Amphibolips confluenta

Zopheroteras compressum (agamic)

Liposthenes glechomae

Diplolepis rosae

Diplolepis ignota

Neuroterus quercusbatatus (sexgen)

Neuroterus quercusbatatus (agamic)

Neuroterus quercusbatatus (agamic) (q-bicolor)

Neuroterus quercusbatatus (sexgen) (q-bicolor)

Neuroterus tectus (sexgen)

Callirhytis quercusfutilis (sexgen)

Callirhytis quercusfutilis (agamic)

Callirhytis quercusoperator (sexgen)

Callirhytis quercusoperator (agamic)

Dryocosmus quercuspalustris (sexgen)

Acraspis erinacei (sexgen)

Acraspis erinacei (agamic)

Amphibolips confluens

B.D. Walsh (1864) had reported in great detail the discovery of two very different forms of adults, one agamic and the other bisexual, emerging at different times of the year from very similar if not identical galls of Amphibolips confluens. The work was undoubtedly exact as far as it went and, if it covers the complete life cycle of the species, it furnishes the first completed record of alternation. But Walsh, though he attempted to control the insects by confining them in nets placed on the trees, was unable to discover oviposition and it is not yet satisfactorily shown that the complete life cycle of the species has been discovered. 

Andricus palustris form compressus (Gillette)

Acraspis compressus Gillette, 1891, Bull. 111. Lab. Nat. Hist., Ill, p. 197. 
Acraspis compressa Dalla Torre, 1893, Cat. Hymen., Cynip., II, p. 64. Dalla Torre and Kieffer, 1902, Gen. Ins., Hymen., Cynip., p.. 58. Dalla Torre and Kieffer, 1910, Das Tierreich, XXIV, p. 409. 
Philonix compressa Beutenmuller, 1909, Bull. Amer. Mus. Nat. Hist., XXVI, p. 253. Felt, 1918, N. Y. State Mus. Bull., CC, p. 94. 
Acraspis compressum Thompson, 1915, Cat. Amer. Ins. Galls., pp. 15, 35, PI. iv, fig. 78. 

Galls. — Small, globular galls, (Figs. 25 and 26), 2-3 mm. in diameter, very slightly attached to the under surfaces (rarely the upper surfaces) of the leaves by a slight projection on the gall. White or pinkish, wax-like, solid and succulent at first, quickly deciduous, after which the gall enlarges and becomes brown, thin-walled, and hollow, the cavity constituting the larval cell. On the same species of red oaks, most likely, as the palustris gall.

These minute galls are very quickly deciduous, falling in October or early November, usually before the leaves, to the ground where they undergo further development. The larva does not pupate until the next spring, a little time before emerging in April or early May, just before the time of appearance of palustris galls. 

The adults [of Dryocosmus quercuspalustris, Kinsey's purported alternate generation] emerge from mid-May to June 4, depending on the latitude and the progress of the season. The insects are produced in about equal numbers of the sexes. They copulate almost immediately upon emergence and run rapidly up the branches to the young leaves, on the under sides of which they settle to oviposit, often remaining there for several days before they die. In all, only about a month has passed from the time of the first appearance of the young gall to the time of oviposition. Over ten months will be required for the alternate generation to reach full maturity. 

The experiments by which I was fortunate enough to discover the relations of the two generations of this species were made under the strictly controlled conditions which I have described in the introduction. The tree on which the sexual adults were put was covered with a net for almost a month and there was no chance of other insects having reached it during that time, nor is there much likelihood of the galls having been produced by insects from any other source. Of the thirty small oaks in the greenhouse, none produced any galls that season (1918) except the one on which the palustris had been isolated. Several scores of the adults of that form were observed to oviposit on the under surface of the leaves on which eight galls of Philonix compressa were found the first of September. The small size of the galls had prevented their detection earlier, for it is likely that they appear by the first of August. 

P. compressa was a '‘species’' known definitely from only two stations, Westchester Co., N. Y., and Ames, Iowa, while palustris had been known for sixty years to be a very abundant species throughout eastern America. It was rather surprising to find an apparently rare, local species to be the alternate form of one of the commonest of widely distributed galls. Fortunately, I recalled definitely the location of the very trees on which I had found the palustris galls from which the experimental material had been bred. I made a trip to these trees and found the leaves bearing an abundance of the compressa galls. Then I found the galls in the Millett Thompson Collection, taken in Massachusetts or lthode Island; these were figured in the Thompson Catalogue but the collection was not recorded in the text. After that, I collected compressa galls at Melrose Highlands, Forest Hills, and Blue Hills, which are in the neighborhood of Boston, and always found it abundant at that date. The small size of the galls and the fact that they are very quickly deciduous is sufficient explanation of the failure of previous collectors to find the form. 

