26 THE CANADIAN ENTOMOLOGIST, 



6-rayed. In H. aureostriata the upper epistomal Iiair is usually single, 

 and the compound hair of the dorsal group on the terminal segment is 

 io-i2-rayed. The most notable differences are to be observed in the anal 

 gills, those oi H. incequalis being broadly lanceolate and pigmented, the 

 lower pair only one-half the length of the upper pair, which are one-third 

 the length of the longest hairs of the ventral hair group, while in H. 

 aureostriata they are nearly equal in size, narrow, slender and transparent, 

 and about as long as the hairs of the ventral tuft. The larvae collected 

 from hollow trees (chiefly Anona palustris L.) by the seashore, Kingston, 

 have long, slender, pale red bodies, covered with rayed hairs; a pair of 

 large air vessels in the thorax are seen as two conspicuous silvery spots. 

 The females are troublesome blood-suckers in the woods. Length of 

 adult, 2.5 mm. 



NOTES ON THE SWARMING OF A SPECIES OF CRANE FLY. 



BY CHAS. N. AINSLIE, WASHINGTON, D. C. 



The swarming habits of various families of flies, notably the Chirono- 

 mida? and Culicidce, have been known to the world probably for centuries, 

 since even unscientific people must have often been interested in the 

 phenomenon, perhaps, indeed, alarmed at it, so prodigious have sometimes 

 been the numbers of flies involved in these gatherings. .Accounts of 

 extraordinary swarms have been current in print for more than a hundred 

 years, but these stories deal for the most part with the size and actions of 

 the mass of flies, and rarely attempt an adequate explanation of the peculiar 

 gathering, from the view-point of the individual insect. A few species 

 of rhe TipulidtB have been noted as celebrating the same sort of air dance 

 as the smaller forms, but I have been able to find nothing in print that 

 describes in detail the mysterious performance. Having been fortunate 

 enough recently to witness and study this feature of the life-history of one 

 species of the Tipulidse, Trichocera bimacula, I venture to record the notes 

 made at the time, in the hope that some more competent observer may 

 write a more complete story than is possible for me. 



Nov. 2nd, 1906, was a clear, cool day, with a fresh northwest breeze. 

 Toward sundown the wind died away to an occasional, hardly-perceptible 

 breath, and the mercury fell to a point where it was quite chilly, perhaps 

 to between 45 and 50 degrees above zero, Fahr. The writer chanced to 

 be returning to Washington from Arlington on foot, and the way led along 

 the steam car track, which at one point skirts the bank of the Potomac, 



January, 1907 



