26 



PSYCHE. 



[February 1S94. 



second years' growth of raspberry stems. 

 The nest usuallv consists of several 

 cells, separated from each other by parti- 

 tions at regular intervals and filled with 

 a kind of honey-paste upon which the 

 larvae feed. The larvae transform into 

 iiiiagos the last of July or during August. 



From this bee. the Rev. J. L. Zabris- 

 kie has bred two interesting parasites, 

 Diamoriis zabriskii Cr. and Axima 

 zab}-iskii How. ; while Dr. Packard 

 also records a species of Melittobia 

 (^Antliophorabia) from this bee. 



The genus Megachile represents the 

 leaf-cutting bees, so called from the pe- 

 culiar habit of the female in cutting 

 small, more or less circular, pieces out of 

 the tender leaves of various plants where- 

 with to line its cells. These cells are 

 placed in burrows made in the ground 

 or in wood. 



Mr. F. W. Putnam in "Notes on the 

 leaf-cutting bee" (Proc. Essex inst., 

 vol. 4, 1S64. pp. 105-107) has pub- 

 lished some interesting observations 

 made on Megachile centunculat-is 

 Linn., a species common to Europe and 

 the northern parts of North America. 

 He says : — 



My attention was first called, on the ;6th of 

 June, to a female busily engaged in bringing 

 pieces of leaf to her cells which she was 

 building under a board on the roof of the 

 piazza, directly under my window. Nearly 

 the whole morning was occupied by the bee 

 in bringing pieces of a leaf from a rose-bush 

 growing about ten yards from her cells, return- 

 ing at intervals of a half minute to a minute, 

 with the pieces which she carried in such a 

 manner as not to impede her walking when 



she alighted near her hole. About noon she 

 had probably completed the cell upon which 

 she had been engaged, as during the after- 

 noon, she was occupied in bringing pollen, 

 preparatory to laying her single egg in the 

 cell. For about twenty days the bee con- 

 tinued at work, building new cells and 

 supplying them with pollen. At the end of 

 this time she had probably completed her 

 allotted task, as she was not seen again. 



On the 28th of July, upon removing the 

 board, it was found that the bee liad made 

 thirty cells, arranged in nine rows of unequal 

 length, some being slightly curved to adapt 

 them to the space under the board. The 

 longest row contained six cells, and was two 

 and three quarters inches in length. The 

 cells averaged about one half an inch in 

 length; the whole leaf structure being equal 

 to a length of fifteen inches. Upon making 

 an estimate of the pieces of leaf in this struc- 

 ture, it was ascertained that there must have 

 been at least a thousand pieces used. In 

 addition to the labor of making the cells, this 

 bee, unassisted in her duties, had to collect 

 the requisite amount of pollen (and honey.') 

 for each cell and lay her egg therein, when 

 completed. 



Mr. Putnam found the cells internally 

 to be hard and smooth owing to the 

 movements of the larvae ; thev meas- 

 ured .35 inch in length by .15 inch in 

 diameter. The full grown larvae spin 

 slight silken cocoons within which to 

 pupate. Imagos began emerging July 

 31 and continued during the first week 

 in August. 



This species is parasitized by Melit- 

 tobia megachilis Packard, and the eggs 

 of this parasite are supposed to harbor 

 the smallest Hymenopteron known, 

 Pterafomns PHtna)nii Pack. 



