246 HABITATIONS OF INSECTS. 



cieties, built by the united labours of many. The former class may be 

 conveniently subdivided into habitations built by the parent insect, not for 

 its 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 I 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 

 Hymenoptera, and are principally different species of wild bees and wasps. 

 Of these the most simple are built by Colletes 1 succincta,fodiens, &c. 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 with 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, composed of a kind 

 of glue secreted by the animal, resembling gold-beater's leaf, but much 

 finer, and so thin and transparent that the colour of an included object 

 may be seen through them. As soon as one cell is completed, 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. 2 



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, Agro- 

 stemma 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. 4 



i Melitta. *. a. K. 



* Grew's Rarities of Gresham College, 154. Kirby, Mon, Ap. Angl i. 131. Me- 

 litta. *. a. 



3 Curtis, Brit. Ent. t. 61. 



4 Mon. Ap. Angl. i. 173. Apis. **. c. 2. *. From later observations I am inclined 

 to think that these cells may possibly, as in the case of the humble bee, be in fact 

 formed by the larva previously to becoming a pupa, after having eaten the provision 



