194 HYMENOPTERA ACULEATA. 



number of alar hooks, the form of the sixth dorsal valve 

 aud the general puncturation are the chief distinguishing 

 characteristics. They frequent similar localities to Ilalichus, 

 and the question as to whether they are inquilines on the 

 hitter genus is still to a certain extent an open one. The 

 direct evidence in favour of it rests on many observations 

 that certain Spliecodes are always found with certain Ilalieti, 

 and are not found in localities where these Halicti are 

 absent. The evidence against it rests on the fact that 

 Sphecodes has more than once been seen making a burrow 

 for itself. Mr. R. C. L. Perkins's observations on these 

 points (E. M. M. xxv. p. 207) seem to me to go a long way 

 towards establishing the former of these positions, which I 

 tliiuk is strengthened by the very strong structural simi- 

 larity of the two genera and the exact similarity of their 

 habits, which are unlike those of any other solitary bees ; 

 the ? passes the winter in an impregnated state, and iu 

 the spring emerges and makes her cells and lays her eggs ; 

 about July or August the new males begin to emerge, and 

 the new females follow them in about a week or fortnight ; 

 after this the males may be found plentifully about flowers, 

 &c., and the majority of the females, after impregnation^ 

 burrow, or at any rate stay near their burrows, and wait 

 for warm spring weather to wake them up to work again. 

 There are at pi-esent fifteen known British species, but this 

 number may be yet increased, and the number of European 

 species is probably still quite uncertain. Like Halictus, it 

 is found all over the world. It is essential for the correct 

 determination of these insects to extract the genital arma- 

 ture of the (J, so that it shall be visible beyond the apex of 

 the abdominal segments, and also to draw out the apex of 

 the abdomen in the ? , so that the glabrous area of its apical 

 dorsal valve can be fully examined. Specimens not so 

 prepared are sometimes quite impossible to name. 



(8) 1. Larger species, posterior wings with 

 7-10 hooks. 



