1970] 
Eberhard — Fungus Gnats 
373 
About an hour after the collar was completed, the body contractions, 
still accompanied by movements of the head, had decreased in ampli- 
tude and slowed to about one every seven minutes. 
The contractions and subsequent changes in body form apparently 
follow construction of the pupal line and collar regardless of the 
larvas situation. One larva fell off its line as it constructed a 
collar, and although it began to lay a trail of silk soon after it 
landed, its anterior end was swollen and it was nearly immobile 30 
minutes later. 
Although most pupae found in nature were under or near sites 
where larvae had apparantly fed, the positions of some pupae sug- 
gested that larvae sometimes moved several centimeters from their 
feeding sites before pupating. In one case, seven of eight pupae 
found on a fallen beech tree were under bare bark at the bottom- 
most surface of the log, several centimeters from the nearest fungal 
sporophores (brackets on the side of the log). Pupae were also 
usually oriented so that their longitudinal axes were nearly parallel 
to the longitudinal axes of the logs they were under. The axes of 
17 of 21 pupae were more nearly parallel than perpendicular to 
the axes of the logs they were under. The cues used to achieve 
these orientations and the functions of the positioning are not 
known. 
Larvae often pupated soon after being brought into the laboratory, 
and it appeared that cues from the environment may sometimes 
induce them to pupate prematurely. In one typical case, 24 bracket 
fungus sporophores inhabited by larvae were removed from beech 
trees and pinned to cardboard boxes in the laboratory. Within two 
days the sporophores became noticeably drier, and eight of the 
largest larvae constructed pupal lines and pupated. None of the 
other larvae pupated, and all except two which were on surfaces 
particularly well sheltered from air movement were dry and dead 
in the midst of their sheets after five more days. On the other 
hand, some larvae kept on portions of sporophores in a cool (about 
I5°C) and moist environment in captivity only pupated after more 
than a week. Results like these suggested that once a larva reaches 
a certain size or maturity, it will pupate if its food source dries up. 
Pupation 
Larvae remained suspended for about 24 hours before they pupated. 
At the end of this period, segments 1 and 2 swelled even more, so 
that the line dividing them became less distinct and the head capsule 
was nearly completely engulfed (Fig. 5 c, d). Hints of ridges also 
