340 
The Ohio Naturalist. 
[Vol.XI, No. 7 
Length 9.5-10 mm., width 4.5-5 mm., height about 4.5 mm. 
Color, Roman sepia, a little darker than the larva. The puparium 
is broadest a little back of the sixth larval segment, is nicely 
rounded in front, and tapers gradually to the last segment which 
remains somewhat flattened, especially at the sides. The cover- 
ing of small black bristles is retained and the black conical prom- 
inences become even more conspicuous owing to the inflation 
(Figs. 6, 7). The posterior breathing appendages are retained. 
The date of pupation was about the middle of October. Indoors 
the duration in the pupal stage was about 20 days. 
I have made no observations which would indicate that the 
larvae crawl far before changing to the pupae. I have found 
pupae on the under sides of the horizontal branches of the Syca- 
more not far from the colonies of plant lice among which they fed. 
The shining brown color together with the black, spiny, 
conical projections on the dorsal side give to the pupa of Didea 
fuscipes a characteristic appearance easily distinguished from 
that of the other Syrphidae I have seen. The pupae are protected 
by the indurated puparium and somewhat by the sheltered posi- 
tion on the bark taken up by the larvae. 
I have found the pupa late in November and it is probable 
that the fly passes the winter in this stage. 
The adults have been taken from the middle of May to the 
last of September. I have studied only the autumn generation 
of larvae. 
The adults emerge by bursting off a circular lid of the pupa 
case (Fig. 7). This is accomplished by expansion of the lower 
part of the face 
ADULT. 
9, a 71 . Length 11-15 mm. 
Description, slightly modified from Williston. Bull. U. S. 
Nat. Mus., No. 31, 89 (1886). Face yellow, with a small 
elongate brownish spot on the tubercle. Front yellow, with 
two brownish spots above the antennae, or, in the female, 
with an inverted Y-shaped brown stripe connected with the 
black of the upper part of the front. Eyes bare. Orbits 
thickly yellowish pollinose, posteriorly with a fringe of yellowish- 
whitish pile. Antennae black, the third joint at the base some- 
times reddish, elongate oval, obtusely pointed at the tip; arista 
reddish. Thorax shining greenish black, on the meso-, ptero-, and 
stemo-pleurae yellow, thickly covered with similar colored pollen 
and pile. Seuttelum light yellow, translucent. Wings grayish 
hyaline, the base before the humeral cross-vein and the stigma 
brown; the remainder of the sub-costal cell and the costal cell 
may be brownish; third vein rather deeply curved near the middle 
of the first posterior cell. Legs brown, the posterior tibiae and all 
the tarsi blackish; sometimes the legs are luteous, the base of 
