Insects. 689 



Descriptions of the British Species of Leaf- cutter Bees (Megachile of 

 authors) ; with Observations on their Economy. By Frederick 

 Smith, Esq., Curator to the Entomological Society. 



The species belonging to this interesting genus of bees, are popu- 

 larly named leaf-cutters, from their habit of cutting off pieces of the 

 leaves of the rose, elm, and other trees, and using them in the con- 

 struction of the cases in which they deposit the pollen and honey ne- 

 cessary for the food of their larvae. The wonderful mechanical inge- 

 nuity exhibited in the construction of their pollen-cases, attracted the 

 notice of the early naturalists ; and Mr. Kirby has given detailed 

 accounts of his own, as well as of their observations. Various are the 

 situations in which these bees construct their nests ; the same species 

 sometimes choosing trees, posts, or rails in a decaying state, at other 

 times burrowing in banks, or in the mortar of old walls, or availing 

 itself of the interstices from which the mortar has fallen out. A few 

 years ago, Megachile Willughbiella abounded in some old willow 

 stumps in Battersea fields, since destroyed ; these were perforated in 

 all directions by the bees : and as my observations on the develop- 

 ment of this species differ from those of the Rev. Geo. Ashby, given 

 in Mr. Kirby's Monograph, I shall detail them. 



The account alluded to states, that the bee in the lowest cell is the 

 first which arrives at maturity, and that it passes through the bottom 

 of its cell, and so escapes at an opening formed by the provident pa- 

 rent ; the latter, at least, is the inference to be drawn, since, as the 

 cells exactly fit the tube, no other way of escape is possible. But 

 this is quite at variance with my own observations. On one occasion 

 I split off a large portion of one of the old willow trees mentioned 

 above, and in doing so, laid open to view a channel, about eight inch- 

 es long, containing seven cells constructed of rose-leaves. These I 

 preserved for some weeks ; at length a male bee made its escape, and 

 on examination, it proved to have quitted the upper cell. The rest 

 followed in regular succession, three other males and three females. 

 It certainly is possible that the observations alluded to might have 

 been made on a different species ; otherwise the statement is not 

 founded on actual observation. I am not acquainted with any spe- 

 cies of this genus which continues its burrow to the outside of the 

 substance in which it is constructed, as a means of escape for its 

 young brood. M. centuncularis sometimes burrows underground, and 

 as far as my information extends, M. circumcincta always does so. 



