876 Charles Paul Alexander 



valves may be very much reduced, as in Tipula serricauda. The ovi- 

 positor in Tanyptcra (fig. 131, b) is normal, but the terminal abdominal 

 segments are greatly narrowed and produce a saber-like appearance. 



sexual dimorphism 



Besides the differences between the two sexes in the shape of the 

 antennal segments, already discussed, there are many other structural 

 differences. In some species the eyes of the female are much smaller 

 than those of the male, and in the latter the eyes may be contiguous 

 (holoptic) or approximated. In species with elongated rostra, such as 

 in the genus Geranomyia, the rostrum of the female is often much 

 shorter than that of the male. The legs of the female are in some cases 

 shorter than those of the male. The wings of the females of many species 

 in widely separated tribes are often reduced so as to be incapable of 

 flight; in some forms (Empedomorpha) the stigma of the male is much 

 larger than that of the. female; in Tipula armatipennis of southern Brazil, 

 the wing of the male is amied with an acute spur abov-e the stigma; many 

 other species have the costal region strongly incrassated; in the genus 

 Peripheroptera, with the greatly enlarged cells before the arculus described 

 elsewhere, these cells arc much smaller in the female than in the male, 

 and the anal angle of the wing is more prominent. 



Color dimorphism is found in the species of Ctenophora and Tanyptera, 

 the specific hmits of which are very poorly understood at present. In 

 at least three eastern- American species of Tipula {Tipula fuliginosa, 

 T. annuliconiis, and T. taughannock) , the males are light yellow, while 

 the females are from dark brown to brownish black and appear to be 

 veiy different insects. 



As a rule the females are larger than their mates, but in some species 

 (Teucholabis, Eriocera longicornis, and others) the male sex is the larger. 



HAUNTS 



The various species of Tipulidae are, within rather broad limits, con- 

 fined to certain definite haunts or ecological situations. Some species are 

 very closely restricted by their habitat, while others occur in a great 

 diversity of situations. There is no crane-fly that can be called cosmo- 

 politan; Helohia hyhrida is nearly so, ranging, as it does, over most of 

 the New World, the Palaearctic region, and southward into the Oriental 



