Alfred Charles Kinsey

“ Because of the poor distinction of several of the genera of the oak gall makers, it seems unwise to employ the generic titles Cynips, Callirhytis, Philonix, etc., until a careful revision of the genera of the family has been made. For that reason, I have used the name Andricus, the most meaningless of all these titles, with a number of the forms.
To distinguish the alternate generations of a species, I have had to adopt a new form of naming. It is highly unreasonable to continue to use the names given independently to each generation before the connections of the two forms were understood. ”

“ We then become impressed with the truth of the assertion that no two individuals are exactly alike. And if we extend our investigations to several dozen individuals, we shall be confused by the varying characters that enter into any population which ordinarily passes as a species.
But if, on the other hand, we extend our examination to several hundred such individuals, we shall become impressed with another opinion, namely that there are many more points of uniformity than of variation among individuals taken from a given locality and habitat. ”

“ The adults are all imperfect. Holotype female and paratype adults and galls in the collections of The American Museum of Natural History; paratype adults in the collection of the author; galls at Leland Stanford University and the U. S. National Museum. These galls develop early on the unfolding leaves, looking like small air-bubbles blown in the tissue. The galls were always very new and fresh when gathered, but were also practically mature. The development of this generation of the species must be a matter of only a month or two; the other generation is unknown. ”

“ It is thick woodland and we find only stray galls now and again. They are smooth and naked specimens, for aught we can tell like the smooth galls of erinacei. A mile down the road we find an open meadow where two isolated trees offer promise of richer collections. The farm boy helps, and we collect more smooth galls while we wonder about the varied mixture which spreads so many miles back of us. It is drizzling now, and sheets of fine snow come whirling off the mountain, but we espy a tree in the next open, and in the gathering dusk find—many naked but only two spiny galls for our collections! ”

“ Now, it is conspicuous that specialization in the choice of hosts is restricted to the species of particular tribes, and that practically every species in those tribes has adopted the special host. All but one of the species of the Cynipini are found regularly on oaks and all of the species of Rhoditini are found as regularly on roses, though rarely one or two of the species of each group will produce galls on a second plant as well as upon their own hosts. Finally, it is to be seen that all of the species which inhabit the plants of the many genera belong to the one tribe Aulacini. ”

“ Only experience with each species, involving continued observation of specimens of the galls, and obtaining of such information as may be supplied by the size of the gall, the degree of development shown by the insect within the gall, etc., can supply information of the approach of the emergence date for a particular species. Most of the solid, hard, woody, or dry-shelled galls may be kept successfully for many months, but the adults of soft, spongy, or hollow, succulent galls cannot be raised if the galls are gathered more than a week or even a few days before the insects are due to emerge. ”

“ Contemplating such close resemblance of species of different genera, we are wont to consider again how such "mimicry" may have arisen. Mimicry among inquilines in cynipid galls is of especial interest because of the absence of anything like a struggle for existence between the two organisms or an active struggle of these adults with any other organism. The inquiline usually reaches maturity and emerges from the gall, enjoying its first moment of a free or active life, some time after the brief adult life of the gall-wasp has been completed ”

“ One wonders to what extent this confusion as to the nature of species has delayed our understanding of the origin of species. Perhaps it is this confusion which leaves us without a convincing reply for the fundamentalists who insist that data from the evolution of domesticated plants and animals and from laboratory genetics may explain the origin of varieties but not of species. There is a peculiarly hollow ring to our statement that varieties are incipient species and that the evolution of species is too slow a process for human observation. ”

“ Every known species of the genus occurs on roses. One species, R. rosæ, is believed to produce a gall, rarely, on plants of the related genus Rubus but, although this gall does resemble the mossy gall occurring on rose, I do not know that any one has bred the adult wasps from the blackberry gall and definitely proved the identity of the maker. Other records of species of Rhodites occurring on Rubus are undoubtedly errors in the determination of the host. There is no question that the insects are remarkably specialized in their choice of hosts. ”

“ In another paper, on the phylogeny of the Cynipidæ, I am discussing this question in more detail and offering data which may be used to draw lines for natural genera. I hope to be able in the near future to revise the genera for the family. Until that time, it is surely wise not to maintain, in the description of new species, the several “genera” known as Cynips, Dryophanta, Callirhytis, Andricus, Biorhiza, Philonix, et al., species of which groups might all be described under the designation of "Andricus." ”

“ If the alternate generation of a species which is being studied is to lay its eggs in the flowers or acorns of the oak, recourse must be had to older trees growing in the open, such additional precautions then being taken as will insure as far as possible the immunity of the part of the tree used from attack by any other gall-wasps than those under observation. Some species will oviposit in the roots of trees. ”

“ In a single period, in a limited area, there must have existed a population from which all of the present-day species, with their varying grades of relationships, have developed. This history of the expansion of a single genetic stock into 93 distinct populations, by processes of mutation, isolation, and on occasion subsequent recombination into hybrid populations, is the story we have been unfolding in this study, and which we are now ready to fit into the geologic time and the geographic areas in which speciation probably proceeded in the genus. ”

“ It is hard to understand how this extreme specialization has come about. That the oak has advantages as a shelter for an insect is readily seen, but it belongs to a comparatively small family of plants, the genus has only a limited distribution over the world today, and, whatever the qualifications of the oaks, it is not apparent why other plants should be so completely abandoned. That these other plants are capable enough of producing galls is evident, for other gall insects of other families produce galls upon them in abundance. ”

“ Adler, in working out the life histories of European cynipids, employed only smaller coverings for the trees, but by the use of nets large enough to cover the entire tree it is possible to give a much wider range of activity to the insect; and by placing the breeding jars directly into the nets the danger of injuring these delicate insects by handling is entirely avoided.
The adults of most species of cynipids have very little vitality, and to effect oviposition they must usually reach the part of the plant in which the egg will be laid within a few hours after emerging from the gall. ”

“ It is this problem, the attainment of homogeneity out of a hybrid population, that has become the immigration problem of the American people in the last half-century. Whether homogeneity is a biologic virtue or not, the statesmen have shown themselves good taxonomists in their insistence that we cannot become a true species until barriers are erected to protect us from continued contributions of parental stock. Whether in peoples or insects, the melting pot cannot blend diverse materials that pour in too rapidly. ”

“ This belief may be due to our inadequate knowledge of biological phenomena, but it is significant that the agamic species of cynipids (e. g., Rhodites, Disholcaspis, and the genera with an alternation of generations) more often fail to reach maturity than do species of the bisexual groups (Aulacidea, Diastrophus, etc.) . It is a common experience to obtain only a score of adults from hundreds of the oak- or rose-galls, while many hundreds of adults may be secured easily from a score of galls of Aulacidea, for instance. ”

“ 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. ”

“ To morphology, physiology, and psychology we make certain assignments not only because we wish to deal with particular aspects of the organic organization, but because these sciences are adapted for dealing with ordinarily few species which may be taken to stand as types of whole orders and classes or phyla of plants or animals. For this reason these sciences contribute data on such problems as the relationships of the larger groups, their appearance in the geologic record, and their value as evidence of the processes of evolution itself. ”