Nov. 13, 1916 
Rosy Apple Aphis 
335 
SUMMER FORMS 
The usual summer form of this species is wingless. In fact, among over 
1,000 individuals reared to maturity during the summer only 6 specimens 
of the winged form were observed. One of these died when a pupa. This 
latter insect belonged to the sixth generation from the spring migrant. 
The other 5 insects were apparently members of the third generation on 
plantain, although this was ascertained with certainty for only one indi¬ 
vidual, the other form occurring in experiments which had been set aside 
merely to maintain a surplus stock of material. Only 2 of these winged 
insects reproduced, their progeny being normal summer wingless aphids. 
Thus, while the winged insects may occur on plantain they are of no par¬ 
ticular importance in the life history of the species. 
It should be noted in connection with this form that many wingless 
insects were reared on the plants in the generations with these winged 
aphids and in the generations preceding and following them, the ratio 
being over 100 to 1. The production of this form can hardly have been 
due, therefore, to food conditions. • 
A maximum of 14 generations of the summer form were reared on 
plantain, with a possible theoretical minimum of 4 generations. 
SUMMER WINGLESS VIVIPAROUS FEMALE 
DESCRIPTION 
First instar. —Morphological characters. Antennae with the following measure¬ 
ments: Segment III, 0.176 to 0.224 mm., average 0.196 mm.; IV, (0.048 plus 0.208 
mm.) to (0.064 plus 0.248 mm.), average (0.056 plus 0.238 mm.). Cornicles 0.08 to 
0.096 mm., average 0.084 mm. 
Color characters: Pale greenish yellow with ultimately a rusty color across the 
abdomen between the cornicles. The color sometimes extends into the cornicles. 
Second instar. —Morphological characters. Antennae with the following measure¬ 
ments: Segment III, 0.16 to 0.24 mm., average 0.209 mm.; IV, 0.102 to 0.128 mm., 
average 0.107 mm.; V, (0.064plus 0-24 mm.) to (0.072 plus 0.32 mm.), average (0.065 
plus 0.288 mm.). Cornicles 0.112 to 0.144 mm., average 0.136 mm. 
Color characters: Similar to the specimens of the first instar. 
Third instar. —Morphological characters. Antennae with the following measure¬ 
ments: Segment III, 0.128 to 0.176 mm., average 0.164 mm.; IV, 0.128 to 0.184 mm., 
average 0.156 mm.; V, 0.128 to 0.144 mm., average 0.136 mm.; VI, (0.064 plus 0.288 
mm.) to (0.088 plus 0.392 mm.), average (0.076 plus 0.342 mm.). Cornicles 0.0176 to 
0.208 mm., average 0.19 mm. 
Color characters: Similar to those of the second instar. 
Fourth instar. —Morphological characters. Antennae with the following meas¬ 
urements: Segment III, 0.24 to 0.288 mm., average 0.264 mm.; IV, 0.176 to 0.24 mm., 
average 0.201 mm.; V, 0.144 to 0.192 mm., average 0.166 mm.; VI, (0.08 plus 0.36 
mm.) to (0.096 plus 0.424 mm.), average (0.086 plus 0.39 mm.). Cornicles 0.24 to 
0.272 mm., average 0.265 mm. 
Color characters: The same as those of the adult form. 
Fifth instar (adult) (PI. 22, A).—Morphological characters. Antennae slender, 
extending beyond the tips of the cornicles; measurements as follows: Segment III, 
0.416 to 0.512 mm., average 0.454 mm.; IV, 0.256 to 0.368 mm., average 0.305 mm.; 
