Celticecis celtiphyllia

Celticecis wellsi

Celticecis globosa

Celticecis oviformis

Celticecis pyriformis

Celticecis semenrumicis

Celticecis spiniformis

Celticecis supina

Pachypsylla celtidisvesicula

Aceria celtis

Agromyza deserta

Pachypsylla celtidisgemma

Pachypsylla celtidismamma

Pachypsylla venusta

Celticecis expulsa

Pachypsylla celtidisinteneris

Proteoteras aesculana

Phytophaga celtiphyllia Felt

A sub-balloon-shaped gall occurring on the leaves (either side), petioles and stems. 4-8 mm high, including the apical, variable, attenuate tip, which arises sharply from the distal end of the gall body. 4-5.5 mm. dia. through the broad distal half of the gall. The sides do not taper proximally in the typical balloon fashion, but show a definite constriction below the distal expanded portion. When isolated the galls show a perfect radially symmetric structure, but they are apt to be found in clusters, resulting in more or less loss of symmetry through mutual pressure. When on the leaves they generally are found on the upper side attached close to the principal veins. These galls retain their green color longer than any of the others ; when full size in mid-summer, the content of chloroplasts in the superficial cell layers is so great as to make them fully as green as the leaf. Coarsely pubescent. The chamber is constricted distally. Galls not uncommon in Kansas, but this form has not been seen in Ohio. 

The writer is practically certain that this is the gall described by Pergande, whose notes are presented by Felt with the description of the above insect. Pergande states it to be a "very hard, obconic gall, the upper extremity produced as a long slender nipple; at the base five or six low ridges. The galls occur on the upper side of the leaf and drop when mature." Unfortunately no measurements are given. On the basis of the brief description, however, absolute certainty is not possible. 

Phytophaga wellsi Felt. Cecidium nov.

On leaf, under side, more or less definitely obconic, resembling the shape of a somewhat flattened top. Generally found in clusters attached to the sides of the principal veins near the point of their divergence from the petiole. 2.5-3 mm. high, 3-4 mm. wide. Distal end shows a more or less definite central prominence. Yellowish tinged, with short pubescence. Walls pithy in texture, yet firm; tissue when old, brown. Chamber sub-cylindric. Protective layer poorly developed, confined to proximal one-third of gall. Nutritive layer very thin. Fibro-vascular bundles traverse galls near the surface. This is the simplest of all the itonid galls studied. 

12. Cecidomyia sp.

"On leaf, under side, stoutly conical and nippled at tip. Succulent, pale green, and covered with fine bloom when young. 3x4 mm. Present in great numbers; larva, white." Sears. 

The author's specimens rarely go over 3 mm. in high. They vary from 2-3 mm. in width. Many are purplish tinged. The chamber is sub-cylindric. rounded below. The protective layer is well developed and extends distally as far as the inner opening of the apical canal. The nutritive layer is confined to the proximal half of the chamber wall. The fibro-vascular bundles pass upward close to the protective layer. 

14. Cecidomyia sp. 

A large, globular, mucronate tipped gall of the stem. 5-8 mm. dia. Base varies toward a truncate condition in some specimens. Green throughout the summer; finely pubescent. Chamber large, spherical. A thin membrane is constructed by the larva across the distal end of the chamber. Protective layer thick, nearly half as thick as the wall. Does not extend to apical canal. Nutritive layer relatively thin. The fibro-vascular bundles traverse the protective layer. 

Riley describes a globular gall, which on "detaching the gall, the base is seen to be truncate and attached to the rib of the leaf by an extremely short, conical style, which is not visible from the sides. Average height, 3.5 mm., dia. at middle, 3.5-4 mm." See No. 32 in Riley's list [Celticecis pubescens]. This gall might be interpreted as an immature specimen of the above [Wells' Cecidomyia sp 13, Celticecis pyriformis]. Sear's number 34 is a variation of the above with the basal one-third developing low irregular ridges. 

13. Cecidomyia sp. 

"Leaf gall, present in great numbers on under side. A "peg-shaped" gall, cylindrical when young, and developing a thickened base as it grows. Pale green, straggling hirsute, 2-3 mm. long. Very common." Sears. 

