c.,mix the silk with grains 

 of earth. The Cimbicides spin double cocoons, an 

 inner one inside an outer more tenacious covering, 

 the inner one being separated from it by a clear 

 space. Some species of Nematus likewise form double 

 cocoons, but not all. Those of Cladius are irregular 

 in shape, thin, and almost transparent. The outer case 

 of the cocoon of ClaveUaria is also of an open texture. 

 Cinibex and Trichiosoma spin their cocoons on the 

 branches of the food plants ; Nematus gallicola in 

 masses under chinks of bark on the food plant, 

 ( ' njptocanipuspentandrce in the galls ; but most species 

 spin them in the earth. 



After being in the cocoon the larva in a short 

 time shortens and contracts its shape, the legs at 

 the same time being withdrawn into the skin as it 

 were. The period which elapses between the spinning 

 of the cocoon and becoming a pupa varies according 

 to the season. "With the summer broods it may be 

 from seven to ten days, but the autumnal broods do 

 not change until the following spring, so that the 

 greater part of their larval existence is spent in this 

 inert condition. In exceptional cases they may even 

 remain two years in the cocoon before changing. 



The larvae are very much preyed upon by ichneumon 

 and dipterous flies (Taclima and its allies). The ich- 

 neumons belong principally to the Tryphonides, which, 

 indeed, would appear to be specially attached to saw- 

 fly larvae. Braconidce are not often bred from them ; 

 the Ophionides are not uncommon, while many Chalci- 

 didce as well as Pimplides are reared from the gall- 

 making Nemati. 



The Pupa 



Bears a considerable resemblance to the perfect insect. 

 The antennse are placed along the front, the legs along 

 the breast, while the wings appear as pad-like struc- 



