Imágenes de páginas
PDF
EPUB

1878, while very important, include only one work which describes new North American species-Vol. I of the Diptera in Biologia Centrali-Americana.

In 1879 appeared the first paper of S. W. Williston, inaugurating a new American period, which has continued to the present time. After a few years D. W. Coquillet began to publish, followed by C. H. Tyler Townsend, and he by others, until the number of those who publish occasional papers is now ten or more.

The recent appearance of Dr. Williston's Manual of North American Diptera gives reason to hope that the immediate future will greatly increase the number of workers in this order, so that we will be justified in counting a new era from 1896. It is now possible to determine the genera of nearly all the flies of North America, including the West Indies, with no other work of reference than this volume. More than Cresson's Synopsis does for the Hymenoptera, or Leconte and Harris' volume does for the Coleoptera, this book does for the Diptera, because it includes the territory southward to the Isthmus of Panama. Only the Tachinidæ and Dexiidæ are not tabulated and analytically reduced to genera, and in this confused mass a bibliographical generic list is given, extending to 272 numbers.

While the book purports to be a second edition of the small one published by the same author in 1888, it is practically a new work, having been entirely rewritten, greatly enlarged, and extended to include the entire order with the exception noted. The bibliography since 1878 is given, and all genera not found in Osten Sacken's catalogue have references (in the index) to their descriptions.

The external anatomy of Diptera is very fully treated. Dr. J. B. Smith's interpretation of the mouth parts is given in addition to the usual one, the author not assuming to decide between them. Professor J. H. Comstock's system of wing nomenclature, as used in his manual, is given a place for comparison, but is not used in the work "for two reasons: First, that it has not yet been fully crystallized into permanent shape; second, because nearly all the existing literature has the nomenclature here employed, and to use a new one would largely defeat the object of the work in the hands of the beginner." Baron Osten Sacken's system of bristle-naming or chatotaxy is quite fully set forth. Each family table is preceded by a full exposition of the family characters and a description of the larva, its mode of life, food, etc. (where known).

2 Manual of North American Diptera. By Samuel W. Williston, M. D., Ph. D. Pp. LIV, 167. James T. Hathaway, New Haven, Conn., 297 Crown St. Paper, $2.00; cloth, $2.25.

The family known heretofore as Blepharoceride appears as Liponeuridæ. This change of name was made by Osten Sacken several years ago. He has more recently abandoned the change in a published paper, and there seems no reason why the old name should be displaced.

The families Xylophagidae and Conomyidae are united with Leptide, thus simplifying the family and generic diagnoses. This seems a rather surprising arrangement, yet may be logically defended.

The family Lonchæide is united with the Sapromyzida. Aside from these changes there are no important differences in the higher categories between the last catalogue and the present work.

While the printing and binding are excellent, there are a number of typographical errors especially in the spelling of generic names, as for instance in Subulomyia, p. 43, the list of lepidopterous genera on p. 146 (five mistakes) and the list of Tachinid and Dexiid genera, p. 147 (four mistakes). But few of these, however, are more than the interchanging or omission of a letter.

This book is Dr. Williston's most important single contribution to dipterology thus far, and it worthily exhibits the industry, experience and ability of the author, which have secured for him world-wide recognition as a dipterist of the highest rank.-J. M. ALDRICH, Moscow, Idaho.

Color Variation of a Beetle.-Mr. W. Baterson gives an account of his statistical examination of the color variations of the beetle Gonioctena variabilis, which appears to be abundant in hilly places in the south of Spain. He finds that we have here to do with a species whose members exhibit variation in several different respects, and that the variations occur in such a way that the individuals must be conceived as grouped round several special typical forms. There is thus not one normal for the species but several, though all live in the same localities under the same conditions, and though they breed freely all together these various forms are commoner than the intermediates between them. Some time since, when calling attention to the excessive variability of the color of Coccinella decempunctata and the no less striking constancy of C. septempunctata which lives with it, Mr. Bateson remarked that to ask us to believe that the color of the one is constant, because it matters to the animal, and that the other is variable because it does not matter, is to ask us to abrogate reason. Mr. Wallace, it seems, is of this very opinion; but he does not explain how it is that the color of one is so important, and the color of the other unimportant to the beetle. (Journal Royal Microscopical Society.)

American Nematinæ.-The third of the technical series of bulletins from the U. S. Division of Entomology is entitled "Revision of the Nemating of North America, a Subfamily of Leaf-feeding Hymenoptera of the Family Tenthredinidæ." It is by Mr. C. L. Marlatt, and extends over 135 pages, with one excellent plate and several illustrations in the text. We quote from the introduction as follows:

"The subfamily Nematina of Thompson or Nematina of Cameron (Konow's subtribe Nematides) comprises a very large group of closely allied species, distributed in the classification adopted by the author among nearly a score of genera. They range from very small insects to medium sized, but include no very large species, or in length from 2 to 12 mm. They are for the most part smooth, shining, and rather soft bodied, and are variously colored, but yet presenting frequently a confusing similarity in general form, and particularly in coloration, rendering their generic and specific references in some cases difficult. In point of number of species and abundance of individuals this subfamily far exceeds any other of the corresponding groups in the family Tenthredinidæ, and in variation and peculiarities in larval habits and in economic importance many of the species belonging to it have a very great interest.

