WILLOW APHIDES. 593 
wider apart at their tips thau at their bases; third vein two-forked ; hind wings 
with a subcostal and two discoidal veins, the latter very closely approximate at 
base and divergent at tip. Thighs dark honey-yel- 
low, broadly tipped with black ; tibia? dusky, red- 
dish at the base. 
The honey-tubes are subobsolete. The dots on the 
abdomen are very distinct, especially on the fully 
grown, wingless individuals. In the intermediate 
rows the dots are six in number, the two middle 
ones being smaller than the others. Just behind the 
middle of the abdomen, and occupying the place of _ ,„ _ ... . .. 
' rJ " ' Fig. 195. — Lacknus dentatus ; en- 
tile two middle dots in the fourth row, is a somewhat larked. After Forbes, 
conspicuous black, conical protuberance, varying in 
size in different individuals, and sometimes considerably more prominent than it is 
represented in the figure. Length, two-twelfths of an inch ; expanse of the wings, 
six-tenths. 
88. Chaitophorus nigrce Oestlund. 
Found by Mr. Oestlund on the leaves of Salix nigra as late as Octo- 
ber 26. 
Winged form. — Similar to Aphis in general appearance. Entire insect with long 
white hairs. Head black, rather straight in front. Antennae about as long as the 
body, black except base of in ; I and II as usual and subequal, in longest, iv a little 
shorter, V a little shorter than iv, VI about^one-half of V, vn as long as iv, setaceous ; 
in to v moderately cicatrized. Eyes dark reddish-brown, with a prominent tubercle. 
Beak rather short, hardly reaching second coxae, pointed. Thorax all black, pro- 
thorax well developed, pronotuni not narrowed in the middle. Wings as usual. 
Legs with the femora more or less blackish, and the tibiae pale. Abdomen wholly 
black or slightly pale, brown along the sides. Honey-tubes tuberculiform, not longer 
than broad, thickest at base, usually paler than the body, Style tubercle-like, or 
even knobbed as in Callipterus. Leugth of body .06; to tip of wings .10. 
Wingless form.— General color a dull blackish-brown. Body flat, obovate or oblong, 
quite hairy and tubercular in young specimens, becoming smooth in full-grown. 
Antennas about one-half the body or a little longer, pale at base, dusky towards the 
apex; relative length of the joints as in winged form; joints with long white hairs, 
not very numerous. Abdomen usually with the middle and the margins slightly 
paler. Honey-tubes as in the above form. Length of body .06. (Oestlund.)* - 
89. Iihopalosiphum salicis Monell. 
This aphid occurs on the under side of leaves of Salix lucida, S. nigra, 
and S. babylonica. 
Winged individuals. — Head and thorax dusky ; abdomen green, with various irregu- 
lar, darker green markings. Antenna? about half as long as the body, not mounted 
on frontal tubercle; the third and fourth joints somewhat dentate; apical joint half 
as long again as the preceding ; third and fourth joints often subconnate. Nectaries 
light green, reaching to the tip ; the basal portion slender, expanding at the middle 
to twice its former diameter, and again suddenly contracted at the mouth, which is 
furnished with the usual annulus. Tail yellowish, about one-third as long as the 
nectaries. Length 1.52 mm ; to tip of wings, 3.04 ram . Apterous individuals entirely 
pale green, with two darker dorsal vitta?. 
90. Chianaspis salicis (Linn.). 
Specimens of Ghionaspis fraxini received from England, states Pro- 
fessor Oomstock {Ag. Rt., 1880), are identical with G. salicis received 
* Fourteenth Ann. Rep. Geol. and Nat. Hist. Survey Minnesota, 1886, p. 49. 
5 ENT 38 
