84 
The Ohio Naturalist. 
[Vol. XIII, No. 5, 
Eristalis aeneas Scopoli. 
(Plate V, Figs. 131 to 141 and 145 to 14S; and Plate IV, 
Figs. 149, 150.) 
Egg. 
The egg of Eristalis aeneas was not found but that of its near 
relative E. tenax was studied and is figured in Plate V, 
Fig. 142. 
These eggs are much larger than those of most of the aphid- 
iphagous species studied, but are equaled in size by the egg of 
Didea fasciata. Length 1.6 mm., diameter 0.4 mm., elongate 
ovoid, slightly bent, rounded at the ends, the anti-micropylar end 
the larger. The shell shows the usual sculpturing but the radi¬ 
ating arms between the main bodies arc much less conspicuous or 
at times apparently wanting (Fig. 143). There are about 65 
bodies the length of the egg, about 100 around it at the middle. 
Each body is about two or three times as long as broad, with 9-13 
short arms radiating from it. The bodies are well separated from 
each other. The color is the usual chalk-white. 
A female of E. tenax was taken at the city sewage disposal 
plant while ovipositing over filth, September 23. Within an 
hour and a half after being taken she had deposited about 100 
eggs. Part of these were deposited in more or less scattered 
positions; the great majority, however, in one or two masses, in 
which they were ranked on end, their sides closely apposed. They 
were floated over a vial of water, and within 24 hours a consid¬ 
erable number of them had hatched and were to be seen crawling on 
the vial or wriggling in the water. 
Larva. 
The young larva of E. tenax (Fig. 144) is scarcely longer than 
the egg except for the projection of the posterior respiratory 
appendage. Including this structure the length, 2 or 3 hours after 
hatching, was 2.5 to 3 mm. The larvae are sub-cylindrical 
but attenuated at the posterior end to the breathing tube (Fig. 
144, d ). They frequently show a prominent hump dorsally in the 
posterior third of the body. Antennae (a), prolegs ( b ), tracheal 
trunks ( c ), and other larval structures are present but these are 
described below for the larva of E. aeneas. 
The mature larva of Eristalis ecneas (Fig. 131) resembles in a 
general way the well-known rat-tailed larva of E. tenax , but is 
considerably smaller. 
The body is soft, slug-like, elongate-oval or sub-cylindrical in 
shape, about 13 to 15 mm. long by 3 to 4 mm. broad and 2 to 3 
mm. high; these dimensions varying with the different positions 
assumed by the motile larva. The anterior end is commonly 
