A SYNOPSIS OF THE APHIDIDAE 31 



I made a very careful study of specimens from California, sent me by David- 

 son, and of specimens collected both in Indiana and New York (type locality). 

 I was unable to find any structural differences that would definitely separate the 

 two lots of specimens, with the exception of the position of the wings. These are 

 laid flat when at rest in the eastern specimens, but are not so in the Californian 

 specimens, according to Davidson. In spite of this apparent agreement, I feel 

 that the two must be distinct. 



If this is the case, that the wings are not laid flat at rest, this 

 species must belong to the genus Callipterus, and therefore cannot be 

 Monellia caryella (Fitch). However, the author has not had an 

 opportunity to study this carefully, so leaves it as it is, calling this 

 California species Monellia caryella (Fitch). 



Because of the fact that all the species of aphids on walnut are 

 so closely related, and so very similar in structure, a key to separate 

 them, one from another, is given here. This key is adapted from 

 Davidson. 8 



1. Cornicles quite evident, about as long as wide. 



Chromaphis juglandicola (Kalt.) 



Cornicles barely perceptible, considerably wider than long * 2 



2. Tibiae of alate viviparae entirely dusky Callipterus calif ornicus (Essig) 



Tibiae of alate viviparae mostly pale 3 



3. VI spur longer than VI base. Oviparous females with four longitudinal rows 



of capitate hairs Callipterus caryae Monell 



VI spur shorter than VI base. Oviparous females with six longitudinal rows 



of capitate hairs Monellia caryella (Fitch) 



11. Genus Callipterinella Van der Goot 



Van der Goot, Zur Systematic der Aphiden, 1913. Type Aphis (Callipterus) 

 betularius Kaltenbach. 



27. Callipterinella ammlata (Koch) 



Koch, Die Pflanzenlause, p. 1855. Chaitophorus (orig. desc.). 

 Gillette, Jour. Econ. Ent., vol. 3, p. 367, 1910, Chaitophorus betulae (Buck- 

 ton) (list). 

 Davidson, Jour. Econ. Ent., vol. 10, p. 292, 1917 (desc.). 



Eecords. Betula alba; Oakland, Walnut Creek (Davidson). 



This species has been reported by Davidson as infesting the leaves 

 and shoots of the white birch in the San Francisco Bay region. It is 

 unknown to the author. 

 s Ibid., p. 35. 



