1913] 
Burrill: Lake Michigan Swarms of Chironomids 
63 
the competition for females is not great nor hostile despite the 
early abundance of males. 
To show the succession of Dipteron mating times, note that 
spotted-winged Tipulids were having a dance swarm of their own 
east of the house, at twilight, May 28. One pair was seen grap- 
pling each other as if in mortal combat (figured long ago in 
Reaumur’s Mem. 1737). I cannot add anything to Ainslee’s ac- 
count (ib. p. 27) of the dance except that the dance of this species 
was not so rapid as I judge he intends to convey in the statement, 
“a look through the swarm at an object beyond gave the former 
effect of whirling atoms and rapid motion.” Something of this 
effect is caused at times by the Chironomid dance, rhythmical in 
part, though the rhythmical pendulous figure-of-eight flight, faster 
than a pendulum, which Radi ascribes to the “Miicken” (Culicids 
supposedly Radi. 1901. Untersuchungen liber die Lichtreac- 
tionen der Arthropoden. Pfluger’s Arch. f. Phys. 87, 418-466), 
was not distinguished. 
DURATION OF FLIGHT AND RESTING HABITS 
Diurnal. The midges swarm an hour or two in the early morn- 
ing sunlight, then mostly quit flying and rest on available objects. 
The number flying before sunset varied daily, but an hour of 
dusk after sunset seemed to satisfy the swarming activity. In 
a recent paper on August swarms of C. plumosus, the record is 
made of midges flying to some extent throughout a cloudy day. 
It seems that even at the height of swarming each day, a major- 
ity of all the midges present are perching, some on the grass, on 
the underside of tree leaves, on the tree trunks and about the 
house on the clapboards, but especially on the porch screen, at 
the edges of which hundreds become enmeshed in the many orb 
spider webs. Of the trees, the majority roost on the underside 
of the leaves of silver maples, the trees nearest the lake (southeast 
and north of the house) being completely dotted with them, while 
few were to be found in the trees in the main grove west of the 
house. This daytime roost on foliage was carefully noted again 
June 2, 1912, at Madison. 
Nocturnal. My notes would have been full had I appreciated 
at the time the need of studying swarm duration. E. L. Taschen- 