Aylax glechomae

Hosts: Glechoma hederacea

Galls. — Rounded galls (Figs. 1 and 2) on the leaves, petioles, or stems of Nepeta (Glechoma) hederacea, the ground-ivy (gill-over-the-ground). Monothalamous, or several galls fused. Each gall is 6-12 mm., more or less, in diameter, rounded, covered with a rather dense, stiff pubescence, reddish and green when young; when old becoming dry, brown, smooth, with a thin, papery covering separating more or less or entirely lost from the gall during the winter. The larval cell is central, held in place by rather abundant, very irregular, coarse fibers. 

Range: Europe. ME, MA, CT, NY, NJ, OH, IN, IL

Mayr first pointed out the synonymy of the European glechomae and Bassett's similis. The species was undoubtedly introduced into America from Europe, for its host, the ground-ivy, is of European origin.

The galls appear in late May or early June. In this young condition they are eaten in France. The galls mature in late July and, as the plants begin dying off in September, the dried galls drop to the ground where they overwinter, being in large part decayed by springtime. The galls are heavily parasitized. The insects mature in the fall and overwinter as adults, not emerging, however, until the following April or May. Adler proved, by experimentally raising successive generations, that there is no alternation of generations with the species and, since the male is unknown, it is likely that reproduction is purely agamic, the eggs never being fertilized. 

Rhodites rosae 

Cynips rosae
Diplolepis bedeguaris
Diplolepis rosae
Diplolepis bedeguaris fungosae

Hosts: Rosa rubiginosa; it has been recorded from eighteen species of rose, and is likely to be found on almost any of the species.

Gall. A large mass (Figs. 3 and 4) of moss-like filaments surrounding a cluster of hard, bud-like cells. The filaments are pale green or reddish or purplish- tinged when young, becoming brown or black during the winter; they are sometimes simple, forming a tangled mass, or may be broad, branched, or leaf-like; the whole gall is spherical or oval, about 50 mm. or less in diameter. Each cell of the central core is a modified bud, monothalamous, thick-walled, with a distinct but inseparable larval cell; the cell is more or less covered with irregular projections; and often several cells fuse. Terminal on the stems of roses, especially of the sweet briar; it has been recorded from eighteen species of rose, and is likely to be found on almost any of the species.

Range: Toronto, Quebec, New England to Georgia, west to Michigan, Kansas, and Colorado

The species is evidently of European origin, probably having been imported in North American and other parts of the world on the sweet-briar. 

The gall is a curious modification of the young leaves. It is among the most specialized of the Rhodites galls. But what has been gained by the specializaton is not altogether apparent, for the amount of parasitism of this species is great (at least 15%), and evidently the peculiar devices which complicate the gall are of no avail in keeping out parasitic insects. 

The galls of rosae appear as early as June 5 (Adler, 1877), about three weeks after the eggs are laid; these galls are well grown in late July and mature by September. The insects overwinter as larvae and pupate only a few days before their emergence from the gall. The adults emerge from April 27 to July 9. This is a wider range of dates of emergence than is commonly found among the Cynipidae and, unlike practically all of the other gall-wasps, adults of this species will sometimes emerge from a single gall at two or more dates separated by a month or more, indicating a considerable range of differences between the eggs from a single parent. The adults oviposit within a few hours after emergence but may live for four or five days before dying. 

Males and females are sometimes produced in about equal abundance. From my first lot of material I bred six females and seven males, and Cameron reported (1889) a similar experience. But other galls will give no males at all, indicating a great variation in the eggs laid by different individuals. The final average gives between one and two per cent males, and the observations of several workers (Adler, 1888; Cameron, 1889; et al.) confirm my experience in this respect. It is to be expected that under such conditions the females are often not fecundated but, nevertheless, the eggs of such individuals will grow parthenogenetically. This was very positively proved by Adler (1877), who secured galls from eggs he had observed to be laid in the plant. He conducted extensive experiments with this species; in four different years he obtained similar results, rearing three generations in direct succession, obtaining galls and adults in each case exactly like those of the parent generation. This was conclusive proof that there is no alternation of generations with this species, and nothing known of its life history would suggest that an alternation ever occurs. By strictly isolating the females from the males at emergence and before oviposition, and by anatomical examination of the receptaculum, Adler proved the parthenogenetic development of eggs. 

Rhodites ignotus

Rhodites ignota
Rhodites carolina
Rhodites carolinus

Galls. — Irregularly globose leaf-galls (Figs. 5 to 7), covered with a white, mealy powder. Each gall is about globose, monothalamous, but often several galls coalesce to form large, elongate, more or less entire masses sometimes 20 mm. long. On the terminal twigs, petioles, and stems of the leaflets of Rosa blanda, R. Carolina , R. humilis, R. nitida , R. virginiana, and most likely other roses. 

