DIPTERA OF MINNESOTA. 



95 



that "probably three-fourths of the species offer well marked peculiari- 

 ties that distinguish the males at a glance.'.' In the American Naturalist 



Fig. 87 and 88. Psilof'odinus sipho, male and female. Lugger. 



for 1894 he describes the courtship of a species of Dolichopus, which 

 he observed. It is so interesting, as throwing some light on the 

 habits of this large family, and, possibly upon the use of the adornments 

 above mentioned, that we quote him in full : 



"I observed in September the maneuvers of the male in courting the 

 female. He v^^ould place himself directly in front of her, at a distance of about 

 half an inch, with his* face toward her. He would then rapidly vibrate his 

 wings, holding them horizontally, at right angles to the body, and at the same 

 time would give these fore feet an up-and-down motion, raising them simul- 

 taneously above the level of the head and bringing them down with a slight 

 force upon the ground, the movement recurring in a measured way in about 

 half a second. This he would continue for some ten seconds; then, rising on 

 the wing, he would swiftly make a small semicircle in the air and attempt to 

 alight upon the female. In the large number of cases that I observed, he was 

 always unsuccessful, the female hastily moving away a few inches, when the 

 male would usually alight before her and repeat the movements just described. 

 On account of the numbers engaged in this occupation on the same small 

 area, I could not be certain that the same male always attended upon a given 

 female; but there can be no doubt that the females are exceedingly slow to 

 accept the males, for I saw the above maneuver repeated hundreds of times 

 with the same result. 



"In company with the species just mentioned occurred considerable num- 

 bers of a species of Hygroceleuthus, which I have referred to (Kans. Univ. 

 Quarterly, II., 24) as a variety of H. crenatus, O. S. These were engaged in 



