100 BRITISH APHIDES. 



ratlier smoky in tint. The cubitus and other veins 

 black ; stigma broad and dilated posteriorly. Legs 

 moderately long and black. The wings are generally 

 carried pentwise, but sometimes the horizontal position 

 is assumed. 



Some years this insect is very plentiful throughout 

 June and July on the common Elm, TJhnus camjpestris. 

 On shaking the boughs, abundance of the flocculent 

 matter falls, mixed with numerous colourless globules. 

 These have been previously voided from the anus of the 

 insect, and being dusted with mealy matter, do not soil 

 the surfaces on which they roll. They have the appear- 

 ance of grains of bright silver sand, and freely run on 

 glass without wetting it. If breathed upon, however, 

 they burst and leave only a spot of liquid, together with 

 fragments of what would appear to be a film or delicate 

 membrane. These globules are not alone produced 

 by Sckizoneurci, but they seem to be a usual accompani- 

 ment to those Aphides which nest in close covered 

 structures. 



It is suggested that by the isolation of these globules 

 the insects are not contaminated by their own excreta. 



Prof. Riley describes an elm Aphis under the name 

 of Schizoneura Americana, and which be thinks is 

 distinct from Scli. ulmi of Europe.* One peculiarity 

 of this insect is, that it rolls the leaves from below 

 upwards, from which I gather that it feeds on the 

 upper surfaces instead of on the lower, as with us. 

 There appears also to be some slight variation in the 

 wing-veining, and in the occurrence of four instead of 

 three booklets on the lower wings. f 



In ' Notes on the Aphididse of the United States,' 

 Messrs. Riley and Monell have given a full and interest- 

 ing account of this insect, and they may be congratu- 

 lated on their success in tracing the steps of develop- 

 ment throughout the six generations which intervene 



* ' Bulletin of Survey,' vol. v, No. 1, 1879. 

 . t Those Britisli insects wliicli I Lave examined sliow also four liook- 

 lets on the loAver wings. — G. B. B. 



