MEANS OF DEFENCE OF INSECTS. 427 



deed, I have often found other kinds asleep. Linne named another species 

 fiorisomnis on account of a similar propensity. A third, a most curious 

 and rare species (^Andrena ^ 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 Babyroitssa one something 

 like it), — yet insects do this occasionally. Linne informs us that a little 

 bee {Epeolus ^ variegatus) passes the night thus suspended to the beak of 

 the flowers of Geranium phceum : and I once found one of the vespiform 

 bees (Nomacla * 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 tlieir 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 

 i'ew 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 laryas 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.* 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 {Trichopterd) 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 pupae, 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. 



3 Apis. b. • K. 4 Keaum. v. 100. 



