284 STATES OF INSECTS. (Pupa.) 
the time they are ready to emerge, the precise period 
for which these indefatigable nurses are well aware of, 
that they may meet with no obstacle. Without this aid, 
the young ant would be unable to force its way through 
the strong and dense coating of silk that infolds it? 
And a proceeding somewhat akin to this was observed 
by the Hon. Captain Percy, R.N., who himself related 
it tome. Being fond of the study of insects, he was in 
the habit of attending to their motions; and in the be- 
ginning of September 1821 noticed those of a number 
of female Tipule, probably T. oleracea, busily engaged 
in depositing their eggs amongst the roots of grass. 
While observing these proceedings, he at the same time 
saw one quitting its pupa-case, which had already by its 
own efforts got its head, thorax, and anterior legs out of 
it. It was then joined by two male flies; which, with 
their anal forceps and posterior legs taking hold of the 
pupa-case, appeared with their mouths and anterior legs 
to push the little prisoner upwards, moving her back- 
wards and forwards; and as they kept raising her, shift- 
ing their hold of the skin till she was entirely extricated, 
when they left her to recover her strength by herself. 
Probably the extreme length of the two pair of hind-legs 
of these animals may render such assistance necessary 
for their extrication. 
There remains yet to be explained under this head the 
manner in which the perfect insect is excluded from cer- 
tain aquatic pupz; suchas those of Phryganee, gnats, 
and one of those Tipularie that resemble gnats. ‘These 
pupe (perhaps that they may be safe from the attack of 
birds) are destined to remain during the greater part of 
* Huber, Fourmis, 82. 
