AUGUST 141 



that I am correct in identifying as a species of Simu- 

 lium the bloodthirsty swarms which rose from the 

 heather at every step on the banks of Beauly, no 

 epithet could be found less appropriate to their 

 conduct than ' harmless.' They were simply insatiable, 

 and in such clouds as half to blind one. Probably an 

 explanation is forthcoming in the fact that Miall's 

 observation was conducted in weedy Yorkshire streams, 

 wherein he found the larvse attached in countless 

 numbers to the leaves of submerged water-plants. 

 When he adds, ' I believe that the larvse found in 

 stony streams belong to a different species/ it appears 

 that the habits of the sand-flies which I encountered 

 on the Beauly, which, for the greater part of its course, 

 is a rushing torrent among cliffs and boulders, have 

 not as yet been submitted to scientific scrutiny. 



The question often presents itself Upon what do 

 blood-sucking gnats, midges and their kin feed when 

 there is no human being at hand to prey on ? To 

 this no decisive answer has ever been given. Mr. 

 David Sharp inclines to the view that it is an acquired 

 habit, confined, as aforesaid, to the female insects. 

 Probably food of any kind is not essential to the 

 welfare of these insects in the imago stage of existence, 

 any more than it is to a butterfly ; but just as a butter- 

 fly sucks honey on sunny days and fasts on rainy ones, so 

 Madame and Mademoiselle Midge suck the juices of 

 animals and succulent vegetable with equal avidity when 

 they get the chance. But why can't they do so with 

 decent regard for the comfort of their victims ? Why 

 should they inject some kind of irritant fluid when 

 they begin their meal ? The nature of that fluid has 