Range: Ontario, MA, RI, CT, NY, NJ, PA, MD, DC, NC, FL, IO, CO

The galls of Rhodites ignotus are first noticeable about the middle of August, somewhat deforming the leaves of the roses on which they are formed. The galls overwinter, sometimes on the bush, but often on the ground, to which they readily fall when the leaves bearing them wither in the autumn. The mature wasps are known to emerge the following spring from May to August, most of the adults appearing about the last of May or the first of June. As with R. rosae, this extended period of emergence is an unusual thing to find among the gall-wasps. Of thirty-seven of the wasps which I have bred, thirteen, i. e.. 35% of them were males, which is a higher percentage than that known from other species of the genus. However, incomplete observations on other breedings I have made would indicate a much lower percentage of males to be more nearly normal. The number of parasites obtained from these galls is extremely high : I have found them to constitute about 90% of all the insects bred — another instance of the ineffacacy of highly developed “protective” devices. Most of these parasites, are figitids, Synerginaj, etc , the so-called “inquilines,” but many other parasitic Hymenoptera also attack the galls. 

The adults of ignotus live for only a few days at the most, oviposition often occurring only a few hours after emergence. The females will refuse to oviposit unless they find a bush in the right condition for receiving the eggs. A lot of the insects which I placed on a cultivated rose which was somewhat retarded in development refused to climb over the bush at all to examine the buds, though the same insects became active enough when placed on a plant in a more advanced state of development. They carefully examined the young leaves, hardly yet out of the buds, and in these leaves the eggs were laid. The quantities of parasites which emerged, mostly a couple of weeks after the cynipids, were very active in examining the leaves of the same plant and many of them were observed to oviposit, but whether into the eggs and very young galls of the gall-wasps I am not certain. 

The points at which oviposition was made by the ignotus females were carefully marked and kept covered by gauze bags for almost a month and a half. The galls produced were first seen about the first of September, i. e., over a month and a half after the eggs were laid, but the degree of development of the galls indicated that they had appeared possibly two weeks earlier. The galls thus obtained were typical ignotus galls, in every way resembling the galls of the parent generation. Nothing else known of the life history of the species would suggest that it possesses an alternation of generations. Ants attacked the cynipids when they died after oviposition and only a single whole specimen, a male, was rescued for the collection. This, with galls of the two successive generations, are in my collections, distinctively labelled. I cannot say positively whether the reproduction is wholly or at any time parthenogenetic, though it is very likely that it is parthenogenetic at least part of the time. The one male in my net may have fertilized the fe- males, though I did not observe copulation. 

Neuroterus batatus form bisexualis, new name

Galls. — Moderate-sized swellings (Figs. 8 and 9) of young stems and petioles, essentially the same as the galls of the agamic generation (q. v.), but differing in being often much smaller, often having tufts of short, woolly pubescence. On stems, petioles, or midveins of Quercus alba. 

Range: Canada. NH, MA, RI, CT, NY, NJ, VA, OH, IL, MI, CO

In 1864 Bassett reported that he had observed for a number of years the alternation of two crops of galls on a small tree near his house. The abundance of each crop in turn suggested the relationships of the two. Moreover, the insects proved indistinguishable except through a slight difference in size and in the then unexpected condition of having- only females in the winter galls, with both males and females in about equal numbers from the spring galls. Neither Bassett nor later workers have actually seen the oviposition of the species, nor obtained under con- trolled conditions the gall of one generation from an egg deposited by a female of the previous generation, but Bassett’s field experience is regularly confirmed by later collectors of gall- wasps. I have examined material from the Bassett collection which shows this, also photographs of material collected by Miss Cora Clarke, and a quantity of material collected and bred by Millett T. Thompson. This latter material shows the two generations often close together on successive parts of the same branch. The descriptions here given are made from a study of many specimens which I have compared with the Bassett types. No previous separation has been made of descriptions of the two forms of adults, and the gall of the bisexual generation has never been described in detail, nor have Latin names been applied to distinguish the forms. 

The galls of the bisexual generations appear about the middle of May and the adults emerge, in about equal numbers of the sexes, by the middle of June. These oviposit in the new wood of the stem on which the better-known gall of the agamic generation develops. 

Neuroterus batatus form batatus

Galls. — Large, woody, stem swellings (Figs. 10 to 12). Polythalamous. Averaging 40X10 mm., often larger; tuber-like, irregular, but usually roughly cylindrical, elongate, involving stems and bases of petioles on terminal twigs; inseparable from the rest of the plant. Bark-colored, reddish, purplish brown, or with a glaucous bloom. Internally the galls are solid, woody, the larval cells scattered irregularly, the cell walls hardly distinct and not at all separable from the surrounding tissues. On terminal stems of Quercus alba (not known definitely from any other species of oak). 

