122 BRITISH APHIDES. 



Variety a. 



Bright green. Head and thorax shining black. 

 Abdomen green, with eight or nine transverse black 

 bars, accompanied by four marginal spots on each side. 

 Antennas yellowish green, very hairy, as also are the 

 leofs. Cornicles small and black. 



Variety (3. 



During the spring and summer months, that is, 

 from the middle of May to early August, winged 

 females of this species, which are larger than the above, 

 may be found on the leaves of the sycamore-tree. 

 Their colours are uniformly of a shining black, with 

 the exception of their wing-insertions and tibias, 

 which are orange or yellow coloured. The whole 

 insect is pilose, and the wings are longer than those 

 seen in variety a. But the principal interest of this 

 insect consists in the different character of the young 

 it produces, which are quite removed from the ordi- 

 nary type of Aphis. In all the cases I have examined, 

 the young included in the abdominal cavity are ab- 

 normal, and after birth present so peculiar a form that 

 they require a special description. This will appear 

 under the heading of Dimorphism of C. aceris. 



Pupa. 



This is smaller and paler in colour, but it does not 

 greatly differ in form the apterous female. The wing- 

 cases are greenish. 



The males. 



This sex appears under two forms viz. apterous and 

 alate. It is well known that the male of Aphis, like 



