Feb. 21,1916 
Green Apple Aphis 
969 
0.296 to 0.416 mm.; IV, 0.16 to 0.192 mm.; V, base 0.096 to 0.12 mm., unguis 0.16 to 
0.184 mm.; segments III to V imbricated and armed with several prominent spinelike 
hairs, segment IV with a distal sensorium, and V with the usual group. Eyes promi¬ 
nent and with very many facets, ocular tubercles distinct; lateral thoracic tubercles 
prominent; abdominal tubercles not so prominent. Cornicles cylindric, tapering, 
imbricated and sometimes slightly flanged, 0.288 to 0.368 mm. in length. Cauda 
narrow, conical, or very slightly constricted toward its middle, densely setose and 
armed with a few long curved hairs. Anal plate rounded, setose, and hairy. Legs 
slender, hind tibiae 0.752 to 0.88 mm. long. Body quite globose, more so than that of 
summer form. Length, 1.92 mm.; width, 1.25 mm. 
Color characters: General color green, somewhat darker than the summer forms; 
vertex and crown black; cornicles, cauda, and anal plates black, as are also the tarsi 
and the distal extremities of the tibiae, femora, and labium; eyes deep brown. The 
entire insect is sometimes covered with a bloom. 
LENGTH OF NYMPHAL LIFE 
The newly hatched stem mothers spend the first day wandering about 
over the twig on which they were born, doing little or no feeding. They 
finally settle on the tiny leaves or. in some instances on bndi in which 
the green of the leaves barely shows. From this time on they feed 
almost continuously, seldom changing their positions unless the food is 
very poor. In that case they may wander about on the twigs. Such 
insects, however, are very likely not to settle permanently nor to live 
to reproduce. 
The duration of the first instar of stem mothers averages from 4 to 5 
days; that of the next three, 6 days, the time being equally divided 
among the three. The total nymphal life thus averages from 10 to 11 
days. That the first instar is longer than the three others, and also 
longer than the first instar of later generations, is due to the fact that 
the young stem mother loses one or more days in searching for suitable 
food. Prolonged cold spells would undoubtedly retard this development 
somewhat, but the insects can withstand short spells of severe weather 
with little or no apparent effect. Poor food conditions would probably 
check their growth also, but this factor is negligible, since the same con¬ 
ditions which induce hatching also cause the buds to burst, so that the 
food is practically always ready for the insects. Moreover, as stated 
previously, insects which fail to locate good food, and wander about, 
seldom reach maturity. 
REPRODUCTION 
The stem mothers begin to reproduce in about 24 hours after becoming 
adult. In the experiments of the writers the greatest number of young 
produced by one stem mother was 42, during a period of 10 days. In 
most of the species which have been carefully studied the average repro¬ 
duction by stem mothers is greater than that by any of the succeeding 
generations. Considerable difficulty was experienced in handling this 
