102 
Psyche 
[September 
C. pruni Osborn and Drake 
The average length of valve one is 0.42 mm. with 
variation between 0.40-0.45 mm. Valve two varies from 
0.34-0.41 mm. and its average length is 0.38 mm. Valve 
two is triangular with a convex base. The subgenital plate 
is circular. 
C. ulmi Osborn and Drake 
Valve one varies in length from 0.47-0.44 mm. and 
its average length is 0.46 mm. Valve two varies in length 
from 0.32-0.41 mm. and its average length is 0.37 mm. 
The shape of valve two is elongate and tapers at its distal 
end. The subgenital plate is elliptical. 
III. Characters of taxonomic value 
The features of taxonomic value in separating the 
New England species of Corythucha are: the shape of the 
ventral aspect of a pair of second valves, the length of 
valve two, the shape of the lateral aspect of valve one, the 
length of valve one, and the shape of the subgenital plate. 
On the basis of the above characters, ten species 
can be easily separated. The remaining three species which 
could not be separated in this way are: C. juglandis, C. 
heidemanni, and C. coryli. 
1 VI 
2 VI 
C. arcuata 
0.31 mm. 
(10) 
0.26 mm. 
(4) 
C. mollicula 
0.31 
(13) 
0.26 
(9) 
C. marmorata 
0.39 
(12) 
0.32 
(9) 
C, cydoniae 
0.40 
(13) 
0.33 
(5) 
C« pruni 
0.42 
(9) 
0.38 
(3) 
C . coryli 
0.46 
(7) 
0.43 
(6) 
C, ulmi 
0.46 
(6) 
0.43 
(6) 
C\ pergandei 
0.47 
(17) 
0.41 
(4) 
(7. juglandis 
0.49 
(7) 
0.45 
(4) 
C. caryae 
0.50 
(11) 
0.43 
(6) 
(7. heidemanni 
0.51 
(13) 
0.45 
(6) 
C. pallipes 
0.54 
(9) 
0.49 
(5) 
C. ciliata 
0,58 
(ID 
0.53 
(6) 
Table 1. Average 
comparative lengths of valves 
one and two. 
The 
numbers 
in parenthesis 
indicate the 
actual number of 
measurements determined for each case. 
