56 SEVENTEENTH Reporr STATE EntTomoLocist oF M1INnNEsSoTA—1918 
part under the Pemphiginae. Thomas (1879) has the genera dis- 
tributed under Aphidini, Lachnini, and Pemphiginnae. O¢cstlund 
(1887) united Chaitophorus and related genera with Callipterus and 
related genera under the tribal name Callipterini, based mainly on 
similar type of cornicles and cauda. |Mordwilko distributes the 
genera under the subfamilies Aphidinae and Pemphiginae. Wilson 
(1910) first united the genera under the three tribes Pterocommini, 
Chaitophorini, and Vacunini in the Callipterinae. The three tribes of 
Wilson are considered under the group Chaitophorina. 
Morphological characters. Head transverse; frontal margin 
straight or but slightly concave. Antennae usually shorter than the 
body and not on frontal tubercles, or on very indistinct ones; spur of 
terminal segment elongated and distinct, usually longer than the prox- 
imal part; sensilla long and slender as in the Lachnina, but not as 
numerous; marginal sensoria sometimes scattered but more often 
grouped close together near the margin of the primary sensorium. 
Rostrum very short in the leaf inhabiting forms, longer in the bark 
ieeders. Wings with typical venation, or reduced in the Vacunini; 
veins often found in dusky bands. Cornicles of the truncate type; 
usually not longer than broad, or if longer more or less enlarged in the 
middle. Cauda short and broad as in Lachnina, or elongated and 
pointed; in some the apex is distinctly globate as in the Callipterina. 
Anal plate with distal margin entire, rarely slightly emarginated. Body 
usually elongate and somewhat depressed, provided with long hairs. Dis- 
tinctive characters of the tribe that separate them from the Lachnina 
are the short rostrum, the grouping of the marginal sensoria, and the 
cornicles and cauda. 
Biological characters. Not a few of the present group are found 
as bark feeders on the trunk and limbs of deciduous trees; these are 
usually of a large size, approaching in this respect the Lachnina. The 
larger number of the group are found on tender twigs and on the leaves 
of trees, rarely on annual plants. The Vacunini are anomalous forms, 
which most writers have placed with the Pemphiginae on account of 
their one branched media and reduced cornicles, but a more critical 
examination of the tribe shows that they are better associated with the 
Chaitophorina. Following Hartig, too great weight has been given to 
venation by authors, and many unnatural relations have been estab- 
lished as a result. Venation is a character of primary importance in 
the family, but when taken unsupported by other characters has no 
more value than those of the antennae, cornicles, cauda, ete. 
