880 CHARLES PauL ALEXANDER 
G. diversa, Dicranomyia simulans, D. badia, D. stulta) practice a curious 
up-and-down bobbing while at rest or while feeding, their long’ slender legs 
acting as springs. 
Swarming and mating 
Swarming usually takes place during the early hours of twilight or 
in the late afternoon. The swarming of the Limnobiinae is a familiar 
performance. The number of individuals participating varies from 
two or three to a dozen or twenty in Rhabdomastix flava, Ula elegans, 
Limnophila brevifurca, L. ultima, and Epiphragma fascipennis, several 
hundreds in most species of Ormosia and Erioptera, and vast swarms 
in species of Trichocera and in Eriocera longicornis, in which many 
thousands of individuals are involved. In practically all cases the start 
of the swarm is the same. It begins with one or two individuals and is 
gradually augmented by the arrival of newcomers. Usually the flight is 
not far above the ground, that of the smaller species (as in the genera 
Ormosia, Limnophila, Dicranota, and Rhaphidolabis) taking place under 
the low branches of a tree or the inclined trunk of a fallen log. In Eriocera, 
however, mating usually takes place in the open, often over the broad 
expanse of a river or a stream. ‘The vertical height covered by the dance 
varies from a few/ inches in some species to many feet in Brachypremna 
dispellens, the “king of the dancing crane-flies.” Mating takes place 
during the swarming, and the united pair generally leaves the main body 
of the swarm and flies away to a resting place. 
The tipuline forms and some of the Limnobiinae (several species 
of Dicranomyia, species of Hexatoma, Tipula macrolabis, T. fragilis, 
T. fuliginosa, T. taughanneck, and others) seem to mate without the 
preparatory operati:xn of swarming, the males searching diligently and 
unceasingly for their mates, walking and fluttering about until they 
encounter the hiding female and then engaging in copulation. As stated 
by Needham (1908:215) in the case of Dicranomyia simulans, the males 
of this species seem to be very short-sighted and apparently unable to 
see their mates even when very close to them; they seem to rely mainly 
on the tactile nature of their long, filiform feet, which, the instant they 
come in contact with any part of the female, apprise the male of its 
proximity. 
