SPINNING CATERPILLARS. 285 



as if at random, to the bits of pollen which remained imde- 

 voiired, and afterwards tumbling about to another part of 

 the box, as if dissatisfied with what it had done. It some- 

 times persevered to spin in one place till it had formed a 

 little vaulted wall ; but it abandoned at the least three or 

 four of these in order to begin others, till at length, as if 

 compelled by the extreme urgency of the stimulus of its 

 approaching change, it completed a shell of shining brown 

 silk, woven into a close texture. Had the grub remained 

 within the narrow clay cell built for it by the mother bee, 

 it would, in all probability, not have thus exhausted itself 

 in vain efforts at building, which were likely to prevent it 

 from ever arriving at the perfect state — a circumstance 

 which often happens in the artificial breeding of insects. 

 This bee, however, made its appearance the following 

 spring. (J. E.) 



Beside silk, the cocoons of many insects are composed of 

 other animal secretions, intended to strengthen or otherwise 

 perfect their texture. We have already seen that some 

 caterpillars pluck off their own hair to interweave amongst 

 their silk ; there are others which produce a peculiar sub- 

 stance for the same purpose. The lackey caterpillar ( Clisio- 

 campa neustria, Curtis) in this manner lines its cocoon 

 with pellets of a downy substance, resembling little tufts of 

 the flowers of sulphur. The small egger, again {Eriogaster 

 lanestris, Germab), can scarcely be said to employ silk at 

 all, — the cocoon being of a uniform texture, looking, at first 

 sight, like dingy Paris plaster, or the shell of a pheasant's 

 egg ; but upon being broken, and inspected narrowly, a few 

 threads of silk may be seen interspersed through the whole. 

 In size it is not larger than the egg of the gold-crested 

 wren. It has beea considered by Brahm a puzzling cir- 

 cumstance, that this cocoon is usually perforated with one 

 or two little holes, as if made by a pin from without ; and 

 Kirby and Spence tell us that their use has not been ascer- 

 tained.* May they not be left as air-holes for the included 

 chrysalis, as the close texture of the cocoon might, without 

 this provision, prove fatal to the animal? Yet, on com- 

 * Bralim's Ins. Nat. 289, and Kirby and Spencc's Intr. iii. 223. 



