HABITATIONS OF INSECTS^. 437 



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

 placed lengthwise one after another Avith a thin boun- 

 dary between each ^. 



Cells composed of a similar membranaceous sub- 

 stance, but placed in a different situation, are con- 

 structed by Apis manicata. 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 tlie 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 without a coating of some non- 

 conducting substance. T!ie parent bee, therefore, af- 

 ter having constructed the cells, laid an e^g 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 Stachi/s lanaia^ Agrostemma corona^ 

 rla, and similar plants, and with her mandibles in- 

 dustriously 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 coat- 

 ing of down impervious to every change of tempera- 

 ture^. 



^ Grcrv's liaritie/i of GreSliayn Colkdge, 154. Kirby Mon. yfp. jtngL 

 i. 131. Melilla. *■ a. 



' " Moi}. ytp. yingl. i. 173. j4pis * *. c. 2. tc. From later observations I 

 r.m inclined to think that these cells may possibly, as in the ra=e of the 

 j}.!mbie-bec, be in fact formed by the larva previously to becoming ."i 



