22 BULLETIN 526. U. S, DEPARTMENT OE AGRICULTURE. 
The wing veins are not reduced in most species. In some, however, 
the radial sector of the fore wings is very faint or entirely absent. 
This condition is met with in several genera of the Callipterina. That 
it is this vein which is lacking is indicated by the trachea of the freshly 
emerged wing. Here the media is represented by M..M 2 . and 1 
The cubitus and first anal are distinct trachea?, whereas the second 
anal is faintly indicated. In the hindwing besides the radial sector 
three oblique tracheae are present: these are the media, cubitus, and 
first anal. Only the media and cubitus are represented in the vena- 
tion, 
Considerable variation is met with in the cornicles of this tribe 
but they are never long and prominent as in the Aphidini. The usuai 
form is the truncate one represented in Myzocallis. Chaitophorus. etc. 
Yery often the cornicles are sculptured. In some cases thev 
are reduced ro small cup-shaped structures and in others they are 
represented by mere rings. 
The antennae, as a rule,, are long and slender and armed w 
- nsoria. These sensoria are usually small, subcircular or oval. In 
rare oases they are somewhat elongate. 
The cauda in this tribe is as a rule knobbed and the anal plate 
bilobed. In some cases, however, the cauda and anal plate are both 
rounded. In the Saltusaphidinu aal plate is divided and the 
cauda remains distinctly knobbed. 
Wax secretion is present to a limited extent in this tribe. It is 
most developed in the Phyllapliidina. Here there are large lateral ab- 
dominal wax plates in all of the forms and the insects present a wool- 
like appearance on the foliage. In the genus Euceraphis wax secretion 
is found to a limited extent. In one species, mucidus Fitch, it is, 
however, abunda - the insects of this species often seem to 
float in the air. a peculiar appearance common also in the Erieso- 
matinae. In the Saltusaphidina also distinct wax plates occur, 
particularly in the oviparous forms. These are arranged along the 
abdominal segments. 
Tiie habit of leaping is common in the Saltusaphidina as the name 
implies. Here the muscles of the femora are greatly enlarged for this 
purpose. Many of the other members of the tribe approach this con- 
dition, especially in the genus Monellia. Others, although they do not 
distinctly leap, drop so suddenly when disturbed that they almost ap- 
pear to leap from the foliage. Our common Symydobius on the 
birch is difficult to collect on account of such a habit and other forms 
of Callipterina are very similar in action. Certain species in this 
tribe are closely attended by ants in return for the honeydew excreted. 
Some species are protected by these Hymenoptera by means of sheds 
or roofs built over colonies on the leaves or twigs. These sheds are 
found quite commonly upon the leaves of the oaks protecting the spe- 
