STRAY NOTES ON ACULEATES. 151 



The males of some of the Aculeates are very quarrelsome. 

 I have seen a pair of Pompilus gibbus fight furiously for the 

 possession of a female which was present, and, on examining 

 them, have found that they had both suffered severely ; indeed, 

 the smaller of the two had no wings left, only the remnants of 

 nervures. 



I have seen the males of Mellinus arvensis, when cruising up 

 and down in front of the burrows of their females, seize each 

 other and, fighting fiercely, roll down the bank together. The 

 most combative of our Aculeates is, I think, Andrena tviikella. 

 I have often seen the males fight with each other in a most 

 determined manner. But they do not confine their quarrels to 

 those of their own race. I once saw a large female of Bombus 

 terrestris struggling on the ground, buzzing, and trying to get 

 away from something that held her, I found a male of A. tvii- 

 kella had seized her by the hind leg, and refused to let go, until 

 I captured them both. She was able to crawl about, but could 

 not ±iy away with her antagonist holding on, and did not appear 

 to offer any resistance. I put the angry Andrena into a bottle 

 which already contained a worker of Vespa vulgaris, thinking he 

 would soon have the tables turned on him, but he unhesitatingly 

 attacked the wasp, which, to my surprise, seemed quite afraid 

 of him, and disposed to keep out of his way, and he renewed 

 the attack every time the wasp came near him, and drove it off. 

 I cannot help thinking that this wasp was timid from finding 

 himself in the bottle, but that does not detract from the valour 

 displayed by the little Andrena. 



The males of Bombus sometimes quarrel among themselves, 

 and I have seen those of B. lapidarius fighting on the ground, 

 and tumbling over each other like two dogs, although I could 

 not see any female in the neighbourhood. Also when they are 

 presumably seeking the females, they often fly up and down a 

 hedge on a hot day, and will attack any one who passes near 

 them. In this way I have been persistently attacked by males 

 of B. agrorum and B. terrestris, the latter even striking my hat 

 as they dashed at me. 



I saw a fierce battle near Caesar's camp at Folkestone, 

 between four large females of B. lapidarius. Three of them 

 were on the ground when I first saw them, and the fourth came 

 to join in the fight while I was looking on. At first I thought 

 they must be males fighting for a female, but this was certainly 

 not the case. Then I thought perhaps it was a contest be- 

 tween Bombus and Psithyrus, but they were undoubtedly all 

 B. lapidarius. This is contrary to all my former experience. 

 Generally, the females of the social Hymenoptera are rather 

 gentle outside their nest. But these were fightnig on the open 

 ground, on the grass. 



I once watched a bank where many small solitary bees had 



