1916.] 213 



(i.e., lateralis E. S.) and A. hucephala on blackthorn blossom at Box 

 Hill on the same day. 



In some localities, e.g., in Monmouthshire, I have found A. praecox 

 in the utmost profusion, without any of its parasite, the latter being 

 much the rarer in England, and, so far as I know, not occurring in 

 the West. 



N. borealis Zett. All authors give A. clarhella K., as the host 

 of this species, Smith and Shuckard indeed give no other. Since their 

 time, however, it has been found also to parasitize A. ajncatci Zett. 

 I have myself recently taken a few examples on Dartmoor with the 

 latter, in places where no clarJcella have ever been met with. The 

 attack on two hosts, so dissimilar, is of great interest, and it would be 

 interesting, were it possible, to compare a long series of the parasite 

 from a locality, where only the one host is found, with those from 

 another place, where the other host occurs alone. 



N. flava Panz., though a very abundant insect in many localities, 

 still requires careful study in the field, as to the species it parasitizes. 

 It is certainly a common parasite of A. trlmmerana, but whether it 

 attacks A. nigroaenea also is not certain. Certainly A. trimmerana is 

 the usual host. As N. flava in one of its varieties approaches some- 

 what to JV^. signata, the parasite of A. fulva, and in another variety is 

 very similar to the la.rge form of ruficornis, which parasitizes the 

 same Andrena, it would be interesting, if it should prove that these 

 two varieties of flava were also attached to A. fulva ; but I have no 

 evidence that this is the case, and think that it is unlikely. 



N. r^iflcor7iis s.str., is generally, if not solely, the parasite of those 

 species of Andi-e^ia, which belong to the group of A. varians, exclusive 

 of A. inaecox and apicaia, both of which, as above mentioned, have 

 their own special forms, distinct from ruficornis proper. How far or 

 how constantly the varieties of ruficornis, which attack diiferent 

 species of the varians group, differ in the range of their variation I 

 have not the material necessary for a decision. I have read that the 

 form of ruficornis, which is pai'asitic on A. varians, is considered on 

 the Continent as the typical form, but I should think that this is 

 merely guess-work. I have before me three series of ruficornis of 

 which the host is known to me. One of these is from A. fulva, one 

 from A. amhigua (but this may have some from A. fucata mixed with 

 them) and the third from A. lapponica. In each of these cases the 

 examples of ruficornis appear to have at least a very distinctly different 



