134 HYMENOPTERA. 



beaten down and smoothed off by the bee. The other side of 

 the partition, forming the top of the cell, is flat and rough. 



At the time of opening the burrow, July 8th, the cells con- 

 tained nearly full-grown larvae, with some half developed. 

 They were feeding on the masses of pollen, which were as large 

 as a thick kidney-bean, and occupied nearly half the cell. Sa- 

 pyga repanda is parasitic in the cells of Xylocopa violacea of 

 Southern Europe. 



The habits and structure of the little Ceratina ally it closely 

 with Xylocopa, as it hollows out the stems of plants, and builds 

 in them its cylindrical cells. This bee is oblong in form, with 

 tridentate mandibles, and a short labrum. The maxillary palpi 

 are six-jointed, and the labial palpi are two-jointed. Ceratina 

 dupla Say is a common small bright-green smooth-bodied species, 

 which, in the middle of May, according to Dr. Harris' MS. notes, 

 tunnels out the stems of the elder or blackberiy, syringa, or any 

 other pithy shrub, excavating them often to a depth of six or 

 seven inches, and also, according to Mr. Haldcman (Harris 

 MS.), bores in Cocorus. She makes the walls just wide enough 

 to admit her body, and of a depth capable of holding three or 

 four, often five or six cells (Plate 4, Fig. 11). The finely built 

 cells, with their delicate silken walls, are cylindrical and nearly 

 square at each end, though the free end of the last cell is 

 rounded off. They are four and a half tenths of an inch long, 

 and a little over one-third as broad. The bee places them at 

 nearly equal distances apart, the slight interval between them 

 being filled in with dirt. 



Dr. T. W. Harris* states that, "May 15, 1832, one female 

 laid its eggs in the hollow of an aster-stalk. Three perfect in- 

 sects were disclosed from it July 28th." The observations of Mr. 

 Angus, who saw some bees making their cells, May 18th, also 

 confirms this account. The history of our little upholsterer is 

 thus cleared up. Late in the spring she builds her cells, fills 

 them with pollen, and lays one or more eggs upon each one. 

 Thus in about two months the insect completes its transforma- 

 tions ; within this period passing through the egg, the larval 

 and chrysalid states, and then, as a bee, living through the win- 

 ter. Its life thus spans one year. 



* According to a note hi MSS. deposited in the Library of the Boston Society of 

 Natural History. 



