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Bulletin Wisconsin Natural History Society. [Vol. 10, Nos. 3-4. 
of the moving horses and later, during the bustle of camp life. 
On this point, Miall & Hammond quote interesting observations 
on alar, spiracular and other noises of midges and flies (M. & H. 
1900, 96-9 and 183-4) with which I was not familiar at the time 
of my note-taking—views which have since been disputed and 
limited by Pemberton (1911, 117) to two forms of alar sound. 
His tests suggest De Geer’s (Kirby & Spence, 1858, 487), who 
cut off a Tipulid’s wing in part, only to find the fly still buzzing; 
but on eliminating the whole organ, the buzz ceased. “The fric¬ 
tion of the base of the wings against the thorax seems to be the 
sole cause of the alarming buzz of the gnat as well as that of other 
Dipteral’ (ib. p. 488). 
Thus the sound has been traced to the wings only. No obser¬ 
vation of any other midge species has recorded so audible a buzz¬ 
ing as that made by plnmosus, though Johannsen (letter of Jan. 
4, 1912) writes me: “All of those with which I am familiar pro¬ 
duce the humming noise when sufficiently abundant and produce 
specks.” Though unacquainted with most of the 800 species (Jo¬ 
hannsen 1908, 76) known, I am sure that many compact swarms 
of a dozen smaller species by the lake near Milwaukee produce 
barely audible buzzing so far as could be detected at the distance 
of a dozen feet or so. 
In Prof. Williston’s Manual of the North American Diptera 
{1908, 111; quoted by Comstock 1910, 441; Howard 1908, hi; 
Johannsen, 1905, 77 ; Washburn, 1905, 52) so nearly similar 
swarms are mentioned that I propose the question whether Wil¬ 
liston’s midges could have been the same species. He says 
■“these midges are often seen, especially in the early spring or 
in the autumn, in immense swarms, dancing in the air, and have 
doubtless in many cases given rise to exaggerated stories of mos¬ 
quitoes. Over meadows in the Rocky Mountains the writer has 
seen them rise at nightfall in the most incredible numbers, pro¬ 
ducing noise like that of a distant waterfall, and audible for a 
considerable distance.” In a letter of Jan. 22, 1912, he gives the 
basis for this statement as “in May or June, 1878, at Lake Como, 
Wyoming. I can remember only that the species was a very large 
one [C. plumosus is largest], and how very distinct the noise was 
ihev made. The railroad men called them ‘skeeters,’ but I demon- 
