HABITATIONS OF INSECTS. '437 



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

 lengthwise one after another with a thin boundary be- ' 

 tween each 3 . 



Cells composed of a similar membranaceous substance, 

 but placed in a different situation, are constructed by 

 Apis manicata, L. 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 without 

 a coating of some non-conducting substance. The pa- 

 rent bee, therefore, 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 experi- 

 ments, what materials conduct heat most slowly, she at- 

 tacks the woolly leaves of Stachys lanata, Agrostemma 

 coronaria, 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 coating of 

 down impervious to every change of temperature b . 

 The bee last described may be said to exercise the 



a Grew's Rarities of Gresham Colledge, 154. Kirby Mon. Ap. 

 Angl.'x. 131. Melitta.*. a. 



b Mon. 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 fact formed by the. larva previously to becom T 



