Feb. 2i, 1916 
Green Apple Aphis 
971 
occurred after the third generation, an error in which he has been followed 
by many writers. He also states that only seven generations of the 
summer forms occur, another error which hais been frequently quoted. 
WINGLESS VIVIPAROUS FEMALE (PL. LXVII, FIG. 5) 
DESCRIPTION 
First instar. —Morphological characters: Antennae (PI. LXXIV, fig. 4) as follows: 
I, 0.034 mm.; II, 0.036 mm.; Ill, 0.120 to 0.144 mm.; IV, base 0.064 mm., unguis 
0.112 to 0.128 mm.; segments III and IV imbricated and armed with a few spinelike 
hairs, III with a distal sensorium, and IV with the usual sensory group at base of 
unguis. Eyes with 12 to 14 facets; cornicles short, thick and rounded distad; legs thick, 
hind tibiae 0.239 mm. long. 
Color characters: Color very variable from a light or dark green to yellowish. In 
some cases the insects are a golden yellow; the normal color is a medium green, never, 
however, as dark as the stem mother. Appendages dusky. 
Second instar. —Morphological characters: Antennae (PI. LXXIV, fig. 3) more 
slender than those of the other instars.; lengths as follows: I, 0.045 mm. ; H» 0.046 mm.; 
III, 0.112 to 0.152 mm.; IV, 0.08 to 0.096 mm.; V, base 0.056 to 0.08 mm., unguis 
0.144 to 0.176 mm.; segments III to V imbricated and with a few spines, IV with 
distal sensorium similar to that on III of first instar, and VI with the usual group. 
Eyes with 28 to 30 facets. Cornicles rounded at the distal extremity, thick and 
imbricated. Legs stout and covered with spinelike hairs, hind tibiae 0.320 to 0.384 
mm. in length. Cauda and anal plate setose, cauda somewhat conical. 
Color characters: Similar to those of first instar. 
Third instar. —Morphological characters: Antennae (PI. LXXIV, fig. 2) rather 
long and slender; lengths as follows: I, 0.048 mm.; II, 0.051 mm.; Ill, 0.192 to 0.248 
mm.; IV, 0.112 to 0.144 mm.; V, base 0.08 to 0.096 mm., unguis 0.2 to 0.232 mm.; 
segments III to V imbricated and bearing a few spines, the base of V strongly but 
regularly imbricated but the unguis quite regularly, so giving the appearance of 
almost complete rings; sensoria as in previous instar. Eyes with 38 to 40 facets. 
Cornicles slightly rounded at distal extremity, but not nearly as much as in previous 
instars, length about 0.188 mm. Legs more slender than in previous instars, hind 
tibiae 0.448 to 0.054 mm. long. Cauda and anal plate setose, cauda bluntly conical. 
Color characters: Similar to those of first instar. 
Fourth instar. —Morphological characters: Antennae (PI. LXXIV, fig. 10) long 
and slender; lengths as follows: I, 0.62 mm.; II, 0.06 mm.; Ill, 0.144 to 0.192 mm.; 
IV, 0.134 to 0.176 mm.; IV, 0.152 to 0.192 mm.; VI, base 0.088 to 0.112 mm., unguis 
0.248 to 0.304 mm.; segments III to VI distinctly imbricated and armed with a few 
prominent hairs, segment V with a distal sensorium (the original III of first instar now 
represents III, IV, and V). Eyes with about 58 facets. Cornicles rather slender, com¬ 
pared with the earlier ones, cylindric, imbricated, and about 0.264 mm. long. Hind 
tibiae 0.672 mm. long. Cauda and anal plate setose, anal plate rounded, cauda bluntly 
conical. 
Color characters: Similar to those of first instar. The appendages are here partly 
turned to the black color met in the adult form. The cornicles blacken from the 
distal extremity proximad. 
Fifth instar (adult). —Morphological characters: Antennae (PI. LXXIV, fig. 1) 
long and slender compared with the early instars, but short compared with the body; 
lengths as follows: I, 0.064 mm.; II, 0.063 mm.; Ill, 0.224 to 0.320 mm.; IV, 0.176 to 
0.240 mm.; V, 0.176 to 0.232 mm.; VI, base 0.104 to 0.128 mm., unguis 0.28 to 0.32 
mm.; segments III to VI imbricated and with a few stout hairs; sensoria as in fourth 
instar. Vertex slightly rounded. Prothorax with a prominent tubercle on each side. 
22534°—-16-2 
