16 BEES OF GREAT BRITAIN. 



and indeed many circumstances tend to support such a supposi- 

 tion; they are usually found burrowing not only in similar 

 situations, but forming mixed colonies; the females of both 

 genera appear some time before the males, and in fact their 

 economy is alike. St.Fargeau places them amongst his division 

 of parasites, immediately following his exotic genus Rathymus, 

 with which they have not the slightest affinity ; their only resem- 

 blance being in the distribution of the colours, black and red. 

 The result of my observations leads to the conclusion that no 

 species of the Andrenida is parasitic. The only apparent sup- 

 port of the theory of their parasitism, is the absence of the 

 usual pollenigerous organs ; such however is also the case in 

 Prosopis, Ceratina, &c. In the year 1849 I discovered a mixed 

 colony of the Halictus abdominalis, Andrena nigro-cenea, Ha- 

 lictus morio, Sphecodes subquadratus and Sp. Geoffroyellus ; this 

 being at a short distance from my house, I had an opportunity 

 of frequently observing their economy ; my visits to the colony 

 were frequent, and I made close observations of the proceed- 

 ings of the bees ; yet notwithstanding, I could not in a single 

 instance detect the Sphecodes entering the burrows of Halictus ; 

 those into which the former bee entered were of a smaller dia- 

 meter than those of Halictus, in fact intermediate in size be- 

 tween the burrows of H. abdominalis and H. morio too small to 

 have admitted the female of abdominalis. These proceedings 

 were observed on several occasions : no males of any of the bees 

 were to be seen at this time, those of Andrena having disappeared 

 some time, and those of the Halicti not being developed. On 

 visiting the colony one cloudy morning, I was much delighted to 

 observe the head of one of the species of bees at the mouth of 

 most of the burrows the female Halicti at their own burrows, 

 and Sphecodes also at their own. The result of my observations 

 of this colony led me to believe, still more firmly, that Sphecodes 

 is not a parasite. Since the time when the above observations 

 were made, I have on several occasions detected Sphecodes 

 busily engaged in forming her burrow, a fact which I consider 

 conclusive of the correctness of the opinions above stated. 



1; Sphecodes gibbus. 



S. aterrimus, abdomine ferrugineo, basi apiceque nigris ; alis ni- 

 gricantibus. 



Sphex gibba, Linn. Faun. Suec. 413. 1658 ; Syst. Nat. i. 946. 33, 



Sf Cad. Mus. Linn. Soc. $ . 

 Nomada gibba, Rossi, Faun. Etrus. ii. 63. 816. 



Fabr. Ent. Syst. ii. 212. 59. 

 Apis rufa, Christ. Hym. 201. 1. 17. f. 12 ? . 



