Pachypsylla venusta

Pachypsylla celtidismamma

Pachypsylla celtidisvesicula

Pachypsylla celtidisgemma

Pachypsylla celtidisinteneris

Pachypsylla pallida

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 celtidis-mamma

Psylla celtidis-mamma
Pachypsylla rohweri

 The, galls formed by this species occur on the leaves of hackberry, developmg into a more or less mammiform growth on the underside of the leaf. On the upper surface of the leaf a depression forms, cupping down into the gall. The shape of the gall itself is quite variable, often with a nipple-like tip, sometimes conical, glabrous or pubescent, etc. Usually they are monothalamous. 

The adults emerge in the fall, overinter in crevices of bark, etc.; early In the spring they fly to the twigs, and after mating, the females begin to deposit eggs about as soon as the leaves begin to appear. The nymphs feed on the lower side of the leaves and are soon enclosed in the fall. There is but one generation per year, the nymphs reaching maturity in September.

The type of Pachypsylla rohweri Cockerell (No. 18476) is in the Natronal Museum and is m my opinion identical with celtidis-mamma

Riley, apparently assuming that the shape of a  gall was an extremely accurate and highly constant specific character (even more so than the structure of the insect) proposed names for a species of Pachypsylla for each different shape of gall that he found. With these names he described the galls in detail but made no mention whatsoever of the insects. In a. preliminary statement, however, he said "the yet undescnbed species are all so closely allied to P. c-mamma that they can only be distinguished with difficulty." Elsewhere (Can. Ent. 15: 158) he says of one of them "P. c-mamma so closely resembles another species (P. c-cucurbita M. S. mihi), however, that without the galls it would be difficult if not impossible to separate them-a not uncommon occurrence among gall-making species." Anyone rearing these insects from the galls and not blinded by the above assumption of infallible gall specificity must soon come to the conclusions reached by Mally (1849) that, the shape and size of the gall is not at all constant .  .  . It was found that P. c.-mamma occurred in all the different variations, thus showing that these variations are not of specific importance." Fortunately, the series of names proposed by Riley stand as nomina nuda. Some few of them have cluttered up the literature of galls, however, and do until the present time. 

I have seen specimens of this very abundant animal from, or definIte records are available of its occurrence in, the following states and provinces: Colorado, Texas, Arizona, Utah, Oklahoma, Kansas, Nebraska, Iowa, Minnesota, Illinois, Indiana, Ohio, North Carolina, New Jersey, New York, Connecticut, and Ontario. It undoubtedly occurs, however, throughout the range of Its host species, hackberry (Celtis occidentalis L.).

Pachypsylla celtidis-vesicula

Pachypsylla celtidis-vesiculum

The gall formed on the leaves of the hackberry is of a quite different type from that of celtidis-mamma; it is blister-like and more prominent on the upper than on the lower surface. Very many galls are frequently found on the same leaf, and they are found on the same leaf with celtidis-mamma galls. This species is extremely abundant. It over-winters in the adult stage as does its relative and in company with it sometimes becomes a household nuisance in the fall. 

It is known from Iowa, Nebraska, Kansas, Oklahoma, Arizona, Louisiana, Ohio, New York, New Jersey, and Connecticut. It doubtlessly occurs throughout the range of its host (Celtis).

Pachypsylla celtidis-gemma

The adults appear in the spring (April and May in Iowa), having overwintered as nymphs in the galls. The galls are formed from the axillary buds on the twigs, usually they are polythalamous.

Specimens are at hand from Maryland, New Jersey, St. Catharine's Island, Georgia, Iowa, Nebraska, Kansas, Oklahoma, and Louisiana. It is also recorded from Virginia, District of Columbia, New York, Connecticut, Ohio, and Missouri. 

Pachypsylla celtidis-inteneris

Pachypsylla inteneris
Pachypsylla ungulata

The adults emerge in the spring from the galls which are located beneath the bark on the twigs or bases of the larger limbs.

Range: IO, IL, OH

Pachypsylla pallida

Numerous specimens are at hand from several localities in Arizona and New Mexico which seem undoubtedly to be this species. Two of them, from Organ Mountains, New Mexico, are accompanied by galls. The latter are on the twigs and appear to be very densely pubescent; on closer examination this pubescence seems to be a dense growth of sporangiophores of a white fungus, completely covering the galls. There is no evidence to indicate whether this is accidental or whether there is some significance to this association.

The Psyllids of America North of Mexico: (Psyllidae: Homoptera)