The broad, ill-defined ridges which characterize the base of this gall separates it from all others. The protective layer is relatively thick, but does not extend into the wall of the distal end. The nutritive layer is thin. The fibro-vascular bundles pass through the parenchyma basally but approach the protective layer apically. Young specimens of this gall would closely approximate the gall described in Riley's report under No. 30 [Celticecis oviformis]. The expanded condition of the base is not gained until the gall has nearly completed its growth in length. 

15. Cecidomyia sp. (PI. XVII, Figs. 15, 15a, 15b.) This gall exhibits a remarkable variation from the previously described simpler types. Riley, who first described it, gave a very complete description of it, which will be quoted. "31. Galls on the tender twigs, occurring either singly or in groups of two, three or four or more specimens; rarely also singly on the under side or even the upper side of the leaf. The gall bears a close resemblance to the winged seed capsule (achenium) of a Rumex, but the wings vary in number from three to five and are often irregularly developed, while the tip always ends in a curved, long spine. The wings terminate in a sharp ridge which is sometimes double. Gall opaque, not hairy. Color pale-yellowish green, at apical third usually of a more decided green and darker. A longitudinal section reveals a single large regularly ovoid cell surrounded by a thin hard wall. Average height of gall, 4.5 mm., excluding the apical spine; generally as wide as high; length of apical spine variable, but usually a little more than half the height of the gall." Riley. 

The histology presents some points of special interest. The fibro-vascular bundles are found in the edge of the wings (PI. XVII, Fig. 15b), from which branches are distributed inwardly to the protective layer. This is better shown in the longitudinal section. Fig. 15a. The protective layer is found, as in most of the preceding galls, to be confined to the proximal two-thirds or three-fourths of the chamber wall. Trichomes line the apical canal to the point where it opens in the chamber. 

Cecidomyia unguicola

On leaf, under side, a, sharply pointed cone-shaped gall with flaring base. 3-5 mm. high, 2-3 mm. wide. Light green to yellow in color. Smooth, almost shining. Monothalamous, rarely, if ever confluent. Chamber sub-cylindric, with the distal half thinner walled than the proximal. The distal one- third or one-fourth of the gall is delimited proximally by the sudden transition from delicate sub-hyaline tissue to opaque hard tissue. Sooner or later the tip breaks off at this point. Riley states that "while issuing the perfect insect pushes off the tip." This gall is the most common of all the itonid galls of the hackberry; a hundred may often be found upon a single leaf.

11. Cecidomyia sp. (PI. XVII, Figs. 11, 11a). On leaf, under side, a small (2-3 mm. long, 1-1.5 mm. wide) sub-cylindric gall with attenuate tip, which is more or less definitely constricted from the body of the gall. Base rounded, light green to yellow, smooth. Thin walled, the chamber approximating the shape of the gall. The galls are commonly tilted over at a sharp angle, particularly when they arise from one of the larger veins. The protective and nutritive layers are distributed much as those of No. 7. Riley first described this gall (No. 35 in his paper [Gagne contradicts this, placing Riley's 35 as C pyriformis]) and called attention to its similarity to C. unguicola Beut. (See No. 8). It differs constantly from that gall, however, in its smaller size and its non-flaring base. 

Pachypsylla vesiculum

This, the simplest of the psyllid galls, is a small (2-3 mm. dia.) monothalamous "blister" gall of the intervenal tissue, commonly found close to the principal veins of the leaf. They are apt to occur in great numbers. More or less evenly convex above; a small, rounded central papilla can be determined below. The galls, both above and below, become lighter in color than the normal leaf, though very green when young. Easily evident from the latter part of May on through the summer. 

Eriophyes sp. 

