Puant Lice Insurtnc FouiacE AND FRUIT OF THE APPLE 7Al1 
of a species that normally migrates to a summer host plant gradually 
acquiring the ability to reproduce continuously on its primary host. 
The production of a maximum of eight broods on apple at Vienna, Georgia, 
and the rearing experiments of Brittain (1915b), would lend support 
to Ross’s experimental work. 
Another point of considerable importance is whether, during the summer, 
winged or wingless forms on plantain can migrate to apple and produce 
generations thereon. Brittain (1915 b) succeeded in one case in making 
such a transfer, using the progeny of the fourth generation on plantain. 
These matured and produced young which developed into the plantain 
forms. The writer has not succeeded in making such transfers, but in 
1915 an infestation of this aphid was found on a Northern Spy on August 5. 
At that time only a few leaves were infested, and developing young, 
both winged and wingless, were present. This infestation became severe 
by August 25, but shortly thereafter all the aphids transformed to winged 
individuals and left the tree. Where this infestation came from is 
a mystery, as no lice had been present early in the season, and moreover 
the tree had been thoroly sprayed at least twice with Black-leaf-40 tobacco 
extract and soap. Neighboring apple trees had not a single plant louse 
present, nor did any lice appear later in the season. All about these 
trees there was a very abundant growth of narrow-leaved plantain, but 
no lice could be found on them at the time of the first appearance of 
the infestation on the Northern Spy tree. 
Habits of the migratory forms 
_ The spring migratory forms are very lively, and in the rearing cages 
they fly actively about, particularly in the bright sunshine. In the cages 
inclosed with cheesecloth they congregated in large numbers on the sunniest 
side and seemed very strongly attracted to the light. They would walk 
actively about, opening and shutting their wings, and seemed to be tip- 
toeing gently across the cloth in a very nervous manner. Gradually they 
discovered the narrow-leaved plantains in the cages (Plate VIII) and 
settled on them. Altho several broad-leaved plantains were also present 
they left these alone. Usually within from two to three days these winged 
forms began producing young, and then they became much more quies- 
cent while their broods of young congregated closely about them. 
