684 Rosert MATHESON 
The distinguishing characters mentioned in the table are well shown 
on Plate XVIII and in figure 111. In the field these can be seen readily 
with the aid of a hand lens. 
Fig. 111. ANTENNAE AND CORNICLES OF FIRST INSTAR OF STEM MOTHERS 
A, Aphis pomi: B, A. sorbi; C, A. avenae. All drawn to same scale 
