18 BRITISH APHIDES. 



with black. Nectaries pale. Tail large and obtuse. 

 Legs short. 



The Pupa. 



Less linear than the pupa of C. carpini, which Pas- 

 serini considers to be identical with C. coryli. 



Winged viviparous female. 



Incli. Millimetres. 



Expanse of wings 0'265 6'72. 



Size of body 0-065 X 0'025 1-64 X 0-62. 



Length of antennae 0*060 1*52. 



„ cornicles 0-007 0*17. 



Wholly pale yellow, or else citron yellow. Head 

 rather broad. Vertex prominent. Cornicles yellow. 

 Legs short. Wings hyaline and not clouded with 

 brown. Insertions, stigmata, and veins yellowish green. 



Sometimes this little Aphis swarms by hundreds 

 under the leaves of the hazel, Gorylus avellana; forty 

 or more being crowded on a single leaf. At other 

 times the Aphis shows a more solitary habit. Kalten- 

 bach says it affects also Carpinus hetulus and even 

 Fraxhius excelsior. Their activity appears to be much 

 less than that shown by the Gallipteriis of the birch. 



Walker says that this nut-Aphis is much preyed on 

 by the little Myina flava, which insect is also parasitic 

 on G. quercus and perhaps on Pterocallis tilice. 



The oviparous female greatly resembles the vivi- 

 parous female, but the abdominal apex has a squarish 

 termination, and the last ring is furnished with well- 

 marked geneto-anal valves. Several specimens were 

 secured in the month of November, and they contained 

 from three to five forward ova. Most of the hazel- 

 tree leaves had then fallen, and the rest were dry and 

 yellow. Probably the eggs, when mature, are deposited 

 in crevices of the bark. Nevertheless, I have failed 

 to find them in such places. 



