784 CHARLES PAUL ALEXANDER 



of prominent black spots converging behind. Mandible stout, with a single powerful outer 

 tooth. Mentum bilobed, anterior margin not comblike. Color of body, rusty red. 



p upa ,~ Right pronotal breathing horn very elongate; the left very small and short, 

 subdegenerate. Fore tarsi overlying middle tarsi. Tubercles on abdomen very long, located 

 on broad transverse bands of chitin, each tubercle with a star of four or five spines surrounding 

 the apex, which bears a long seta. 



The genus Bittacomorpha, as here restricted, includes but two species - 

 the genotype, B. clavipes (Fabr.), and B. occidentalis Aid. of western 

 America, concerning the biology of which nothing has been recorded. 

 The literature on the immature stages of Bittacomorpha clavipes is sum- 

 marized under the family account (page 773). 



Bit'acomorpha clavipes (Fabr.) 



1781 Tipula clavipes Fabr. Spec. Ins., vol. 2, p. 404. 



1835 Bittacomorpha clavipes Westw. London and Edinburgh Phil. Mag., vol. 6, p. 281. 



Bittacomorpha clavipes, the " phantom crane-fly," is a common and 

 widely distributed species thruout North America east of the Rockies. 

 It is easily recognized by the black-and-white-banded legs, with their 

 conspicuously enlarged and swollen metatarsi. The species is very 

 characteristic of alder swamps and the wet margins of ponds. While in 

 copulation the insects often fly, the female ahead, the male trailing on 

 behind like the tail of a kite. When they alight on a plant stem, the 

 female is invariably uppermost, the male often hanging free with none 

 of its feet on a support. The swollen metatarsi are almost completely 

 filled by the tracheae, and these serve to buoy the insects as they drift 

 about in the wind. Brues (1900) describes these peculiar tracheal dilations 

 in detail. He says, in part: 



When flying, Bittacomorpha uses the wings scarcely at all, relying in great measure upon 

 wind currents for transportation. The legs are exceedingly light, as the exoskeleton is thin 

 and delicate, and encloses practically no tissue which can serve to increase their weight. 



In a letter from Dr. J. G. Needham, dated September 27, 1917, valuable 

 data on this habit of drifting are furnished, as follows: 



Yesterday while crossing the Fall Creek bridge near my home on Cornell Heights, I made an 

 observation on Bittacomorpha that interested me greatly. A breeze was blowing up the gorge, 

 and on the breeze a Bittacomorpha was drifting rapidly upward in the usual flight attitude, 

 with broadly outspread legs, the swollen metatarsi hanging vertically, all phantom-like in 

 slenderness and in strongly contrasting black and white. It came up from below the level 

 of the rail, swept past within two feet of my face, and passed on upward with the breeze until 

 lost to view, perhaps 100 feet higher than the bridge, and much farther upstream. Since 



