SYNOPTICAL KEY TO THE APHIDIDAE OF MINNESOTA 119 
their smaller size and elongated body; they are found on the needles 
of pines and not on the bark, and usually with some green or paler 
colors. They are of much interest as showing the probable line of 
modifications leading to the two higher series of tribes of the sub- 
family. Several genera are already recognized in the tribe, of which 
we have one and probably a second: 
a. Antennae 6-jointed; media of fore wings simple, not branched.......... 
Genus UNILACHNUS 11 
b. Antennae 5-jointed; media with one branch......... Genus ESSIGELLA 12 
11. Genus UNILACHNUS Wilson, 1919. Type: Lachnus parvus 
Wilson, 1915. Size small; antennae 6-jointed; media simple; found 
on needles of pines. Only one species is known: 
(8) UNILACHNUS PARVUS (Wilson) Wilson, 1919 
This species, the smallest known of the Lachnina, has been taken 
on the needles of White pine in Minnesota. 
12. Genus ESSIGELLA Del Guercio, 1909. Type: Lachnus cali- 
fornicus Essig, 1909. Antennae 5-jointed; media of fore wings with 
one branch. Found on needles of pines; colors green or yellowish- 
green. A genus with only one species known. This may be found 
in Minnesota as it 1s reported from both east and west of us. 
(—) ESSIGELLA CALIFORNICUS (Essig) Del Guercio, 1909 
13. Group TRAMINA. The group is readily separated. from the 
Lachnina by the radial sector arising, not from the distal end of the 
stigma, but from the middle or some distance back of the tip of the 
stigma and running as a more or less curved vein to the margin of the 
wing. None are found on conifers but on woody parts of deciduous 
trees and other woody plants; some are to be found on roots and 
underground in-nests of ants. While the group contains some of the 
largest forms known in the family, it also has several medium or 
smaller sized forms. Two tribes are recognized: 
a. Feeding on woody parts of trees; tarsal joints as usual in the family.... 
Tribe PTEROCHLORINI 14 
b. Feeding underground on roots, or found in nests of ants; tarsi of hind 
legs very long, nearly as long as the tibia.......... Tribe TRAMINI 18 
Me ibe- LE ROCHLORINIG (Size usually. large +.stigma: of 
fore wings long and narrow, sometimes short and broad as usual 
in the family; radial sector arising from the middle of the stigma, 
or at least some distance back of the apex, and running as a more or 
less curved vein to the margin of the wing. While the stigma may 
be truncate as in the Lachnini, it is more often rounded and ends 