Range: Canada. NH, MA, RI, CT, NY, NJ, VA, OH, IL, MI, CO

The galls of this generation, because they remain upon the tree for the longer time and often reach the larger size, are the better-known of the two forms of this species. The insects live in the galls over winter, emerging late the following April or early in May. The very great similarity of the adults of the two generations of this species (except for the agamy in the winter generation) and the essentially identical plan of the galls of the two forms, is a matter of great interest. In this species, as in Neuroterus noxiosus, we find as simple a case of alternation of generations as has yet been recognized. The differences in the galls are very evidently due to seasonal differences of the conditions in the part of the host affected. 

Neuroterus noxiosus form noxiosus

Galls. — Irregular, elongate, woody swellings (Figs. 17 to 19) of young stems and sometimes petioles. Polythalamous. About 60X10 mm., roughly cylindrical, but often very irregularly twisted, etc. Inseparable from the plant. Bark-colored, usually with a glaucous bloom. Internally the gall is closely packed with larval cells which are distinct but not separable from the surrounding woody tissue. On the newer growth of Quercus bicolor , Q. Prinus , and possibly other oaks. 

Range: MA, RI, CT, NY, NJ, New Brunswick, IL, IO, MI

This gall is the better-known form of the species, due apparently to its longer persistence on the tree. The gall very closely resembles that of Neuroterus batatus batatus, from specimens of which it is often difficult to distinguish this species. The more highly distinct larval cells of noxiosus is often a good basis for making the distinction. The most certain test, however, is the species of the host plant, noxiosus being confined as far as known to Quercus bicolor and Q. Prinus , while batatus occurs on Q. alba. It would prove interesting to try to induce one of these species to oviposit on the “wrong” species of oak, and to observe if galls and what galls were produced. The larvae of noxiosus overwinter in the galls, emerging the following spring from March 24 through April to early May. 

Neuroterus noxiosus form vernalis, new name

Galls. — Irregular clusters of woody swellings (Figs. 14 to 16) of the stems, petioles, and leaves. Polythalamous. The whole mass roughly about 20X40 mm. in diameter or less, inseparable from the plant; fist-like, the separate parts woody, indicating the separate leaves or parts of leaves involved, and bearing a small portion of deformed leaves; these parts are united by the deformed petiole, or by a fused mass of petioles or young twigs. The gall is bark-colored, or tinged with a glaucous bloom. Internally the larval cells are crowded closely together, the cells very distinct but not separable from the surrounding woody tissue. On the young growth of Quercus Prinus and Q. bicolor. 

Range: MA, RI, CT, NY, NJ, New Brunswick, IL, IO, MI

When Bassett first described this species he gave detailed descriptions of the galls of the two generations and noted differences in sizes of the adults. The specific relations of the two generations had been arrived at through the field observation of the alternate abundance of the two forms of galls and the close similarity of the adults of the successive generations. The tremendous abundance of this species locally often gives abundance opportunity for observations. Gillette, Beutenmuller, Miss Clarke, Thompson, and other students of the family have made observations confirming Bassett’s statements, and there can be no doubt of the regular alternation of these forms, even though the data has not been checked by experimental work. This was the fourth and last in- stance of heterogeny discovered by Bassett. 

The galls of this form appear when the young leaves first unfold in May and, like most of the spring galls of dimorphic species, grow very rapidly to maturity. The adults are known to emerge from June 12 to July 5. They occur in about equal numbers of the sexes: I counted 276 females and 233 males in one lot bred by Millett T. Thompson. After fertilization the females oviposit in the new wood of the twigs, usually not far from the galls in which they have developed. 

Neuroterus tectus form tectus [sexgen]

Galls. — Small swellings (Figs. 20 to 22) of the stems of flower clusters, of petioles, or of young stems of oak. Each swelling consists of closely-packed clusters of thin- walled, oval larval cells, each measuring about .7X1.2 mm. with a thin covering of distorted bark, there being little other hypertrophied tissue present. Usually covered with gray pubescence. On Quercus prinoides (and Q. alba?). 

Range: MA, CT, PA, RI, NY, NJ

These galls are very inconspicuous productions, hardly to be observed until the tiny exit holes made by the insects may be found in the stems of the flower clusters. The insects emerge late in May and early in June, after only a month spent in the galls. Bassett found the adults mostly emerged by June 10. 

Neuroterus tectus form abundans, new name [agamic]

Galls. — Not certainly identified. Most likely swellings very similar to the galls of the bisexual generation, but on the midvein of the young leaves, somewhat distorting the whole leaf. 

