1917.] 199 



abundance, the females were continually entering the burrow fully laden 

 and issuing from it unladen, so as to compare in numbers with those of 

 a weak nest of one of ovir common wasps. I do not think the Nomada 

 was more than one to ten of its host, and no S of the parasite nor yet 

 of the Andrena was seen to enter either of the burrows. The males of the 

 latter flew wildly round the bushes close to the burrows, rarely settling on 

 Mowers, generally in company with those of A. friminerana {auct. plur., 

 ace K.), which they greatly resemble on the wing. Occasionally a S of 

 tlie Nomada was seen with them, bvit the parasites mostly flew lower 

 al)out the bushes or over the herbage, occasionally settling on a bare 

 stone in the hot sunshine. Not a single example of these vagrant males, 

 either of host or ])arasite, was foimd beyond a radius of flfty yards from 

 the burrow, so that both insects were extremely local. 



On April 15th these species were at the height of their abundance 

 and both sexes were in beautiful condition, although many of the 

 hiicephala already carried great loads of pollen. My last inspection 

 was on June 18th, when 1 took one of my boys, who was away from 

 school on that date, to the locality, he being anxious to see the species 

 alive and their burrows. On that occasion the female Andrena was 

 much faded and neai'ly over, and only one Nomada was seen. Males 

 were quite over. I had some idea of digging out one of the nests to 

 study the mode of nidiflcation, but, unfortunatelj", two of the burrows 

 appeared to have been scratched out by some predaceous animal, and I 

 did not care to interfere with the remaining one. Possibly the common 

 L'utrance leads to some cavity in the rocky ground and the pollen-masses 

 are either deposited there or separate burrows start from that point. It 

 has been stated by a Continental writer that colonies of Halictus quadri- 

 vincfns are formed with a single common entrance, but I have seen 

 nf)thing of this kind with any British species of that genus that I have 

 examined. Certain Fossors, however, e. g. Crahro leucostoma and Pem- 

 p/ircdon Iiif///br/s, appear to form such colonies, though not as a regular 

 habit. Amongst the long-tongued bees some Meyachlle and Osmia 

 form their nests, several or many together, with a common entrance. 

 This may take place in the soil or in various other situations, e. g. pipes, 

 door-locks, etc., but in the latter cases the entrance is not the work of the 

 bee itself. It is curious that F. Smith and others, who for many years 

 had the large colony of A. hiicephala that used to exist at Hampstead 

 \inder observation, recorded no peculiarity in the habits. Possibly these 

 vary, as in the case of the Fossors mentioned above. It would be 

 interesting to know whether the allied A. ferox Sm. has similar habits, 

 as, if so, this might partly account for the infrequency with which this 

 widely-distributed species has been met with. 

 AiKj.^th, 1017. 



