BEES OF GREAT BRITAIN. 117 



ceding. The maxillary palpi six -jointed, nearly as long as the 

 apical lobe ; the basal joint minute, the second and third joints 

 of about equal length, the remainder gradually decreasing in 

 length, and each more slender than the preceding. The superior 

 wings have one marginal and three submarginal cells, the second 

 submarginal receiving the first, and the third the second recur- 

 rent nervure. Legs simple in both sexes. Abdomen : the apical 

 segment truncate at the apex in the females, acute in the 

 males. 



The bees belonging to this genus are popularly known by the 

 name of Wasp-bees, from their close resemblance in their gay 

 colouring to the smaller species of Vespida ; they are however 

 true bees, and constitute the most beautiful of all the genera 

 found in this country ; notwithstanding the generally received 

 history of their economy, we shall search in vain for much pre- 

 cise information. In the Entomological Magazine we learn that 

 they deposit their eggs in the nests of other bees at the time 

 when the working bees deposit theirs ; and that when hatched, 

 the larva being stronger and larger than the rightful possessor 

 of the cell, it consumes the food of its companion and starves 

 it to death : all this however is mere conjecture ; the larva of 

 these parasites must always be smaller than that of the working 

 bee, No one appears to know anything beyond the mere fact of 

 their entering the burrows of Andrenidce and Apida, except that 

 they are found in the cells of the working bees in their perfect 

 condition : it is most probable that they deposit on the provision 

 laid up by the working bee, that they close up the cell, and that 

 the working bee, finding an egg deposited, commences a fresh 

 cell for her own progeny. My reason for thinking it probable 

 that the parasite closes the cell, is that I have frequently captured 

 Nomadce and MelectcB with masses of clay attached to their pos- 

 terior tibiae ; and in the well-known genus of exotic parasitic bees, 

 Crocisa, specimens are of frequent occurrence which have masses 

 of clay or mixed earth on their tibiae ; this however requires, and 

 is deserving of, further investigation. I have found several of the 

 species in the cells of Andrenidce these will be mentioned under 

 the respective species. It is, however, necessary to record one 

 instance which throws some light upon the economy of the 

 genus. Some years ago, in the month of June, I met with a 

 large colony of Eucera longicornis, and observed great numbers 

 of Nomada sexfasciata flying about amongst the bees, and occa- 

 sionally entering into and issuing from their burrows. In the 

 beginning of April of the following year I visited the locality for 

 the purpose of obtaining males of the Nomada, as very few were 