Range: MA, CT, PA, RI, NY, NJ

The eggs which produce this form of the species are laid early in June by the female of the bisexual generation. It is not certain what sort of galls are produced. Galls of the above description, in the Thompson Collection, belong, I believe, to the females of this generation, but the data was not distinctly affixed. From what is known of the life history of the species, it is evident that this generation lives in the galls for about ten and a half months, emerging and ovipositing April 29 (Bassett) to May 10 (Thompson). As far as known, the generation is agamic. The females very closely resemble the females of the bisexual generation but are readily distinguishable by the larger, more oval abdomen, a character to be expected in the agamic generation. 

The material on which I base this data was obtained by the late Millett T. Thompson, whose collection of gall-insects is now in the Museum of the Boston Society of Natural History. The females marked “F” in the collection were found ovipositing May 10, 1907, in buds of Quercus prinoides, the points of oviposition were marked, the galls produced were bred and the females and males of the bisexual generation obtained. This material, distinctively labelled, is now in the Boston Society collections and in the author’s collections. 

These observations are in accord with those made by Bassett concerning the similarity of the two generations as he had found them, but Bassett did not mark the points of oviposition of the agamic form, nor did he note the differences in the two generations and keep them sepa- rate in his collections. The female “tectus” as Bassett described it, was apparently the agamic female, but the description of the abdomen as “small, in outline an equilateral triangle,” applies distinctly to the female of the bisexual generation ; while among the Bassett cotypes are females of both generations. Inasmuch as the male and the distinctive gall of the bisexual generation were called tectus, I use that name to designate that generation, and abundans describing the larger-bodied female, for the agamic generation. 

I feel fortunate in being able to present the life history of this species, because it gives another instance of the very slight differences between the successive generations of the species of Neuroterus and, further, bears out my belief that alternation of generations is merely a development of seasonal dimorphism. It is very much to be desired that we closely observe other species of Neuroterus and try to discern still more primitive instances of dimorphism, or of a double-brooded condition without an accompanying heterogeny, among the species of the group. 

Andricus futilis form futilis

Cynips quercus futilis
Cynips quercus papillata
Cynips futilis
Cynips futiilis
Cynips papillata
Andricus papillata
Callirhytis futilis
Callirhytis papillatus
Andricus papillatus
Callirhytis papillata
Callirhytis quercus-futilis
Callirhytis quercus-papillata
Dryophanta papula

Galls. — Blister-like swellings (Figs. 28 and 29) of the leaf-blades, more or less globular, projecting only slightly on the upper surfaces, projecting in about half a hemisphere on the lower surfaces. Leaf-color, sometimes surrounded by a reddish ring on the surface of the leaf; about 3-7 mm. in diameter. Thin-shelled, hollow, with usually 2 or 3 small larval cells, distinct, central, connected with the outer wall of the gall by fine, silky, radiating fibers. On leaves of Quercus alba, Q. bicolor, Q. prinoides, Q. Prinus, and Q. stellata. 

Range: Ontario, NH, MA, CT, NY, NJ, PA, DC, MD, OH, IN, IL, MI

Osten Sacken did not feel certain of the specific differences of futilis and of papillatus ; the main reason for which the two have been kept distinct is the reddish ring sometimes found around the galls called papillatus, and the different host plants of the two. I have compared the types of the two species and believe them to be identical. At the most, papillatus may be a host variety of futilis. As far as I can discover, the female of this species has not been previously described. It is quite variable as to shade of coloring. 

The galls of futilis are first discernible about the middle of May, and are then to be found often very abundantly, on the white oak especially, sometimes occurring in numbers on a single leaf. The galls are at first so succulent that they are not easily bred; they should be gathered late in June and be placed directly on moist sand. The adults emerge from the last of June to the middle of July, leaving the empty galls now dry, hard, and brittle. The insects are positively geotropic and, after copulation, oviposit in the bark of the roots or the bases of the trunks of the white oaks. 

Andricus futilis form radicicola

Callirhytis radicis
Andricus radicicola
Andricus radicis

Galls. — Larval cells (Fig. 27) in the scurfy bark of the roots or the basal portions of the trunks of oaks. The cell-wall is distinct but inseparable from the surrounding bark-tissue which does not seem to have much new tissue developed, but is distorted to cover the larval cell, forming pustules about 3-4 mm. in diameter. On the same species of oak, most likely, on which futilis occurs. 

In 1873 Bassett reported finding a number of wasps of an unknown species ovipositing in the buds of white oaks, which trees bore, at a later date, quantities of the galls of futilis. This alone was not sufficient evidence to warrant conclusions, for futilis is often exceedingly abundant- on the majority of Q. alba trees in a region. But by 1889 he was able to report a more complete life history of the species. He had found hundreds of females which agreed with those he had bred from root-galls ovipositing in the buds of trees which later bore futilis-galls in abundance and only those galls. This evidence for the relation of the root-gall to the futilis-gall does not invite much doubt. The agamic form which had come from the root-galls was described as radids. 

