The Ohio £A Naturalist, 
PUBLISHED BY 
The Biological Club of the Ohio State University. 
Volume XII. MARCH, 1912. No. 5. lJRRA 
■fcVV YC ■ 
TABLE OF CONTENTS 
Metcalf— L ife-Histories of Syrphidae III 477 
Schaffner— A Revised Taxonomy of the Grasses 490 
IIine— Ohio Moles and Shrews 494 
LIFE-HISTORIES OF SYRPHIDAE III. 
C. L. Metcalf. 
Syrphus Americanus Wiedemann. 
This is one of the most common species in the state, the adults 
especially abundant about all kinds of blossoms in July and August, 
as well as very early in the spring. The larvae are active and 
greedy and found preying on a number of different aphids in large 
numbers. It would seem to be one of the most important species 
of Syrphidae in the state from an economic standpoint 
Egg. 
Elongated-ovate in outline, sub-cylindrical, narrower and 
truncate at micropylar end, nicely rounded off at the opposite 
end, broadest in front of the middle (Fig. 42); somewhat flat- 
tened to the surface to which it is attached, slightly humped or 
rounded up above (Fig. 41). Length about 0.9 mm., diameter at 
middle about 0.3 mm. Color chalk white, hence conspicuous on 
the darker surface of leaf or twig on which it is usually deposited. 
The entire exposed surface of the egg is beautifully sculptured 
except a small region around the dark micropvle. This sculptur- 
ing consists of microscopic projections of the surface arranged in 
lines running longitudinally-obliquely around the egg. Each 
projection consists of a long, slender, irregular body (seven or 
eight times as long as broad) sometimes bent, with about twelve 
to twenty slender arms reaching out in all directions from it. The 
space between these bodies is roughly a half wider than the body 
itself. Into these spaces the arms project, most of them meeting 
similar projections from the same or another body, many branching 
so as to form a delicate network of slender white anus between the 
larger bodies. Fig. 43 is a fair representation of a small part of 
the surface of the egg-shell, highly magnified. The projections 
are chalk white, the depressions between them shaded, appearing 
477 
