CASES OF ADAPTATION 157 



— which Mr. Seebohm tells us are an especially large kind 

 with bodies a third of an inch long — and the equal myriads 

 of their larvse in every little pond or water-hole, as well as 

 quantities of larger worms and larva'. The extreme discom- 

 forts as well as the cost of a journey to these far northern 

 lands are so great that very few bird- or insect-collectors vi>ir 

 them, and it is not easy to obtain direct and accurate obser- 

 vations as to the actual part played by the myriad swarms of 

 mosquitoes in attracting birds from almost every part of tlio 

 northern hemisphere to go and breed there. Mr. H. 3^]. 

 Dresser, who has made a special study of Palnearctic birds and 

 their eggs, has, however, obtained for me some very interesting 

 information. He writes: 



" Colonel Feilden tells me that the young of the knot are fed 

 chiefly on the larvae of mosquitoes." 



He has also sent me a copy of the following interesting letter 

 from an American ornithological correspondent, Mr. E. T. 

 Seton : — 



" In reply to your recent favour I beg to say, that, in my 

 forthcoming book on a canoe journey of 2000 miles which I made 

 to the Arctic regions in 1907, I am setting forth at great length the 

 numbers, virulence, and distribution of the mosquitoes, together 

 with observations on those creatures which are immune from their 

 attacks. ... I should say that the night-hawk (Chordeiles 

 virginianus) is the most active enemy of this insect, feeding on it 

 during the whole season. On one occasion T took over 100 

 mosquitoes from the throat of one of these night-hawks, that was 

 carrying them home to feed its young. Many similar observations 

 have been recorded. Next in importance would come the broad- 

 billed flycatchers of the American group Tyrannidae, and the more 

 abundant though smaller species of the Mniotiltidse. All of these 

 I have seen feeding on the adult mosquitoes. Doubtless all of our 

 thrushes do the same, although I do not recall any positive records. 

 We are very safe, I take it, in cataloguing all of our small birds 

 as enemies of the mosquitoes in the adult form. The various 

 small wading birds, and the small ducks and grebes, are believed 