The eggs which produce this form were laid in the bark during July. Because of the difficulty of finding these inconspicuous, subterranean galls, little is known of the form until it emerges as an adult the following spring, from April 22 to Arpil 25 and likely later. At such times they are often found ovipositing in the buds of the white oaks, on the new 7 leaves of which the futilis-galls will appear. 

In 1895 (Proc. Ent. Soc. Washington, III. p. 261) Riley reported the rearing of futilis galls by Pergande from buds which he had observed being pricked by several females of a cynipid w hich Ashmead identified as Callirhytis clavula. Riley suggested, therefoie, that Bassett/s observa- tions w r ere in error because of misidentification. On the other hand, it is to be noted that the value of Riley’s record depends on the correctness of Ashmead’s identification. I have carefully examined numbers of the very specimens on which Bassett based his report, and they are available to others who wish to study them. I cannot see any specific differences between the individuals bred from root-galls and those marked as ‘*ovi-positing in Q. alba buds, April 22, 1889.” Moreover, my own experience with C. clavula leads me to doubt the correctness of Riley's report. I know of no published dates of the emergence of that species but, having- collected many hundreds of the galls, examining them for enclosed larvae or adults regularly for a couple of years, I have found nothing to suggest that the imago emerges before the middle or last of July, at which time (July 27) I have been successful in obtaining several adults. Mr. Lewis R. Weld and Wm. Beutenmuller have kindly confirmed my experience by similar records from their own observations, July 12 to July 30 being the emergence dates from their breedings. It is not likely that Riley's insects, found ovipositing three months earlier than clavula emerges, could be that species. I have no doubt that there is an error in Riley’s report and that Bassett's observations of this species are correct. 

Range: Ontario, NH, MA, CT, NY, NJ, PA, DC, MD, OH, IN, IL, MI

Andricus operator form operator

Cynips quercus operator
Cynips operator
Andricus operator
Callirhytis operator
Callirhytis quercus-operator

Galls. — Large, compact masses (Fig. 32) of wool containing seed-like larval cells. The clusters are irregular in shape, often oval, 4X5.5 cm., more or less, in dimensions, the hairs at first crisp, succulent, greenish, white, or rose-tinged, some-times deep red, becoming yellowish brown with age, finally weathering bluish gray or black and drying into a shrivelled mass. Within the wool, scattered or in small clusters, are the larval cells, hard and rather thick-walled, oval, about 1.5X3 mm., distributed mostly but not entirely toward the center of the gall. On and involving the young terminal stems, new clusters of leaves, and especially the flower clusters of Quercus coccinea, Q. ilicifolia, Q. marylandica, Q. palustris, Q. rubra, Q. velutina, and likely related oaks. 

Range: Ontario, MA, RI, CT, NY, NJ, PA, DC, IL, New Brunswick

The gall of this form is a very abundant early-spring gall in scrub- oak country, appearing with the flowers of the oaks about the middle of May and growing rapidly. It should not be gathered for breeding until after the first of June, for it is succulent when first formed and dries and dies unless nearly mature when gathered. The woolly hairs, Bassett has pointed out, are merely a much modified leaf pubescence. The galls, after the emergence of the adults, become much the worse for weathering and by autumn only fragments of the wool remain upon the trees. The galls often bring great numbers of the insects to maturity; from three galls I obtained 578 adults which emerged from June 9 to June 30. The sexes are produced in about equal numbers. The females, as Bassett discovered, deposit the eggs in the acorns of the scrub-oaks, inserting the ovipositor between the nut and the cup of the very small, young acorns. The gall produced is the form operatola. 

Andricus operator form operatola

Cynips quercus operatola
Callirhytis operatola
Andricus operatola
Callirhytis operator
Andricus operator

Gall. — A small, seed-like gall (Figs. 30 and 31) at the base of the nut of the acorn, inside the cup. The gall suggests a development of the aborted ovule of the acorn, but sometimes five or six occur in a single acorn. It is a compressed, inverted cone in shape, about 5 mm. high by 4 mm. in diameter, larger or smaller, and is thin-walled, the larval cell occupying most of the gall. In the acorns of Quercus ilicifolia and of the other red oaks on which the bisexual form occurs. 

Range: Ontario, MA, RI, CT, NY, NJ, PA, DC, IL, New Brunswick

The most remarkable character of the heterogeny of this species really lies in the very great differences of the galls of the two generations, and even this does not appear so remarkable when one considers the totally different natures of the parts of the plant affected. 

