OALLIPTERUS. 13 



received the names of Zierlause in Germany, and Gray- 

 louse in America. 



The generic characters are sufficiently distinct ; but 

 nevertheless on account of the recurring difficulty, as 

 to what constitutes a true articulation of the antenna, 

 these insects have been variously placed, with or out- 

 side of the Lachninge. Amongst the species named by 

 Koch and Passerini, some have the antennal joint 

 more than twice the length of the preceding, whilst in 

 others it by no means equals the same. I consider, in 

 accordance with the American systematists Riley, 

 Monell,* and Thomas,! that these longer terminals 

 have as much right to be considered true articulations, 

 as those we find in Chaitophorus ; and this, coupled 

 with the extreme shortness of the rostrum, and the 

 different habits of life, I think quite justifies us in the 

 separation of CaUijoterus from the group to which 

 Lachnus belongs. 



Although the dark cloudings which border the veins 

 of the upper wings of these insects are not to be found 

 in all the species — and, indeed, are not peculiar to 

 CalUpteruSj yet they give an elegant and marked cha- 

 racter to the Aphis, which should not be disregarded 

 in the notes of their diagnosis. 



As a rule, their bodies are light in weight, and 

 prettily barred with rich brown on a yellow or greenish 

 ground colour. The wings are voluminous, and pos- 

 sess the same number of veins and furcations as in all 

 the genera previously described. 



The Calli2)teri nowhere form large companies or 

 swarms like Aphis proper, but aff"ect a more solitary 

 habit of life, only two or three being usually found 

 under one leaf. The hazel Aphis, however, will some- 

 times congregate to fifty or more under a single leaf. 

 These, probably, are the progeny of a single parent, 

 often to be found amongst them. 



* 'Notes on Aphidida3 of the United States.' Riley and Monell, 

 1879. P. 28, et seq. 



t ' Eighth Report on Noxious and Beneficial Insects of the State of 

 Illinois.' By Prof. Cyrus Thomas. P. 109. 



