L 



The Cotton-bees 



cylinder wherein ten cocoons are lodged in a 

 row comes an empty space of half a decimetre 

 or more/ The Osmiai and the Leaf-cutters 

 are also accustomed to leave these long, de- 

 serted vestibules. The nest ends, at the 

 orifice of the reed, with a strong plug of flock 

 coarser and less white than that of the cells. 

 This use of closing-materials which are less 

 delicate in texture but of greater resisting- 

 power, while not an invariable characteristic, 

 occurs frequently enough to make us suspect 

 that the insect knows how to distinguish what 

 is best suited now to the snug sleeping-berth 

 of the larvae, anon to the defensive barricade 

 of the home. 



Sometimes the choice is an exceedingly 

 judicious one, as is shown by the nest of 

 the Diadem Anthidium. Time after time, 

 whereas the cells were composed of the 

 finest grade of white cotton, gathered from 

 Ccntaurca solslicialis, or St. Barnaby's thistle, 

 the barrier at the entrance, differing from 

 the rest of the work in its yellow colouring, 

 was a heap of close-set bristles supplied by the 

 scallop-leaved mullein. The two functions of 

 the wadding are here plainly marked. The 



'About two inches. — Translator's Note. 



283 



