46 BEES OF GREAT BRITAIN. 



cessary to be employed in effecting the deposit of their eggs in 

 the working bees' nests, that the parasites should bear a close 

 resemblance to the bees upon which they are parasitic : some 

 instances may undoubtedly be advanced, as Apathus and Bombus, 

 and also in the different species of Volucella which infest the nests 

 of humble-bees, but amongst the solitary bees no such resem- 

 blance is required to aid in any necessary deception. It may 

 be remarked, that the two cases are not analogous : this is true ; 

 and I am not prepared to say that in the case of the Bombi and 

 their enemies, it may not be necessary, but as regards solitary 

 bees it certainly is not ; colonies of Andrenidce and their para- 

 sites mingle together in perfect harmony, issuing from and en- 

 tering into the burrows indiscriminately. I have on several 

 occasions watched with much enjoyment a large colony of Eucera 

 longicornis, the males occasionally darting forwards with great 

 velocity, then turning sharply round, and as it were swimming 

 in circles close to the ground, then darting off again and again 

 in an unceasing round of sportive enjoyment ; their industrious 

 partners, whose whole existence appears to be bound up in one 

 unceasing round of labour, would occasionally return home laden 

 with food for their young progeny. Sometimes it would happen 

 that a Nomada had previously entered her nest; when such proved 

 to be the case, she would issue from it, and flying off to a short 

 distance wait patiently until the parasite came forth, when she 

 would re-enter and deposit her burden. It will be observed, 

 in this instance, that between Eucera and Nomada no resem- 

 blance exists in general appearance, one being several times 

 larger than the other, and covered with pubescence of a sombre 

 colour ; whereas the parasite is a gaily-coloured insect, destitute 

 of pubescence, and readily observed from the brightness of its 

 colouring. To some extent, I have observed that a constant 

 connexion between certain species exists, and I have never met 

 with some species of these parasites except in connection with 

 certain species of Andrena ; but there are others, as Nomada 

 ruficornis, succincta, alternata and Lathburiana, which infest the 

 nests of several species of Andrena indiscriminately ; the species 

 are, A. tibialis, Trimmer ana, Afzeliella andfulva ; but the fol- 

 lowing I have never observed, except connected as follows : 

 Nomada later alls and A. longipes, N. baccata and A. argentata, 

 N. borealis and A. Clarkella, N. Germanica and A. fulvescens, 

 and, lastly, N. sexfasciata and Eucera longicornis. Much 

 further investigation is still necessary before we can arrive at 

 a knowledge of the real nature of the connexion which exists 

 between the bees and their parasites. It has been supposed 

 that the parasitic larva is hatched sooner than that of the 

 rightful owner of the nest, and that it consequently consumes 



