Feb. si, 1916 
Green Apple Aphis 
979 
nearly the color of the abdomen, while in some others they are a dusky gray. In 
specimens that have wings as large as the normal hind wing of the winged form, these 
wings are transparent like those of the winged. In other color characters this form 
resembles the wingless female. 
COMPARISON WITH USUAL FORMS 
Up to and through the pupal stage these insects appear to be identical 
with the immature stages of the true winged aphides. In fact, the writers 
are not able to distinguish the pupal molts from which intermediates 
emerged from those shed by the winged insects. 
The adults, however, more closely resemble the wingless individuals 
than the winged, in general bodily outline. They lose the “corseletta” 
of the thorax, which latter at the same time becomes less distinctly 
differentiated from the abdomen, conforming quite closely to the wingless 
form. The darker color is also lost, the head and thorax being con- 
colorous with the abdomen. 
Two indications of the winged character are retained, however. These 
insects bear rudiments of wings, varying from wings of nearly half size, 
with indications of some of the veins, to tiny pads which are hardly more 
than wrinkles of the skin. Also the antennae of this form bear, on the 
third segment, sensoria like those of the winged insects, which are absent 
in the wingless form. These, however, g,re not normal, in that usually 
the entire six are not present, the numbers on the two antennae vary, 
and the sensoria are not of uniform size, very few being as large as the 
normal ones. 
One other interesting point is that the dorsoventral muscles of the 
thorax, which are developed in connection with flight, are very much 
reduced in all specimens and the longitudinal thoracic muscles are 
reduced in varying degrees, the amount of reduction in both cases 
coordinating quite closely with the reduction exhibited by the wings. 
The writers (19) believe these intermediates to be variants between the 
winged and wingless forms, and of perfectly normal occurrence, illus¬ 
trating the steps by which the wingless condition has been attained in 
the Aphididae. 
OCCURRENCE 
Intermediates were of rather common occurrence, being observed, as 
stated above, in 16 experiments. In all, 31 individuals were found. 
LENGTH OF NYMPHAL LIFE 
The nymphal period was of the same length as that of the winged form. 
In fact it was impossible to distinguish between the two forms in any 
manner, until the adult condition was attained. 
