Pachypsylla venusta

Gall: Occurs at junction of leaf blade and petiole, spherical on C. laevigata, sometimes irregularly shaped and lobed on C. reticulata especially in western Texas, outer covering open above forming a cavity over the cells; polythalmic with 1-30 cells, average about 6; size from 3 mm to over 2 cm. The structure of this species and its large size permits it to be readily distinguished from the other species of Pachypsylla. Its galls are so regularly present and abundant in Central Texas that they are practically a key feature for the hackberries of this region. Since, however, it is not common in the northern states where most work on Pachypsylla has been carried out only incidental notes have appeared In the literature concerning its biology.

Range: Tuthill (1943) states that P. venusta was known at that time from Iowa, Kansas, Colorado, Texas, New Mexico, Ohio, Mississippi, Tennessee, North Carolina, New Jersey, and Con-necticut. Wells (1914), however, stated that he had not seen this species in Ohio, and Caldwell (1938) listed only one locality for this state. Moser (1958) did not find it in New York and apparently not in Ohio.

Pachypsylla venusta

Pachypsylla celtidisgrandis
Pachypsylla tridentata

Hosts: Celtis occidentalis, tenuifolia, laevigata, reticulata

Galls spherical and large (1-3 cm) on petiole, usually polythalamous

All over the hosts ranges, northeast to CT, southwest to AZ, UT, southeast to Georgia, northwest to ID.

Pachypsylla venusta (Fig 8)

on petioles, several compartments

Pachypsylla venusta

Generally globular, but often more or less irregularly ovoid, or even elongate. Color varying from pale buff to brown; surface opaque, with scattered, small, flattened postules. Diameter of globular form varying from 7 to 20mm, The gall consists of an outer shell and an inner core, which can easily be separated upon cutting the gall open. The outer shell is very hard and woody, varying in thickness from 1 to 3 mm. The apical portion of the gall has on one side a slit which is deepest and widest at the tip and connects here with the funnel-like, twisted, basal portion of the leaf. This slit exposes to view the inner core, which consists of the very thin and brittle walls of the irregular cells which fill the entire cavity of the outer shell. The number of these cells varies according to the size of the gall, but is rarely reduced to a single one.

The full-grown pupa always leaves the gall through the apical opening, and in doing so has to saw its way out through the top of the inner core.

The gall usually occupies the entire petiole, but in rare instances a small portion of the latter is visible between the gall and the twig.

Pachypsylla venusta

Reniform, large, petiole gall involving the base of the leaf and with an opening, polythalamous.

Pachypsylla venusta (Osten-Sacken) 1861

Psylla venusta Osten-Sacken, 1861. Entomol. Zeit. Stettin 22:422
Pachypsylla celtidis-venusta: [sic] Riley, 1883. Can. Entomol. 15:157-158;fig. 6.
Psylla celtidis-grandis Riley, 1883. Can. Entomol. 15:157; fig. 6.
Pachypsylla venusta: Riley, 1885. Proc. Biol. Soc. Wash. 2:72.
Pachypsylla tridentata Patch, 1912. Maine Agric. Exp. Sta. Bull. 202:224; fig.415 [synonymized by Crawford, 1914:110].

Pachypsylla venusta

Psylla venusta
Psylla celtidis-grandis
Pachypsylla tridentata

The galls are large (ave 1 to 1.5 cm in diameter), more or less spherical, not completely closed on one side and form on the leaf petioles. They remain attached to the tree usually, the mature insects emerging in the spring when the temperature becomes sufficiently high. They may be brought out during the winter by bringing them into a warm room. The last stadium nymph crawls from the gall and emerges as the adult very shortly thereafter. The galls are polythalamous.

Known from Iowa, Kansas, Colorado, Texas. New Mexico Ohio Mississippi, Tennessee, North. Carolina, New Jersey, and Connecticut: It is undoubtedly much more widespread throughout the range of its host

Pachypsylla venusta

This gall is a large, hard, asymmetrical, pear-shaped modification of the petiole, variable in size according to the number of chambers found in the gall; the chamber number being directly related to the number of insects concerned in the formation of one gall 1-2.5 cm. long, 8 mm. -18 mm. wide. Surface minutely roughened, destitute of hairs. Yellowish gray to brownish in color. At one side, near the distal end of the gall is always a prominent concavity which is apt to be bordered by the remnants of the leaf blade. Interiorly, radiating from a central core, the walls give rise to conic chambers (PI. XVI, Fig. 7a). This core, however, is attached directly to the wall of the sunken area or sinus, above mentioned. These chambers vary in number from 3 to 14. The radiating walls are very thin near the periphery where they join the hard outer shelL Fig. 7b shows the gall with the side removed. The chambers are nearly filled with a white, flocculent, waxen mass, a secretion of the nymphs. The pupae all emerge through the thin wall of the sunken area in the fall, and after the last ecdysis the insects fly to the bark, where they spend the winter. These galls are not common, the writer's entire collection numbering but a half dozen. They have not been seen in Ohio.

Pachypsylla venusta (Osten-Saken, 1861)

Diagnosis. This species is easy to recognize, because it is relatively much larger than the others. It makes large galls in the petioles of the leaves.
Distribution. Widely distributed in the eastern and central USA (Hodkinson 1988).
Host plants. Celtis laevigata Willd., C. occidentalis L. (Cannabaceae)