A STUDY IN WING VEINATION. 
Family Aphididae. 
BY C. E. BARTHOLOMEW. 
The purpose of this paper is to give the results of a study of the wing 
venation in the family Aphididae with a view of replacing the arbitrary nomen- 
clature as applied to this family by the general nomenclature of wing venation. 
If the venation of the wing as found in the more generalized Aphid (fig. 21 
of the subfamily Aphidinae is compared with the arrangement of the veins of a 
hypothetical wing (fig. 1). it will be seen that there is little or no resemblance. 
If, however, the wing of the developing nymph (fig. 3) is studied the resemblance 
is so close that but slight chance for mistake exists and the key to the venation 
of the adult wing is found. 
In the wing of the young nymph the venation is nearly the same as in the 
hypothetical wing. In this case the subcostal vein (Sc) is two branched. The 
radical vein (R) is four branched, branch one (Ri) is not very well developed 
and branches four (lU) and five (Rs) have coalesced. The medial vein (M) 
is three branched instead of four, but this loss is common when there is a re- 
duction of this area of the wing, for instance, as in the Diptera. The cubital 
vein (Cu) is normally two branched, as it is in the hypothetical wing. There 
is but one anal vein (A). 
In studying the wing of the mature nymph (fig. 4) the venation will be 
seen to be the same as in the mature wing except that the coalescence of the 
bases of the veins has not taken place. 
This points out the veins which have been lost thru coalescence and the 
manner in which the reduction has taken place. The subcostal and radial areas 
are greatly reduced, as is also the anal area. The medial and cubital areas re- 
main unreduced or possibly increased except in the proximal portion of the wing 
where all the cells have been lost. The result is that where there has been a 
reduction in area there has also been a reduction in the veins by coalescence. 
This coalescence has taken place to such an extent that all the veins have been 
lost either wholly or in part. The radial and subcostal veins even in the young 
nymph show a crowding together which in the older nymph have coalesced into 
a once branched vein, the main portion of which is composed of the coalesced 
subcostal and radius, and the branch, of the coalesced branches of the radial 
sector. The medial vein in the mature nymph is the same as in the young 
nymph. The cubital vein is bifurcated nearer the base and the anal vein lies 
nearer the anal margin of the wing. 
In the adult wing of the more generalized Aphid (fig. 2) the venation ap- 
pears as a single, much-thickened longitudinal vein from which arise four branch 
(173) 
