Phylloxera caryae-fallax Riley.
Phylloxera caryae-fallax
Considerable doubt has existed until lately in my mind as to the identity of the species briefly referred to under this name by Walsh in his "First Ann. Rep. of the Nox. Ins. of Ills.," p. 23, and that described by Riley under the same name in the ' 'Seventh Ann. Rep. on the Nox. and Ben. Insects of Mo.," p. 118. Walsh states that he never found a winged insect either in this gall or in those of c. -semen and c- folia, though he has opened and examined hundreds of them. My observations regarding this peculiar gall, extending as far back as 1872, run counter to those of Walsh, for I have found this particular gall swarming with the winged female.
To account for this apparent discrepancy in independent observations, it may be stated that my own observations were made from early May until June, and that these made by Mr. Walsh were from the 17th until the end of June, or at a time when the winged form had already forsaken the galls. What, then, were the numerous larvae (?) with which he found the galls swarming, and what was their office? They could not well form new galls, as the season for that purpose was already too far advanced!
The explanation will doubtless be found in the following facts: If the galls be opened early in May, or before the nipple has opened, they will be found filled with winged insects, pupae, numerous eggs, and what appear to be larvae. These supposed larvae, however, upon careful examination, are not larvae hatched from eggs deposited by the stem-mother, but the true sexual individuals, both males and females, produced from eggs deposited freely by the winged females. In this species therefore, the sexed individuals are (in part at least) produced within the original gall, though . winged females subsequently perform the true function of migrants and leave the galls to carry their sexed young elsewhere.
The gall of this species is one of the most common and numerous on the leaves of Hicoria (Carya) alba, and probably some other species of the genus in the states of Missouri and Illinois, extending at least as far south as Tennessee and probably throughout most of the states bordering the Mississippi. It seems to be exclusively a western species, and is at times so extremely abundant as to cover completely every leaf upon a tree, the leaves becoming much dwarfed and distorted. On some small leaflets, about 2 inches long by 3/4 inch wide, more than 300 of these galls were counted.
The fully grown galls vary in height and diameter at base from 1-5 mm. Those more, densely crowded are narrower at base and higher in proportion. They are conical or tooth-like above and frequently lean over to one side. The under side is more or less prominently convex and more or less prolonged at the centre, with the nipple often, also, inclining to one side. The orifice is either round or oval, closely fringed with pale hairs, and tightly drawn together till maturity. The walls are rather tough and leathery. The color of the galls when younger is greenish-yellow to reddish, becoming gradually brown or black,- and brittle after the insects have left.
