THE ELM APHIS. 279 
Wingless specimen. — Front of the head rather obtusely advanced in the middle # 
Honey tubes very short ; length less than the diameter ; tip of the abdomen extend- 
ing or drawn out to a point, but no true tail was observed. Along the lateral mar- 
gins of the abdomen, in front of and behind, the honey tubes are minute tubercles, 
each giving rise to a hair ; these tubercles are quite distinct and about one to each 
segment. (Thomas.) On the elm in June in Wisconsin. (Bundy). 
55. Schizoneura americatia Riley. 
Curling and gnarling the leaves of the White Elm ( Ulmus americana), forming 
thereby a sort of pseudo-gall. The curl made by a single stem-mother in the spring 
takes the pretty constant form of a rather wrinkled roll of one side of the young 
leaf; but, according as there is more than one stem-mother, or as several contiguous 
leaves are affected, the deformation assumes various distorted shapes, sometimes in- 
volving quite large masses of the leaves. 
Professor Riley has given the full life history of this species in his 
Notes on the Aphididse of the United States, published in Bull. U. 
S. Geol. and Geog. Survey, from which the following is extracted: 
This species is very closely allied to the European S. ulmi (Linn.), and until I was 
^ble to compare it with actual specimens, I was in doubt whether to look upon it as a 
mere variety or a distinct species. Judging from Kessler's figure and description of 
the European leaf-curl, and by a figure sent me by Mr. Buckton, it differs from ours, 
1st, in bending upward, i. e., the stem-mother settles on the upper instead of the 
under side of the leaf; 2d, in having a number of small, rounded or verrucose swell- 
ings. These differences in their dwellings are strongly presumptive of structural 
differences in the insects themselves ; and the fact that S. americana does not attack 
the European Elms, either in Shaw's Botanical Gardens at Saint Louis, or in the 
•grounds of the Department of Agriculture, points in the same direction. Differences 
.are indeed easily enough made out if we take the more or less imperfect descriptions 
and figures of ulmi,* but are less apparent when the actual specimens are compared. 
The following are the more important differences, least subject to variation, be- 
tween the winged females of ulmi as compared with those of americana : ulmi is a 
longer-winged species, averaging 7. 3 mm in expanse; the abdomen, wing-veins, and 
stigma are darker; the terminal distance between 1st and 2d discoidals slightly 
greater ; the 3d joint of antennae is relatively longer ; the annulations are less deep 
and more numerous (those on 3d joint averaging 30) ; joints 5 and 6 are smoother, 
i. e., without annulations, but they are more setous ; joint 5 is shorter than 4 ; the 
apical, narrowed part of 6th joint is relatively longer and more pointed ; the sub- 
costal vein of hind wings is less straight ; the cubital vein is often continuous to very 
near the subcostal, while I have not found any tendency of the kind in americana, 
the tendency being in the opposite direction, or to become shorter; the 2d discoidal 
of hind wings shows a tendency to fork; the hooklets on costa of hind wings are 
3 in number, while in americana there are normally 4 ; * the legs are more setous. 
Among the more prominent of the natural enemies of this species, I have noticed, 
of Coleoptera, Coccinella 9-notata, Coccinella sanguinea (munda) Say, Hippodamia 
convergens, and several species of Scymnus. I also found feeding upon them the per- 
fect beetle of Podabrus modestus, and the Hemipterous Cyllocoris scutellatus, Uhler, 
and Capsus linearis, Beauv. ALepidopterous inquiline, namely, the larva of Semasia 
prunivora, Walsh, is also quite common within the curled leaves, feeding both on the 
lice and on the substance of the leaf. A large green Syrphus larva and several 
Chrysopa larvae also prey upon them. 
* Koch's figure (evidently copied by Kessler) is^faulty in several respects, and fails 
to indicate the hook-angle of hind wings, or the corresponding thickening of front 
wings, a fault that is, however, common to most of Koch's figures. 
