1913] 
Burrill: Lake Michigan Swarms of Chironomids 
53 
fair inference, then, that midges began to emerge before May 5 
in this cold, lake-governed latitude. May 21 to 23 was a period 
of rainy and foggy weather when none of these insects were in 
evidence, there being three such periods in May alone. 
Weather quickly affects the swarms, as this storm shows, and 
so does cold alone, say below 65° F. On the very cold afternoon 
of May 25, the midge swarms were nearly discontinued. Few 
flies were in the air at sunset, but hundreds of them were perched 
on the porch screens, seven pairs of copulating Chironomids being 
taken there. May 26 the weather was unfavorable and on the 
morning of May 27 I noted the midges resting mostly on the 
porch screen though a few tried flight close in the lee of it. During 
this period only two or three each of mosquitoes, Pimplinae, and 
Stoneflies, could be found, so the midges easily out-numbered 
other species. Even so, the coming of warmer weather by the 
evening of the 27th coaxed out a larger variety of midges than 
ever. Likewise, certain spotted-winged Tipulids, always few com- 
pared with midges, were noted in larger numbers than ever after 
the storms of May 23 and 27. 
May 29, a high wind which continued on the 30th; interfered 
with flying, so that delicate midges could not keep to their wings, 
while the cold temperature probably inhibited flight. The cold 
spell culminated on the 2d of June in a storm at a temperature 
of 36° F. that nothing but a Tabanid ( T . lasiophthalmus ) could 
withstand. The morning of June 3 was much warmer and 
seven supposedly different species of Chironomids were captured 
on the porch screen. These insects were very few in numbers 
during the continued cold to the evening of June 5, when a few 
more midges appeared, and the next evening, June 6, there seemed 
to be more midge flies on the porch screen than on any previous 
night. 
Dr. Asa Fitch records a New York forest swarm of C. nivori- 
undus as early as April 27, 1846 (1847, May. Winter Insects of 
Eastern New York. Am. Jour. Agri. Sci. V. 272-284). Kirby 
and Spence say (1858, An Introd. to Ent. 7th ed., p. 60), when 
speaking of both the mosquitoes and the midges, the “ Tipulariae 
of Latreille seem endowed with the privilege of resisting any 
degree of cold, and of bearing any degree of heat. In Lapland 
their numbers are so prodigious as to be compared to a flight of 
