fy Pea 
VOL. XXV APRIL, 1918 No. 2 
KEY AND DESCRIPTIONS FOR THE SEPARATION AND 
DETERMINATION OF THE FIRST INSTAR STEM 
MOTHERS OF THE THREE SPECIES OF APHIDS 
MOST COMMONLY ATTACKING THE CULTIVATED 
APPLE. 
By M. T. Smutyan, 
U. S. Bureau of Entomology, Melrose Highlands, Mass. 
The following key and detailed descriptions were prepared in the 
spring of 1916, in Blacksburg, Va., while the writer was connected 
with the Virginia State Crop Pest Commission, and were to form 
part of a more extended paper, but as the publication of the latter 
has been delayed, these are submitted separately in the hope that 
they will prove of aid to those not yet familiar with the young stem 
mothers of the above three species of aphids. 
Key 
Cornicles long (about i to i of length of insect). Fig. 1, B. 
(Base of distal segment of antennz distinctly shorter than the 
flagellum or unguis or distinctly less than one-half the total 
lenethw oi ste tseement:). Pigs 1, Ay 522. . hka 1. Aphis 
malifolie Fitch (Aphis sorbt Kalt. of recent American authors). 
Cornicles short or very short (longest about of the length of an ab- 
dominal segment). Figs. 2 and 3, B. 
Base of distal segment of antenne as long or nearly as long as the 
unguis or equal or nearly equal to one-half the total length of 
the segment; cornicles about as long as an abdominal seg- 
LG ben Pe etn? Nee ATG slept G4. ya 2. Aphis pomi DeG. 
Base of distal segment of antennz distinctly shorter than the 
unguis or less than one-half the total length of the segment; 
cornicles tuberculiform. Fig. 3, A and B.....3. Aphis pruni- 
folie Fitch (Aphis avene Fab. of recent American authors). 
1The characters utilized here, as well as most of those embodied in the descriptions, can 
be made out by means of an hand lens or binocular microscope. The figures were drawn 
from balsam mounts. 