This gall, a typical witches-broom, (PI. XIX, Fig. 1) represents a more or less serious disturbance of growth at the nodes. An excessive number (2 or 3 generally) of abnormal (wood reduced, pith increased) branches are produced from the same bud, followed by the development of an indefinite number of buds, all closely sessile in a mass at the node between the "gall" branches (PL XIII, Fig. 1). The subsequent infection of the basal buds of the new branches, the buds nearest to the original node attacked, accounts in great part for the characteristic irregular massing of the branches. If a young "broom" be stripped of its bark, (PL XIII, Fig. la), this relation of the primary and secondary branches is made evident. Often, however, in later years, buds located at the base of the primary "gall" branches will develop a shoot. After a number of years the mass of branches becomes so large as to be very conspicuous and unsightly. The author has investigated new branches growing on old galls without finding any mites. It seems probable that the condition of things grows worse after the primary infection, whether or not the mites are present. The gall proper is altogether confined to the nodes affected, in which region two prominent facts stand out in relation to the histology of the parts affected: (1) The bases of the gall branches have suffered an inhibition of their differentiation; (2) The cortex shows definite hyperplasia. These facts are shown in PL XIII, Fig. Ic, which illustrates the longitudinal section of the part indicated at c, in Fig. la, which is a longitudinal, median section through a primary "gall" branch and the normal twig, from which it has grown out. 

Kellerman and Swingle (12, 13) have associated a fungus (Sphaerotheca phytoptophila Kell. and Sw.) with this gall. No mycelium was seen in the affected tissues; indeed none would be expected belonging to the fungus named, since its position among the Erysiphaceas would indicate it to be wholly superficial, the haustoria only affecting epidermal cells. Other well known witches-brooms, particularly those of Europe, have been shown to be caused by mites only. 

Lepidopteron (species undetermined) [this entry is included on the basis of the similarity of the gall; no formal assertion that this is the same species is known] 

This gall, (PI. XIX, Fig. 2) is an aborted shoot from a lateral bud, developing very rapidly in the early spring, reaching its full size (in Kansas) toward the end of April. 1.5 ~ 3 cm. long, 4-6 mm. wide. The nodes near the end of the gall bear small leaves which die early. Affected stems either smooth or pubescent. The larva finishes feeding on the central part of the galled twig and leaves the structure during the early part of May. It always eats out a circular hole near the base to make its exit. (PI. XIII, Fig. 2 a). The gall soon after turns brown and drops from the parent branch. 

Patton (26) has described a "hollow, elongate, twig swelling" from which he states cecidomyidous flies emerged "about the middle of June." From his brief description it is impossible to state whether his gall is the same as the one here described. The flies noted might have been parasitic on the lepidopteron. 

Riley reports a tortricid, Proteoteras aesculana Riley, occurring on the hackberry. No mention of any gall is made, however, in connection with this tree, other than that the larvae were found "on short twigs." On the buckeye and maple it "bores in the terminal green twigs, producing a swelling or pseudo-gall." (See Am. Nat. cit. below). This may be the insect concerned in the production of the lepidopterous gall herewith described, but from this mere suggestion of its gall forming habit, it is impossible to be certain. 

Pachypsylla gemma Riley. Figure 5

As indicated in the specific name of the insect, this is a gall of the bud. The bud incept suffers extreme modification in its development, an irregular sub-spherical structure being formed, containing from three to eight chambers. When the chambers are numerous the structure takes on a nodular aspect. 3-5 mm. long, 4-5 mm. wide. In many specimens faint outlines are present, suggesting the normal scale structure, though in no case are free scales present. The color is lighter than that of the normal buds. Very common. 

This gall differs from the preceding in that it is uniformly polythalamous and always projects from the stem as a definite (appendicular) modification of the bud. The protective layer does not occur immediately beneath a cork layer, but differentiates beneath a thick zone of tissue, which can be interpreted as the homolog of the outer bud scale. Fundamentally, however, the two galls are similar and they eventually may be shown to be caused by the same species of psyllid. They are here separated for the reason that no transition forms between them have been observed. 

