1894,] Courtship Among the Flies. 35 
COURTSHIP AMONG THE FLIES. 
J. M. ALDRICH. 
The dipterous family Dolichopodidae perhaps surpasses all 
other families of animals in the variety and complexity of the 
sexual adornments of the males. These structures occur in 
some species in the tarsi, in others in the antennæ, face, wings, 
or other parts. Probably three-fourths of the species offer 
well-marked peculiarities which distinguish the male at a 
glance. 
In the genus Dolichopus, the males are usually provided 
with tarsal ornaments, usually on the fore limbs. A new 
species, to which the following remarks apply, has the fore 
tarsi in the male exceedingly elongated and slender, with the 
last joint in the shape of a comparatively large, oval, black 
disk. In none of the numerous other species known to me is 
the attenuation of the first three joints so great. The tarsi of 
the female are of the ordinary simple structure. 
This species is abundant about the edges of the streams, on 
the wet, bare earth, at Moscow, Idaho. I observed in Septem-: 
ber the maneuvers of the male in courting the female. He 
would 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 simultaneously 
above the level of the head and bringing them down with a 
slight foree 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 mov- 
away a few inches, when the male would usually alight before 
her and repeat the movements just described. On account of 
the numbers that were engaged in this occupation on the same 
small area, I could not be certain that the same male always 
1 Moscow, Idaho. 
