British Hymenoptera. 229 



recognisable. From the nature of these variations it 

 would appear probable that the genital organs are in 

 some way injured by the parasite while the insect is in 

 the larval state. Up to the present time as many as five 

 so-called species have existed in our list whose characters 

 depend entirely, as far as I can see, on the effects of 

 stylopisation, viz., Mou.ffetella, Kirby, = atriceps $ ; pi- 

 cipes, Kirby, and picicorais, Kirby, both of which = 

 Trimmerana <? and ? ; Aprilina, Sm.ith, ==nigro-(enea <? ; 

 and convexiuscnla, \\.,=.AfzelieUa. 



There can be, I think, little doubt that many of our 

 species are double-brooded, the first brood appearing 

 about the end of March or in April, the second appearing 

 in July or August ; in some cases the two broods resemble 

 one another almost exactly, as in pilipes, thoracica, 

 fidvienis, and Afziella ; in others the males are pretty 

 easily distinguishable by various characters of colour, 

 pubescence, &c. ; whereas the females are almost exactly 

 alike. This difference in the males has caused entomo- 

 logists to consider the two broods as representing two 

 distinct species; ih.u^, himaculataB,ndidecorata; Givynana 

 and hicolor ; parrula and iidmdida ; dorsata and comhinata : 

 all, I believe, belong to species which have a spring and 

 autumn brood ; and this view, I think, receives support 

 from the fact that in the localities where the spring form 

 occurs the autumn form is found also ; that there should 

 be a slight difference between the tw^o broods does not 

 seem to be unnatural, as the food supplied to the larvae 

 in each case must almost necessarily be different ; as a 

 rule, the species which frequent the sallow in the early 

 spring frequent the flowers of Enbus in the summer. 



The bees of this genus, as a rule, form colonies of 

 greater or less extent either in hedge-banks or pathways, 

 or other exposed surfaces of earth ; and consequently, in 

 most cases, if one specimen is met with, others are sure 

 to be found near the same spot ; the males, however, do 

 not always occur with the females : for instance, the 

 female of some species may be abundant on the flowers 

 of a sallow-bush ; the males very likely will be seen 

 coursing up and down the hedge under the sallow, or just 

 above the ground if their colony is close by ; the males 

 also seem to come out earlier and stay out later than the 

 females, and they may often be found flying about as late 

 as 5 or 6 o'clock. Mr. F. Smith has given such an 

 excellent account of the general habits, &c., of these 