"Geographical Distribution.-The Nematinæ are distinctly northern in their range, reaching their greatest development in abundance of species and specimens in the transition and boreal zones, and extend northward into the circumpolar regions-species occurring abundantly in Greenland, Iceland, and Spitzbergen. Southward they become less and less numerous, and are particularly wanting in tropical countries. - This is illustrated very forcibly in Europe by the occurrence of over 70 species of the old genus Nematus in Scotland (Cameron) and 95 in Sweden (Thompson) as against 12 about Naples, Italy (Costa); and the same discrepancy exists between the temperate and subarctic region of America and the Southern States and Mexico.

"Food-plants.-Their food-plants cover a wide range, some species affecting grasses, one or two very destructive to the grains, others various deciduous trees and shrubs, and still others conifers. The majority of the species occur, however, on plants of the families Salicaceæ, Betulaceæ, Rosacea, and Coniferæ, in the order given.

“Life history and habits.-The Nematines are among the first sawflies to appear in spring, occurring abundantly on trees on the first appearance of the leaves. They do not often frequent flowers, except, at least, those of the plants upon which their larvæ feed. Many willow species, for example, occur abundantly on the earliest spring bloom of the

willow. In common with other sawflies, however, they rarely leave their larval food-plants, and to be collected successfully a knowledge of their habits in this respect is very desirable.

"In number of broods great diversity is found, and the normal rule of most Tenthredinidæ, of a single yearly brood, is frequently deviated from. Some species are known to be limited in number of broods only by the length of the season, as, for example, Pteronus ventralis Say, the common willow species. Two annual generations are common, but many species are single brooded, the larvæ entering the soil or other material or remaining in their galls at the completion of growth and continuing in dormant condition until the following spring, when shortly before they emerge as perfect insects the change to the pupal condition takes place. The males normally appear a few days before the females, and the duration of the life of the adults of both sexes is short, not often exceeding a week or ten days. Of a large percentage of the species no males are known, and in the case of many species careful and repeated breeding records indicate that males are very rarely produced.

"In some species parthenogenesis is complete; that is, the eggs from unimpregnated females produce other females. In other instances of parthenogenesis, however, either males only are developed from unfertilized ova or females very rarely.

"The union of the sexes takes place very shortly after the appearance of the females, and egg deposition closely follows. The eggs are inserted either singly or a number together in the young twigs, larger veins, petioles, in the surface parenchyma, or in the edges of the leaves, the single exception being the case of the gooseberry sawfly (Pteronus ribesii), which merely glues its eggs to the leaf without making any incision whatever.

"Most of the species are external feeders on the foliage of plants, but the species of two genera, Euura and Pontania, so far as their habits. have been studied, are gall makers, and pass their early life in the interior of the plants, either in the stems without causing abnormal growths or in the excrescences or galls on the stems and leaves. At least one American species develops in the rolled or folded edges of the leaf. The larvæ are 20-footed, some solitary, others gregarious—the latter usually more brightly colored and possessing means of protection in glands secreting a noxious fluid. Most of the solitary ones are green and not readily observed. They usually feed from the underside of the leaves, eating from the edge or cutting circular holes in the general surface, and in some cases taking everything but the stronger veins. Many species rest quietly during the day, feeding only at night.

Some have the habit of throwing the posterior segments violently upward to frighten away parasites or enemies; others adhere to the leaves or twigs by the thoracic feet only, coiling the posterior segments under the middle ones."

Entomological Notes.-Prof. F. L. Harvey monographs in an elaborate manner the Currant Fly, Epochra canadensis, in the report of the Maine Experiment Station.

The North American species of Nemobius are monographed by Mr. S. H. Scudder (Journ. N. Y. Ent. Soc., Sept., 1896). Several new species are described.

Mr. Alex. D. MacGillivray has recently monographed the American species of Isotoma in the Canadian Entomologist

In the check-list of the Coccida published by Prof. T. D. A. Cockerell, in the Bulletin of the Illinois State Laboratory of Natural History (vol. IV, pp. 318-339) 773 species are listed.

A number of new species of Scarabeidæ are described by Martin L. Linell in the Proceedings U. S. National Museum (vol. XVIII, pp. 721-731.

Prof. J. B. Smith discusses again the San José Scale (Aspidiotus perniciosus) in Bulletin 116 of the New Jersey Station.

"The Principal Household Insects of the United Stated" is the title of the extremely valuable and interesting Bulletin No. 4 of the Division of Entomology, U. S. Dept. of Agriculture. It was prepared by Messrs. Howard, Marlatt and Chittenden.

The Lamiina of North America are monographed by Messrs. C. W. Leng and John Hamilton, in the Transactions of the American Entomological Society (vol. XXIII, No. 2). In the same issue Mr. William H. Ashmead describes a large number of new parasitic Hymenoptera. Mr. F. M. Webster discusses the Chench Bug in Bulletin 69 of the Ohio Experiment Station, and several destructive insects in Bulletin 68.

The Phylogeny of the Hymenoptera has recently been discussed by Mr. Ashmead in an interesting and authoritative paper in the Proceedings of the Entomological Society of Washington (vol. III, No. 5).

« AnteriorContinuar »