Phylloxera devastatrix

Hosts: Carya illinoinensis

Globular or irregular; about equally convex above and below; smooth; green, yellowish-green, or red on one side; diameter 3.0–15.0 mm; occurs on midvein of leaves, petioles, stems, leaf buds, and flower buds. Opening flat and round surrounded by pubescence or nipple-like and found below when present on leaf.

Stem, Leaf gall: globular

Range: AL, LA

Phylloxera devastatrix Pergande

Clusters of galls occur on young twigs, leaf petioles or flower stalks of Carya illinoensis in southern and south-eastern USA (Arkansas, Louisiana, Mississippi, Oklahoma, Texas), often causing serious economic damage. The galls are globular, of irregular shape, smooth, green or yellowish green with a reddish tinge before maturity, diameter 3-15 mm. They open in May-early June by means of a transverse split into four or more broad bracts, releasing alatae that immediately start to oviposit on neighbouring twigs, etc. There is no host alternation. The eggs develop into dwarf sexuales that mate and lay overwintering eggs under bark or at the base of the tree.

Phylloxera devastatrix

Carya sp.
Petiole or twig galls
Medium, growing in larger or smaller clusters and apparently deformations of flower and leaf buds, splitting when mature into four or more broad bracts, surface smooth, diameter 3 to 15 mm

Phylloxera devastatrix Pergande, n. sp

The galls of this species resemble very closely the smaller galls of caryaecaulis and also those of perniciosa. From both of these, however, the species differs markedly in the antennae of the winged form, which are much more slender than in either of the other two, with scarcely a constriction above the lower sensorium and with the anterior sensorium much shorter.

Its principal points of attack, as in the other species of this group, are the tender twigs, petioles and the midrib of the young leaves; but the leaf-buds and flower-buds are also often involved so as to prevent the setting of the fruit.

It appears to be an exclusively western or southwestern species, infesting the Pecan-hickory (Hicoria olivaeformis [Carya illinoiensis]) during May and early June. This gall was first received in 1887 from Mr. M. E. Winster of Staunton, Adams County, Miss., and again in 1889 from Mr. H. M. Johnson of Marston, LA., with the statement that it was greatly damaging the trees. It is either globular or more or less irregular in shape, especially where much crowded. Before opening it is often provided with a short more or less distinct nipple, most prominent in the younger galls, and becoming almost obsolete in the more mature form, when its position is indicated by a more or less densely pubescent spot. It splits transversely into four or more broad bracts, similar to those of caryaecaulis. The size varies from 3-15 mm. Surface smooth, green or yellowish-green, and often beautifully red on one side while young, turning brown or black and soon drying up after the architects have left.