33 8 
The Ohio Naturalist. 
[Vol. XI, No. 7, 
dorsal line crown the summits of prominent conical projections 
which, like the rest of the dorsum, are close-set with short radiating 
black bristles. The second of these projections from the middle 
line on each side is about one-third as large as the first and situated 
on the succeeding fold. These transverse folds are continued 
laterally into distinct Y-shaped prominences which with those of 
other segments form a zig-zag longitudinal carina along each side 
of the body. The third spine from the middle-line on each side 
is situated at the apex of this V ; the fourth at the apex of a sim- 
ilar, underlying lateral cone or V; in front of which a small vent- 
rally-projecting fold forms two smaller spiny prominences bear- 
ing the fifth and sixth bristles. These form the lateral borders of 
the larva and give to it a very irregular outline of sharp angular 
projections. 
On the ventral part of the first segment are situated the mouth- 
parts and dorsal to these the antennae. The mouth-parts consist 
of two jaw-like pieces working longitudinally and at the sides of 
these three pairs of mouth-hooks adapted to work transversely 
(Fig. 3.) The jaws are continued internally into a tube-like 
oesophagus or gullet. All the parts are black and firmly chitinised. 
The antennae are very small consisting of a single fleshy joint 
with two minute rounded segments side by side at its apex. 
Surrounding these parts are a dozen or more small sensory papillae. 
In the middle of the third segment is a pair of anterior spiracles. 
These are light brown, conical, with a semi-circular slit near the 
apex (Fig. 4). 
On the anterior part of the dorsum of the last segment is sit- 
uated the posterior breathing organ (Figs. 2,b;5). This consists of 
two closely apposed, short, cylindrical breathing-tubes, united 
along the middle line, slightly divergent at the tip. They are 
hard, black, firmly chitinised structures, each with three slit-like 
spiracles raised on radiating carinae. Anteriorly near the middle 
line each is marked by a smooth circular plate; and the surface of 
the appendages between the spiracles bears several sharp irregular 
ridges. The alimentary canal opens ventrally on the last segment. 
The integument of these larvae is exceedingly tough but trans- 
parent. The entire dorsal and lateral surfaces are beset with 
numerous, minute, short black bristles. The ventrum is bare. 
Along the mid-dorsal line for the greater part of its length the 
dorsal blood-vessel is visible through the body -wall. It is a 
poorly-defined, dark line with five or six lateral expansions. 
This fly is only tolerably common about Columbus. I was 
able to find the young fairly common in the autumn of 1909; but 
they were rare in 1910, owing perhaps to the greater scarcity of 
their food the latter season. From the observations made it is 
probable that the larvae of the autumn generation of this fly do 
not appear before the last week in September or the first of Octo- 
