Dryophanta erinacei (Mayr)

[of the agamic gall:] It is widely distributed, having been reported from New England, North Carolina, Iowa, Illinois, Indiana, Kansas, Michigan, Ohio, Virginia, Canada, and probably Florida and Colorado.

The [agamic] insect makes its way to the leaf and flower buds of the white oak, where oviposition takes place. On the tree where our observations were made, it continued to emerge and oviposit until the twenty-first of November.

Buds were examined on the eighth of May and the unhatched eggs found were very turgid, appearing slightly enlarged. On the twelfth of May a slight swelling, at the apex of which an empty egg shell was visible, appeared on the lower green portion of the scale, (Fig. 9, Pl II). This proved to be a freshly formed gall, containing a young larva of Dryophanta erinacei. The gall at this stage was thin-walled, with a pebbled surface, greenish in color, and contained a watery fluid. The egg-shell remains attached to the apex of the gall until the latter has reached considerable size, when it dries up and disappears. These hypertrophies develop rapidly, as many as three appearing on one scale. The wall of the gall has by this time changed to a yellowish brown color, and soon becomes quite dry and brittle.

Galls also develop on the apical portion of the leaf and flower buds, (Fig. 10, Pl II). These are red, being similar in color to the young leaf and flower. The wall is pebbled on the surface, and thin. The cavity contains a single larva bathed in a watery fluid, and similar in all respects to the one inhabiting the scale gall. The terminal galls are of the same size as those on the scales, varying in number from one to four, and when mature are reddish brown. Since only the agamic form of Dryophanta erinacei was found ovipositing on the leaf and flower buds, and since the eggs of this species and no other were found in the leaf and flower region, and since males and females similar in size and character emerge from the two galls, it is evident that they are produced by the same insect. The difference in color in the galls is due to the normal difference of the tissue of which they are formed.

Shoots were brought into the laboratory, placed in water and covered with bell jars. Here about noon on the twenty- first of May the first male and female emerged. They were quite vigorous, and about four-thirty in the afternoon the female was noticed actively moving along the midrib of the young leaf. Suddenly she stopped, and set up a rapid nodding motion which lasted thirty-five seconds, during which the ovipositor was thrust into the tissue. The insect remained motionless for a time, then withdrew the ovipositor, filling the passage with a yellow substance which, as in the agamic form, is probably a secretion poured forth by the accessory glands of the reproductive system. The process was repeated four times in succession without moving the body forward. Each time the ovipositor was inserted the body was curved slightly more than at the preceding puncture. The entire time occupied by the four ovipositions was from four-thirty- four to four-fifty, or sixteen minutes, thus allowing four minutes to each oviposition of which a little over two minutes and a half was occupied by the passage of the egg. Many other observations were made, and the time in all instances corresponded to the first recorded.

In the open the adults did not emerge until the twenty-ninth of May, and continued to oviposit from that time until the fifth of June.

Acraspis erinacei sex. gen.

Quercus alba
Bud galls
Fig 80. Thin-walled blister on the inner face of bud scales as buds start to open in the spring.

[Photo caption]

80. On Q alba. When the new growth elongates the affected bud scales are left adhering at its base. Developed winter buds on trees where the hedgehog gall was common the fall before and where the wingless agamic females were seen on Nov 1 ovipositing in the buds. Adults of both sexes emerged May 17 (Chi).

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.

Acraspis pezomachoides O.S.
var. erinacei Beutm.
Bisexual form, bicolens Kins.

Gall, seed-like, egg-shaped, in buds.

Adults, May.

On Q alba.

Cynips pezomachoides variety erinacei
bisexual form bicolens

Dryophanta erinacei
Cynips erinacei
Andricus fulvicollis form bicolens
Andricus erinacei bicolens
Acraspis erinacei
Diplolepis gemula err det Weld
Dryophanta erinacea

GALL. — As described for the species. A seed-like, egg-shaped, or more compressed, elongate cell in the buds of Quercus alba.

