i PARASITIC BEES DENUDATAE 31 



r;ir'. "\Vliy then should they attack the creatures ? Provided the 

 parasites do not interfere in any unmannerly way with the hosts 

 and their work, there is no reason why the latter should resent 

 their presence. The wild bee that seals up its cell when it has 

 laid an egg therein, and then leaves it for ever, has no conception 

 of the form of its progeny ; never in the history of the race of the 

 Andrena has a larva seen a perfect insect and survived thereafter, 

 never has a perfect Insect seen a larva. There is no reason what- 

 ever for believing that these Insects have the least conception of 

 their own metamorphosis, and how then should they have any 

 idea of the metamorphosis of the parasite ? If the Andrena found 

 in the pollen the egg of a parasitic Nomada, it could of course 

 easily remove the egg ; but the Andrena has no conception 

 that the presence of the egg ensures the death of its own 

 offspring and though the egg be that of an enemy to its race, 

 why should it resent the fact ? Is it not clear that the race has 

 always maintained itself notwithstanding the enemy ? Nature has 

 brought about that both host and parasite should successfully 

 co-exist ; and each individual of each species lives, not for itself, 

 but for the continuance of the species ; that continuance is pro- 

 vided for by the relative fecundities of host and guest. Why 

 then should the Andrena feel 

 alarm ? If the species of Nomada 

 attack the species of Andrena too 

 much it brings about the de- 

 struction of its own species 

 more certainly than that of tho 

 Andrena. 



Such extremely friendly rela- 

 tions do not, however, exist be- 

 tween all the parasitic bees and 



r FIG. 16. Melecta luctuosa ?. Britain. 



their hosts. Friese says that, so 



far as he has been able to observe, the relations between the two 

 are not in general friendly. He states that marauders of the 

 genera Melecta and Coelioxys seek to get out of the way when 

 they see the pollen-laden host coming home. But he does not 

 appear to have noted any other evidence of mistrust between the 

 two, and it is somewhat doubtful whether this act can properly 

 be interpreted as indicating fear, for bees, as well as other 

 animals, when engaged in work find it annoying to be interfered 