The gall of operatola usually escapes detection until the fall, when the growing gall projects beyond the rim of the acorn cup and often splits or otherwise deforms the nut of the acorn. These galls fall to the ground, sometimes fixed in place, more often broken out of the fruit, so that acorns bearing the scars of the galls may be found abundantly under scrub-oaks. The galls are highly parasitized and are often much damaged by wintering on the ground — another instance of the poor quality of the “protection” afforded a gall-wasp. Consequently, it is a difficult matter to rear the adults of this form. Bassett states that the insects may mature the following spring or may remain in the galls until the second or even third spring before they emerge. He found them emerg- ing May 4 and ovipositing in the young buds of the oaks. 

Bassett’s observations of this species finally led to the first absolute proof that heterogeny occurred in the Cynipidae. A detailed account of the discovery has been given on page 324. Adults have been bred from galls of both generations and each of these have been observed to oviposit to produce the galls of the other generation. Bassett’s observations were apparently made in the open, but his definite statements would indicate that the pricked parts were definitely marked for later identification. 

Andricus palustris

Cynips quercus palustris
Cynips quercus notha
Andricus palustris
Andricus notha
Callirhytis notha
Callirhytis palustris
Dryophanta notha
Dryophanta palustris
Andricus pusulatoides
Neuroterus notha
Callirhytis pustulatoides
Callirhytis quercus-palustris
Callirhytis quercus-notha
Callirhytis pusulatoides
Cynips notha
Cynips quercus aquaticae
Spathegaster quercus laurifoliae
Andricus quercifoliae
Dryophanta liberaecellulae

Galls. — Globular, entirely hollow, succulent galls (Figs. 23 and 24) the size of a cherry, containing a free larval cell. The galls average about 3-12 mm. in diameter, are green or rose-tinged, very succulent, quickly shrivelling or decaying, and are entirely glabrous or in other instances roughened or densely but finely pubescent, depending upon the nature of the host. The mature gall is thin-walled, entirely hollow, more or less filled wuth a liquid, and contains a single larval cell, whitish, averaging 2.0 mm. in diameter, hard but thin- walled, entirely free, rolling about within the gall. Singly or in clusters, sometimes somewhat fused together, on the young buds, aments, petioles, and leaf-blades of oaks, sometimes only slightly attached, at other times inseparable from the leaf-tissue. On Quercus coccinea , Q. falcata, Q. ilicifolia, Q. imbricaria, Q. marilandica, Q. palustris, Q. phellos, Q. rubra , Q. velutina, and most likely other red oaks. 

Range: Ontario, MA, ME, RI, CT, NY, NJ, PA, DC

I have examined the types of Andricus notha (Osten Sacken) and the adults appear to be true palustris. The galls are somewhat more oval in shape, with the larval cell more elongate, but I have found that that character shows gradations in large series of palustris and there is little doubt that notha is, as Osten Sacken strongly suspicioned, not distinct. Beutenmuller makes Andricus pusulatoides Bassett a synonym of notha. Beutenmuller (1911, Bull. Amer. Mus. Nat. Hist., XXX) also says that he cannot find essential differences between true palustris and the types of Dryophanta aquaticae, D. laurifolice, and D. liberaecellulae but, because of lack of sufficient material, he prefers to consider them distinct. I can hardly see any justification for keeping those names out of the synonymy. 

The gall of Andricus palustris palustris is one of the best-known of the galls of early spring, appearing abundantly on red oaks of many species, often before any leaves have appeared. They often crowd closely on the flowers of the oaks. When the galls first appear they are solid, with the larval cell distinct but entirely connected with the outer walls of the gall; but within a very few days or even hours the gall, growing very rapidly, becomes hollow, leaving the larval cell (which had gained its full size in the young gall) loose to roll about within the enlarged outer wall at every movement of the branches of the tree. How the nourishment is provided for the larval cell and the enclosed larva is a process yet to be studied. During damp weather the galls will be found to contain a more or less viscous liquid, and placed in a pan of water they become filled with this liquid. It is probable that food is carried by osmosis to the larval chamber. Galls taken from the tree will grow still larger if placed directly on very moist sand or in water indicating how independent an organism these deformations may become. 

Because the galls are so very succulent they should not be gathered for breeding until they are about mature, and should then be placed directly on very moist sand. The growth of these galls is very rapid after their first appearance upon the trees and they are mature within ten days or two weeks. The pupation period of the insect is very short; within a few days the adult emerges and within another few days the galls are mostly completely withered away or have decayed. 

The adults emerge from mid-May to June 4, depending on the latitude and the progress of the season. The insects are produced in about equal numbers of the sexes. They copulate almost immediately upon emergence and run rapidly up the branches to the young leaves, on the under sides of which they settle to oviposit, often remaining there for several days before they die. In all, only about a month has passed from the time of the first appearance of the young gall to the time of oviposition. Over ten months will be required for the alternate generation to reach full maturity. 