RANGE. — Undoubtedly as indicated for the agamic form erinacei (fig. 68) ; in the northeastern quarter of the United States and southern Canada, from Maine and Minnesota to Maryland and central Missouri. Known definitely from: New York: Ithaca (acc. Triggerson 1914). D.C.: Washington (acc. Weld 1926). Ohio: Cincinnati (acc. Wieman 1915) . Indiana: Miller (acc. Weld 1926). Charlestown and Memphis (E. W. Spieth in Kinsey coll.). Clinton (Kinsey coll.). Illinois: Ravinia (types, Weld coll, in Mus. Comp. Zook). Glencoe, Winnetka, and Willow Springs (acc. Weld 1926). Kentucky: Paducah (variety? Kinsey coll.).

While bicolens is unknown except from Triggerson’s and Wieman’s studies, Weld’s material, and my southern Indiana and Kentucky series, the insect is of course to be expected wherever the galls of the agamic generation occur in abun- dance. The galls of bicolens are not usually visible until after the buds have opened and, as Weld (1926), suggests, “The easiest way to rear the flies is to locate a tree in the fall well infested with the hedge hog gall and from this tree gather twigs in the spring just before the buds start, putting them in a bottle of water and setting the whole in a battery jar with a cloth over the top.” This bisexual insect is very close to gemmula , the bisexual form of prinoides; and the bisexual forms to be discovered for for the other eastern species and varieties of Acraspis will probably need careful comparisons in making determinations. Altho the agamic females have oviposited late in the fall or early winter, it is not until nearly six months later, after the middle of April, that the eggs hatch. Adults were mature and emerging from my southern Indiana material on April 22 and May 1, 8, and 9 (1927). Wieman (1915) secured adults at Cincinnati over a period of two weeks beginning April 23, 1914. Weld (1926) reports pupae near Chicago on April 28 (1913), and adults on May 1-20 (in 1913), on May 6 (1924 at Washington) , and May 17 (1909 near Chicago) . Triggerson, who first recognized on the basis of both laboratory and field observations, that this represents the bisexual generation of erinacei , did not find the eggs hatching to produce these bi- sexual insects at Ithaca, New York, until after May 8. Quot- ing from Triggerson : “On the twelfth of May a slight swelling, at the apex of which an empty egg shell was visible, appeared on the lower green portion of the scale . . . This proved to be a freshly formed gall, containing a young larva of Dryophanta erinacei. The gall at this stage was thin-walled, with a pebbled surface, greenish in color, and contained a watery fluid. The egg-shell remains attached to the apex of the gall until the latter has reached considerable size, when it dries up and disappears. These hypertrophies develop rapidly, as many as three ap- pearing on one scale. The wall of the gall has by this time changed to a yellowish brown color, and soon becomes quite dry and brittle. “Galls also develop on the apical portion of the leaf and flower buds . . . The terminal galls are of the same size as those on the scales, varying in number from one to four, and when mature are reddish brown . . . males and females similar in size and character emerge from the two galls. . . . The difference in color in the galls is due to the normal dif- ference of the tissue of which they are formed. “Shoots were brought into the laboratory, placed in water and covered with bell jars. Here about noon on the twenty- first of May the first male and female emerged. They were quite vigorous, and about four-thirty in the afternoon the fe- male was noticed actively moving along the midrib of the young leaf. Suddenly she stopped, and set up a rapid nodding motion which lasted thirty-five seconds, during which the ovi- positor was thrust into the tissue. The insect remained mo- tionless for a time, then withdrew the ovipositor, filling the passage with a yellow substance which, as in the agamic form, is probably a secretion poured forth by the accessory glands of the reproductive system. The process was repeated four times in succession without moving the body forward. Each time the ovipositor was inserted the body was curved slightly more than at the preceding puncture. The entire time oc- cupied by the four ovipositions was from four-thirty-four to four-fifty, or sixteen minutes, thus allowing four minutes to each oviposition of which a little over two minutes and a half was occupied by the passage of the egg. Many other observa- tions were made, and the time in all instances corresponded