MEANS OF DEFENCE OF INSECTS. 427 
deed, I have often found other kinds asleep. Linné named another species 
florisomnis on account of a similar propensity. A third, a most curious 
and rare species (Andrena1 spinigera), shelters itself when sleeping, at 
least I once found it there so circumstanced, in the nest-like umbel of the 
wild carrot. You would think it a most extraordinary freak of nature, 
should any quadruped sleep suspended by its jaws (some birds, however, 
are said, I think, to have such a habit, and Sus Babyroussa one something 
like it), —yet insects do this occasionally. Linné informs us that a little 
bee (Epeolus? variegatus) passes the night thus suspended to the beak of 
the flowers of Geranium pleum: and I once found one of the vespiform 
bees (Nomada* Goodeniana) hanging by its mandibles by the edge of a 
hazel-leaf, apparently asleep, with its limbs relaxed and folded. On being 
disengaged from its situation it became perfectly lively. 
There is no period of their existence in which insects usually are less 
able to help themselves, than during that intermediate state of repose 
which precedes their coming forth in their perfect forms. I formerly ex- 
plained to you how large a portion of them during this state cease to be 
locomotive, and assume an appearance of death. In this helpless con- 
dition, unless Providence had furnished them with some means of security, 
they must fall an easy prey to the most insignificant of their assailants. 
But even here they are taught to conceal themselves from their enemies 
by various and singular contrivances. Some seek for safety by burying 
themselves, previously to the assumption of the pupa, at a considerable 
depth under the earth; others bore into the heart of trees, or into pieces 
of timber; some take their residence in the hollow stalks of plants: and 
many are concealed under leaves, or suspend themselves in dark places, 
where they cannot readily be seen. But in this state they are not only 
defended from harm by the situation they select, but also by the covering 
in which numbers envelop themselves ; for besides the leathery case that 
defends the yet tender and unformed imago, many of these animals know 
how to weave for it a costly shroud of the finest materials, through which 
few of its enemies can make their way ; —and to this curious instinct, as I 
long since observed, we owe one of the most valuable articles of commerce, 
the silk that gives lustre to the beauty of our females. These shrouds are 
sometimes double. Thus the larve of certain saw-flies spin for them- 
selves a cocoon of a soft, flexible, and close texture, which they surround 
with an exterior one composed of a strong kind of net-work, which with- 
stands pressure like a racket.4 Here nature has provided that the in- 
closed animal shall be protected by the interior cocoon from the injury it 
might be exposed to from the harshness of the exterior, while the latter 
by its strength and tension prevents it from being hurt by any external 
pressure, 
But of all the contrivances by which insects in this state are secured from 
their enemies, there is none more ingenious than that to which the May- 
flies (Trichoptera) have recourse for this purpose. You have heard before 
that these insects are at first aquatic, and inhabit curious cases made of 
a variety of materials, which are usually open at each end. Since they 
Must reside in these cases, when they are become pup, till the time of their 
final change approaches, if they are left open, how are the animals, now 
* 
1 Melitta, **. c. K. 2 Apis. **.b. K, 
8 Anis. b. * K, 4 Reaum. y. 100. 
