EMERGENCE FROM THE COCOON. 
483 
investigate this device in cocoon-making Lepidoptera; it apparently gives 
place to the simpler device of the less strongly woven cocoon from which 
the moth escapes by pushing through the loose fibres and hairs at one 
end ; there are probably many transitional stages from this to the stout 
self-opening cocoon. The Arctiids commonly have loose cocoons as do 
many Noctuids, Pyralids, Tineids, etc. For these, as for many Cole- 
optera, the body of the pupa is set with backwardly directed spines and 
a terminal hook to give the moth the necessary purchase to escape. 
Finally, there are a great number of stout cocoons in which a definite 
lid is provided which comes off. Limacodidce are a conspicuous example 
(fig. 334). In these cases there is a definite line of weakness along the 
wall of the cocoon and we may admire both the instinct of the larva in 
providing it and its ability to so make the cocoon. It occurs also in some 
Braconidce, and in Cionus among Curculionidae. In the latter the larva 
can be seen through the horny cocoon preparing its shelter and leaving 
the line of weakness. By what means the emerging imago ruptures 
the lid is not known, but as little strength is required, there are probably 
as a rule no special devices. In a great number of species, especially 
of Coleoptera , the imago employs its own jaws. The beetle comes out of 
the pupal skin, rests till the chitin is hard and then bites through the 
cocoon or the end of the gallery in which it may be and so emerges. In 
many weevils the true mandibles are provided with false mandibles for 
this purpose, which drop off and leave a scar, after they have been used. 
In the Sawfly Athalia proxima, the imago cuts a lid in the end of the 
tough cocoon with its jaws and then emerges. Most Aculeate Hymenoptera 
do the same, the thin cocoon being bitten through, and this occurs even in 
Megachile, where masonry has to be pierced. 
We have skirted round this fascinating subject in a superficial manner, 
but we may have said sufficient to indicate that there is here great scope 
for observation. There are probably abundant devices as yet unknown, 
and we do not pretend to have even indicated all that are known, but 
there is very little on record for Indian forms. 
Bombycim. 
Proboscis and frenulum absent. Forewing, vein 5 nearer 6 than 4. 
Hindwing vein lc. absent, vein 8 remote from 7, connected 
to or approximating to the cell. 
This family includes only fifteen species of small dull moths] known 
by the bipectinate antennae of both sexes and the hairy spurless legs. 
The proboscis is absent, the antennae are bipectinate in both sexes, the 
legs hairy and without spurs. The larva is elongate, with dorsal humps 
or a terminal horn and is not hairy. A cocoon of silk is formed. 