to the first recorded. “While the first observations of oviposition were made with- out having seen copulation occur, in all the following instances it was observed. The male strikes the female several times with the antennae after which the latter rests quiet. The male then clasps her thorax latero-caudad of the second pair of wings with the second pair of legs, while the first pair rest on the dorso cephalic portion of the thorax, and the third pair extend slightly latero-cephalad of the abdomen; copulation takes place, lasting for a few minutes. “The egg of the sexual form ... is oval, 160^. x450^. provided with a pedicel 750 in length, which is shorter than in the agamic form. It is always placed in the fibro-vas- cular bundles, and at an angle of about 80° to the axis of the leaf. The egg differs from that of the agamic form only in the elongate portion being shorter. “The larva is characteristic of the Cynipidae, having a slightly depressed head, fine needle-like mandibles, broad thorax, and reflexed pointed abdomen. During development the abdomen does not become as enlarged as in the agamic form. The thorax also continues prominent throughout all larval stages, which is not the case with the agamic form. . . . “In the open the adults did not emerge until the twenty-ninth of May, and continued to oviposit from that time until the fifth of June. Oviposition here was as observed in the labora- tory, the time occupied corresponding exactly to that already noted.” In this 1914 paper, Triggerson includes a small photograph of the female of this form, figures the young galls in the bud scales, details the mouth parts, wings, and antennae — the lat- ter showing sensory pits similar to those of the agamic female — and figures the egg of this insect. He also shows a longi- tudinal section thru a larva including a portion of the Mal- pighian tubule. Wieman (1915) has studied the spermatogenesis of the male of the bisexual erinacei. He admits his conclusions as some- what uncertain and perhaps open to question because of diffi- culty in seriation of his sections, and more especially fragmen- tary because the maturation stages of the eggs of this genera- tion and of the agamic female were not studied. In the male he found “but one true maturation division, namely that of the second spermatocyte. The first spermatocyte division is indi- cated by the pinching off of a small quantity of chromatin- free cytoplasm which forms the so-called polar body.” In the second division “it would seem that each chromosome is di- vided quantitatively by a longitudinal splitting; although it must be remembered that attempts at verifying this conclu- sion by studying the constituents of the daughter groups [were] not satisfactory owing to the tangled condition of the chromosomes.” Counts in the metaphase seemed to show 12 chromosomes as, presumably, the haploid number. Counts of somatic tissues of the male, although not conclusive, also seemed to give 12 as the normal number. Counts of female somatic tissues seemed near this same number, the best prep- arations, coming from follicle cells of the ovary, giving counts of 13, 14, and 13, respectively. Wieman’s findings are unexpected, for among many Hy- men optera the males are haploid because they are produced parthenogenetically from eggs in which reduction has oc- curred, but the females are diploid because, if they are pro- duced parthenogenetically, they come from eggs in which re- duction has not occurred. Doncaster’s work (1910-1916) seems to confirm this general statement for the cynipid species Neuroterus baccarum, and Patterson (1928) accepts this as the explanation of the demonstrated fact that agamic Cyn- ipidae are apparently of two sorts : those that produce females only (because no reduction occurs), and those that produce males only (because reduction does occur). If Wieman’s re- sults are acceptable, they suggest that the bisexual female is haploid as well as the male, for even if the accuracy of the somatic count on erinacei is open to question, the count falls short of the expected 2X number of 24 chromosomes. Wieman suggests that the slight difference between the male and female counts in this species is due to the presence of true sex chromosomes in the female. Either Doncaster or Wieman is wrong in the cytologic findings, or, if both are correct, there is more than one type of maturation involved with the alternation of generations of diverse species of Cynipidae. It is highly desirable that Wieman’s brief investigations be ex- tended by further work on erinacei.