Pachypsylla mamma

A short, sub-cylindric gall on the under side of the leaf, 5-8 mm. high, 4.5-5.5 mm. wide at base, almost uniformly arising near a principal vein. The distal end varies from a definitely smaller diameter than that at the base, to a noticeably larger diameter, in the first case the galls are sub-conic with rounded ends, in the second, sub-balloon-shape, with the ends more flattened. On the upper side of the leaf is a conspicuous circular depression or basin, in the center of which a minute conic papilla is evident. This papilla is part of the first gall tissue developed, being the cone which grew up around the larva in the process of embedding it in the leaf tissue. In color the galls are light green, varying to violet and purple tints. Most specimens show a definite bluish bloom. The adult galls are smooth, though when very young they are covered with an array of long acicular trichomes. The galls when fully mature show interiorly a dome-shaped cavity, which extends to the very base of the gall. This cavity is developed through the dehiscence of the middle tissue of the nutritive layer. A secondary chamber, variable in size, though much smaller, is found in the region beneath the papilla. It represents the failure of the tissue above the larva to grow completely together. The walls are firm and brittle. The insects leave the gall about the time of the first frost and as imagoes spend the winter concealed in the bark of the tree. The galls are more or less abundant on hackberry trees everywhere. 

The discovery of the central, extremely narrow pit or canal in the distal half of this gall, makes it possible to correlate it to such varietal forms as Riley's P. curcurbita, which is smaller and presents a prominent, wide, yet deep, apical pit. If P. curcurbita should ultimately be shown to be a distinct species, it would as such form a transition type between P. vesiculum and P. mamma, though it stands closer to the latter than the former. One P. mamma gall studied failed to exhibit the presence of the distal pit. 

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. 

Cecidomyia sp. Cecidium nov. 

A gall of the leaves, stem, petiole or fruit occurring generally in an aggregate condition. An isolated specimen on the stem will be described to elucidate the fundamental unit characteristics (PI. XVIII, Figs. 16, 16a). When found singly, the gall is irregularly conic or sub-cylindric, with a very blunt truncate tip. The chief character is involved in the fact that the gall eventually drops its larval chamber enclosed by the nutritive and protective layers. This central part of the gall which slips out has the shape of a short, blunt horn. The tapering of this structure toward the proximal part of the gall makes possible the easy departure of this larva containing portion when the dehiscence layer surrounding it gives way. The gall aggregates commonly occur at or near the end of the stem, the tissue, after the larval chambers have fallen, dying, turning black, giving the twig an unsightly appearance (PI. XIX, Fig. 6). In the case of a single gall (PI. XIX, Fig. 4) the stem is not killed, but the tissue of the "socket" part is cut off by an abscission layer (Fig. 16a, PI. XVIII). 

The gall on the fruit (PI. XIX, Fig. 8) possesses exactly the same structure as those on other parts of the plant. The galls shown are not mature, the chamber not having burst through the surrounding supporting tissue. In section (PI. XIX Fig. 4) the galls are seen to project into the ovulary cavity, exhibiting in their entirety the characteristic shape observed in those of the leaf which project from both sides of the leaf. The ovule is aborted. 

Pachypsylla sp. (gemma? see next) Figure 4

This gall is a lateral, oval swelling of the stem, generally found near or involving the nodal region. 5-7 mm. long, 2.5-3.5 mm. wide. Color and surface texture that of the normal bark. Predominately monothalamous ; confluent cases occur forming a two-chambered and even a three-chambered gall. Very common on the terminal twigs of the hackberry. Remnants of old galls can be made out on stems 5-10 years old. The galls are commonly torn open by birds to obtain the soft insects within, which spend the winter in the galls. One of these nymphs is shown on the gall (PI. XIX, Fig. 3). 

It is not definitely known whether the imagoes from this gall and those from the next, P. gemma, are identical. The nymphs appear to be identical. The galls, however, are distinct, a difference, however, which may be referable to the plant part affected rather than to any specific behavior on the part of the insects respectively. This matter will be explained after P. gemma has been described. 

This gall started in a similar manner to that of P. vesiculum, by the larva inducing a cone of tissue to grow over it, burying it in the superficial layer of the young stem. This minute cone early becomes obliterated. 

The comparative morphology of the zoocecidia of Celtis occidentalis