XIV. INSECT VISITORS ACULEATE HYMENOPTERA. 



I have much doubt as to wind-fertilised flowers. I have seen 

 insects on Grasses, Sedges, Plantago, Thalictrum, and of course on 

 Willows. It is obvious that if two flowers of Thalictrum are separated 

 by five feet, the chance is one to thirty that a pollen grain should go 

 within a foot of the right direction, and the wind and gravitation pro- 

 bably diminish the probability to an indefinitely small extent. If an 

 insect is, for any reason, on one, the chances are ten to one that it will 

 go to the next visible flower. 



I should, if I had drawn this introduction out at the beginning of 

 my work, have added tables showing the proportions of Hymenoptera, 

 Diptera, etc., but now this does not seem to be advisable. No one 

 would have supposed that a plant which is visited by one butterfly, four 

 species of humble bee, and two Syrphids was anything but a red or 

 purple Corolliflor, whereas these were all caught on the common 

 bramble, Rubus fruticosus* I am, however (vide Labiatae and Caryo- 

 phylleae), firmly convinced that the shape of every flower as well as the 

 modes of dehiscence, general arrangement, and so on, are entirely suited 

 to the average insect visitor of the particular species. In most cases the 

 corolla is nearly an exact mould of the shape and motions of the head 

 and proboscis of the average visitor ; it is very rarely the shape of its 

 head at rest. In fact, granted growth of the corolla and the obvious 

 modifications due to mechanical strains and stresses, most flowers seem 

 to have suited themselves exactly to these shapes and motions, like a fox- 

 glove to a humble bee or an old glove to its wearer's thumb. 



Much as I should like to uphold Professor Henslow's theories as 

 to the exact effect of probing in stimulating the flow of honey and hairs, 

 the subject does not seem to me proved, and scarcely to be proved, 

 without exceedingly delicate and difficult experiments. 



It is not too much to say that the knowledge of British Hymenoptera, 

 and particularly Diptera, is disgracefully behind that of British Botany. 

 I have been most fortunate, however, in obtaining the invaluable assist- 

 ance of Mr Robert Service for the former and of Mr E. Brunetti for the 

 latter. These gentlemen have named all the insects cited under my 

 name, that of Misses Hannay, Miss Taylor, or Mr R. Armstrong, and I 

 have to sincerely thank them for this. 



THE ACULEATE HYMENOPTERA OF MID-SOLWAY. 

 BY ROBERT SERVICE. 



Amongst all the vast multitudes of the Insect tribes, I think it will 

 be generally conceded that in variety of habits, in the high intelligence 

 displayed in their social intercourse, and in beauty of form and colour- 

 ing, the Aculeate Hymenoptera stand unrivalled. Unfortunately, with 



* This flowers when there are practically no competitors, 



