1913] 
Burrill: Lake Michigan Swarms of Chironomids 
57 
before now forming a nearly spherical cloud, now stretching out 
cigar-shaped, now rising and falling near the earth, the swarms 
keeping close to the house on the lake side (east), a distance of 
about four rods from the edge of the 150 foot bluff. As noticed At 
various points along Day Avenue on the way from the street car 
to the bungalow, there were several such swarms composed of 
fewer individuals. From these swarms fell mating pairs and 
dozens of such pairs were rolling about on the ground. Females 
seemed to fly into the swarms of males, and pairs then fell out of 
the swarm as if unable to maintain their position in the air. Gen- 
erally these pairs would not separate very quickly. For example, 
two larger flies, a Stratiomyid (probably Sargus decorus) I had 
just rescued ftom a tub of rain water, and a Bibionid ( B . albi- 
pennis ) from a window screen, were placed in a roomy vial with 
a pair of these mating Chironomids, and there the two bigger 
flies tumbled over the mating pair several times and knocked 
them about before the midges became separated. 
POSITION OF DANCE INCONSTANT 
The evening and morning midge dances did not occur in exactly 
the same places as noted during four days, May 24 to 28. While 
other species of midges occasionally enter the swarms, the little, 
long, black midge already discussed remained predominant and 
controlled the position of the swarm except when momentary 
gusts of wind blew the whole mass out of place. A few evenings 
previous the larger swarm was just east of and a little lower than 
the gable end of the ridge pole and bulged lake wards with every 
slight draft of the westerly intermittent wind. Two nights later 
a swarm hovered about six feet lower than the previous position 
a point at the upper sash of the first story window and about a 
yard from it. On the morning of the 28th the chief swarm was 
above the porch roof and south-east of the house, a position about 
a rod from the window position last noted, but not above any 
prominent part of the house nor above any part different in 
color. These locations do not well coincide with the recently 
advanced theory (Radi. 1903, Untersuchungen liber den Photo- 
tropismus der Tiere., pp. 80-1 in contrast with p. 126), that the 
species avoid the direct rays of the sun, choosing the shady side 
