HABITATIONS OF INSECTS. 281 



•own use, but for the convenience of its future young ; and those which 

 are formed by the insect that inhabits them for its own accommodation. 

 To the first 1 shall now call your attention. 



The solitary insects which construct habitations for their future young 

 without any view to their own accommodation, chiefly belong to the order 

 Hj/menoptera, and are principally different species of wild bees and wasps. 

 Of these the most simple are built by Colletes^ succincta, fodicns, he. 

 The situation which the parent bee chooses, is either the dry earth of a 

 bank, or the vacuities of stone walls cemented with earth instead of 

 mortar. Having excavated a cylinder about two inches in depth, running 

 usually in a horizontal direction, the bee occupies it wiih three or four 

 cells about half an inch long, and one sixth broad, shaped like a thimble, 

 the end of one fitting into the mouth of another. The substance of which 

 these cells are formed is two or three layers of a silky membrane, com- 

 posed of a kind of glue secreted by the animal, resembling gold-beater's 

 leaf, but much finer, and so thin and transparent that the color of an 

 included object may be seen through them. As soon as one cell is com- 

 pleted, the bee deposits an egg within, and nearly fills it with a paste 

 composed of pollen and honey; which having done, she proceeds to form 

 another cell, storing it in like manner until the whole is finished, when she 

 carefully stops up the mouth of the orifice with earth. Our countryman 

 Grew seems to have found a series of these nests in a singular situation — 

 the middle of the pith of an old elder branch — in which they were placed 

 lengthwise one after another with a thin boundary between each.'^ 



Cells composed of a similar membranaceous substance, but placed in a 

 different situation, are constructed by Anthidium manicatum? This gay 

 insect does not excavate holes for their reception, but places them in the 

 cavities of old trees, or of any other object that suits its purpose. Sir 

 Thomas Cullum discovered the nest of one in the inside of the lock of 

 a garden-gate, in which I have also since twice found them. It should 

 seem, however, that such situations would be too cold for the grubs with- 

 out a coating of some non-conducting substance. The parent bee, there- 

 fore, after having constructed the cells, laid an egg in each, and filled them 

 with a store of suitable food, plasters them with a covering of vermiform 

 masses, apparently composed of honey and pollen ; and having done this, 

 aware, long before Count Rumford's experiments, what materials conduct 

 heat most slowly, she attacks the woolly leaves of Stachys lanata, Agros- 

 temma coronaria, and similar plants, and with her mandibles industriously 

 scrapes off the wool, which with her fore legs she rolls into a little ball 

 and carries to her nest. This wool she sticks upon the plaster that covers 

 her cells, and thus closely envelops them with a warm coating of down, 

 impervious to every change of temperature."* 



> Melitta*. a. K. 



2 Grew's Rarities of Gresham College, 154. Kirby, Mon. Ap. Angl. i. 131. Melitta*. a. 



3 Curtis, Brit. Ent. t. 61. 



* Man. Ap. Angl. i. 173. Apis.**, c. 2. a. From later observations I am inclined to 

 think that these cells may possibly, as in the case of the humble bee, be in tact formed by 

 the larva previously to becoming a pupa, after having eaten the provision of pollen and 

 honey with which the parent bee had surrounded it. The vermicular shape, however, of 

 the masses with which the cases sre surrounded does not seem easily reconcilable with this 

 supposition, unless they are considered as the excrement of the larva. 



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