96 DIPTERA OF MINNESOTA. 



a similar occupation. The male of this species has only plain tarsi, but diflfers 

 from the female in having the antennal joints longer, the first two with coarse 

 black hair, and the arista of the third short and heavily covered with black 

 pubescence; the face is also longer, the wings broader, and the cilia of the 



Fig. 89. Ornamented tarsus of a Dolichopod. Original. 



tegulae, instead of being coarse and chiefly black, are fine and white. The 

 male hovers in the air before the female at a distance of one or two inches 

 occasionally making a slight darting motion toward her. In this position the 

 peculiarities of his face and antennae are shown to the best advantage. The 

 breadth of the wings is probably an advantage only in facilitating this hovering 

 process, and the structure of the tegular cilia may possibly be accounted for 

 by supposing that it is simply in compensation for the increased growth of the 

 wings. This male, after hovering a few seconds, describes a semicircle in 

 flight and attempts to alight upon the female as in the foregoing species, and 

 with the same results. I observed the copulation only once, and then did not 

 see the preliminaries. 



Fig. 89a. Wing of Dolichopod. After Comstock. 



"In this connection the observations of Fr. Dahl (Zool. Anzeig., April, 

 1889) on another species of Dolichopus are of interest. I translate from a 

 quotation in an article by Dr. W. M. Wheeler (Proc. Wis. Nat. Hist. Soc, 

 April, 1889, p. 209), which mentions a somewhat similar habit in a gall-gnat 

 {Asynapta antennariae, Wheeler). 



" 'The male species of f^y, Dolichopus plumipes, possesses on first tarsal 

 joint of the middle legs a beautiful, regular fringe, the purpose of which is not 

 immediately perceptible, as the flattened hairs could not possibly serve to grasp 

 the female. I have now observed the pairing of these insects, and am con- 

 vinced that the structure serves as an actual ornament to the male, like the 

 highly developed tail-feathers, etc., of a male bird. The male came flying up, 

 and hovered for a time so close over the quietly resting female that the fringed 

 tarsi hung down immediately before her eyes. After some time copulation 

 was attempted, but the female at once showed unwillingness. Only after 

 repeated attempts did he succeed in gaining her acceptance,' " 



