[September 
380 Psyche 
The only other mycetophilid species in which the larvae have been 
described pupating while hanging on threads in exposed places are 
Arachnocampa luminosa (Hudson 1950, Richards i960), and Speo- 
lepta leptogaster (Edwards 1924). Competition between males for 
female pupae has been recorded in A. luminosa. Males of this 
species commonly rest on female pupae, and at least in some situa- 
tions where there are dense populations, there are often several males 
clinging to a female pupa which is about to produce an adult 
(Richards i960). In contrast to L. subcaeruleus and L. bifasciatus , 
which probably use tactile or chemical cues to discriminate mature 
female pupae from others, A. luminosa males probably use vision: 
female pupae luminesce when touched, and glow especially brightly 
when the adult is about to emerge (Richards i960). Emerging 
adults of this species sometimes hang from the pupal cuticle by the 
tips of their abdomens for several hours (Hudson 1950), and may 
use the same mechanism to support themselves as the species in this 
study. 
There is probably selection in Lepto?norphus bifasciatus and L. 
subcaeruleus favoring males which are able to find, recognize, and 
hold mature female pupae, and also selection favoring females which 
pupate at easily located sites. Males which are larger, and thus 
perhaps more successful in fights, and which copulate long enough 
to insure the female is fully sclerotized and able to avoid the advances 
of other males might also be favored. These types of selection 
probably do not occur in many other Mycetophilidae, since most of 
the genera in the subfamilies Ditomyiinae, Bolitophilinae, Diado- 
cidiinae, Ceroplatinae, and Mycetophilinae pupate within fungi, 
under ground, or in cocoons in cracks (Edwards 1924, Mad war 
1937). The adults of at least some species, including Phronia sp. 
and Mycetophila sp. (Colyer and Hammond 1951) form swarms 
where mating may occur. 
Summary 
The larvae of Leptomorphus bifasciatus and L. subcaeruleus live 
on sheets of silk which they build under fungal sporophores, and 
apparently subsist on fungal spores caught in these sheets. Pupation 
occurs while the animal is suspended on a line constructed by the 
larva, and involves discarding the last two and one half segments 
of the larval body, but possibly not the larval cuticle. Adult males 
search for pupae, and rest on female pupae which are about to pro- 
duce adults. There is brisk competition between males for such 
pupae. The selective advantages of some of these habits are dis- 