The experiments by which I was fortunate enough to discover the relations of the two generations of this species were made under the strictly controlled conditions which I have described in the introduction. The tree on which the sexual adults were put was covered with a net for almost a month and there was no chance of other insects having reached it during that time, nor is there much likelihood of the galls having been produced by insects from any other source. Of the thirty small oaks in the greenhouse, none produced any galls that season (1918) except the one on which the palustris had been isolated. Several scores of the adults of that form were observed to oviposit on the under surface of the leaves on which eight galls of Philonix compressa were found the first of September. The small size of the galls had prevented their detection earlier, for it is likely that they appear by the first of August. 

P. compressa was a '‘species’' known definitely from only two stations, Westchester Co., N. Y., and Ames, Iowa, while palustris had been known for sixty years to be a very abundant species throughout eastern America. It was rather surprising to find an apparently rare, local species to be the alternate form of one of the commonest of widely distributed galls. Fortunately, I recalled definitely the location of the very trees on which I had found the palustris galls from which the experimental material had been bred. I made a trip to these trees and found the leaves bearing an abundance of the compressa galls. Then I found the galls in the Millett Thompson Collection, taken in Massachusetts or lthode Island; these were figured in the Thompson Catalogue but the collection was not recorded in the text. After that, I collected compressa galls at Melrose Highlands, Forest Hills, and Blue Hills, which are in the neighborhood of Boston, and always found it abundant at that date. The small size of the galls and the fact that they are very quickly deciduous is sufficient explanation of the failure of previous collectors to find the form. 

Andricus fulvicollis form bicolens

Dryophanta erinacei
Cynips erinacei

Galls. — Small, thin-walled, elongate egg-shaped galls (Fig. 33), within the bud-scales. The galls are about 2-3 mm. long, all but microscopically smooth, monothalamous, thin-walled, yellowish brown, without a separate or even distinct larval cell ; sometimes two or three galls will develop in the same bud-scale and become fused. In the bud-scales or (“bicolens”) on the terminal portions of leaf and flower buds of Quercus alba. 

Range: Ontario, MA, CT, NY, NJ, PA, VA, NC, FL, OH, IN, IL, MI, IO, KS, OK, CO [Kinsey places question marks by FL and CO indicating some doubt about these records]

In 1914 C. J. Triggerson reported from the Entomological Laboratory of Cornell University an account of the life history of this species, together with a study of its parasites and inquilines, and questions concerning the stimulus for gall formation. The observations on the life history of this wasp are more complete, and the evidence concerning the alternate generations more definite than for any other species of American cynipid, to date. Branches with buds in which the agamic form had oviposited were brought into the laboratory, where the adults of the second generation were bred from the galls. Oviposition of this generation was observed both in the laboratory and in the field, and later at these points galls of the agamic generation were obtained and the agamic female was again bred. Triggerson’s account furnishes many details of the life history of the species, and no attempt need be made here to give much more than descriptions of the galls and adults of the two generations. 

According to Triggerson, the galls of this form were first visible about May 12; the adults emerge from May 21 (indoors) or May 29 (out-of-doors) until June 5. They oviposit immediately to produce the agamic generation. 

Andricus fulvicollis form erinacei [Kinsey reverses the synonymy of fulvicollis and erinacei in later work]

Philonix fulvicollis 
Cynips quercus erinacei
Teras fulvicollis
Cynips fulvicollis
Acraspis erinacei
Biorhiza fulvicollis
Biorrhiza fulvicollis
Acraspis quercus-erinacei

Galls. — Oval leaf-galls (Fig. 34), densely covered with fine spines, reddish purple. The galls are globular or more often oval, 10X14 mm., more or less, the surface light yellowish, closely set with small, raised points, each tipped with a slender, thread like, flexuous spine 2 or 3 mm. long, yellowish, reddish purple, or blackish in color. Within, the tissue is compact-granular, the larval cells usually two or three (two to eight), each measuring about 1. 5X2.0 mm., the cells distinct but inseparable. Attached by a single point to a main-vein, on the upper or under surfaces of leaves of Quercus alba. 

Range: Ontario, MA, CT, NY, NJ, PA, VA, NC, FL, OH, IN, IL, MI, IO, KS, OK, CO [Kinsey places question marks by FL and CO indicating some doubt about these records]

Beutenmuller is authority for the identity of erinacei and fulvicollis. This gall appears in late June, becoming mature about the last of August, staying on the trees into October. The insects emerge from November 5 to 21. or even in early December, often when the weather is very cold, and snow is on the ground. The insect oviposits in the young buds of the oak trees. Fuller details of the habits of this species are given in Triggerson’s paper. 

Life histories of American Cynipidae