Nov. 13, 1916 
Rosy Apple Aphis 
327 
Segments IV and V quite distinctly imbricated. Eyes with about 3 5 facets; cornicles 
0.12 to 0.128 mm., average 0.123 mm., rather thick. 
Color characters: Considerably lighter than specimens of the first instar, although 
still of a somewhat greenish shade. 
Third instar. —Morphological characters. Antennal segments as follows: III, 
0.2 to 0.224 mm., average 0.213 mm.; IV, 0.096 to 0.112 mm., average 0.106 mm.; 
V, (0.072 plus 0.16 mm.) to (0.088 plus 0.208 mm.), average (0.08 plus 0.177 mm.). In 
this instar Segment III sometimes shows division, in which case Segments III and IV 
have about the following proportions: III, 0.144 mm.; IV, 0.112 mm. Eyes with a 
large number of facets; cornicles still stout and measuring 0.144 to 0.176 mm., average 
0.16 mm. 
Color characters: Approaching those of the adult insect. 
Fourth instar, —Morphological characters. Antennal segments as follows: III, 
0.192 to 0.24 mm., average 0.216 mm.; IV, 0.112 to 0.16 mm., average 0.128 mm.; 
V, 0.128 to 0.152 mm., average 0.136 mm.; VI, (0.08 plus 0.184 mm.) to (0.112 plus 
0.24 mm.), average (0.096 plus 0.213 mm.). Cornicles 0.1224 to 0.256 mm., average 
0.227 mm * 
Color characters: Almost those of the adult insect. 
Fifth instar. —Morphological characters. Antennal segments as follows: III, 
0.336 to 0.384 mm., average 0.352 mm.; IV, 0.192 to 0.224 mm., average 0.2 mm.; 
V, 0.144 to 0.176 mm., average 0.16 mm.; VI, base, 0.096 to 0.112 mm., average 0.099 
mm.; unguis o 192 to 0.224 mm., average 0.208 mm. Segments imbricated, the first 
segment being distinctly ridged on its inner margin and armed with a number of 
slightly capitate hairs. Antennae on frontal tubercles, these being armed on their 
inner edge with slightly capitate hairs; vertex slightly protruding; crown armed with 
numerous hairs and near its caudal margin with a pair of distinct tubercles (in many 
specimens only one of this pair present and in other specimens neither); eyes promi¬ 
nent, their tubercles small; pfothoracic tubercles not as prominent as in the later forms; 
abdomen with distinct lateral tubercles and fine hairs; the last two abdominal seg¬ 
ments each with a pair of distinct dorsal tubercles; cornicles subcylindric, 0.288 to 
0.32 mm., average 0.305 mm., considerably broader at the base than at the apex, 
slightly flanged and strongly imbricated; cauda conical, short, densely setose and 
covered with numerous long hairs; anal plate rounded and similarly armed; legs 
with short stiff hairs, femora rough and covered with sensory-like markings, hind 
tibiae 0.83 mm. long; form very globose, the abdomen not showing segmentation; 
length from vertex to tip of cauda 1.68 mm; width of abdomen 1.44 mm. 
Color characters: General color reddish or purplish brown, dusted with a bluish 
white powder. Antennae, with the exception of the basal portion of Segment III and 
sometimes Segment II, black; head and prothorax dark brown or blackish; abdomen 
varying shades of brown or purplish with a few minute dark markings which include 
the lateral tubercles; cauda and anal and genital plates black; cornicles black; legs 
entirely black with the exception of a light ring at the base of each femur; color 
between and surrounding the cornicles rusty. 
Location: Found within the curled leaves of the apple, usually entirely hidden by 
the tightly rolled leaf. 
LENGTH OF NYMPHAL LIFE 
When newly hatched, the stem mother wanders about on the twig until 
a bud is reached. Here she settles and commences feeding, crowding 
down into the bursting bud. Before feeding she has a wrinkled appear¬ 
ance, but begins to fill out in a day or two. 
The duration of the first instar is considerably longer than that of the 
following ones, but this depends a good deal on weather conditions. If 
