Copyrighted 1910, by THE COLUMBIA UNIVERSITY PRESS PRESS OF THE NEW ERA PRINTING COMPANY TO MY WIFE DORA BAY EMERSON "The Subject indeed is small, but not inglorious. The Ant, as the Prince of Wisdom is pleased to inform us, is exceeding wise. In this Light it may, without Vanity, boast of its being related to you, and therefore by right of Kindred merits your Protection." -WILLIAM GOULD, "An Account of English Ants," 1747. PREFACE. This volume had its inception in a series of eight lectures delivered at Columbia University during the spring of 1905, and represents, in a much condensed form, the results of a decade of uninterrupted study of the Formicidæ, and of the works that have been written on these insects. If an excuse were required for its publication, one might be found in the fact that for many years no comprehensive treatise on the ants has appeared in the English language. This may be regarded as a reproach to English and American zoölogists, since during all this time almost the only active contributors to myrmecology were to be found on the European continent. It must be admitted, however, that the methods of publication adopted by continental writers have not been such as to attract the attention of English-speaking students, since their works have not only been issued in a variety of languages-French, German, Swedish, Italian, Russian, etc.-but also in a great number of often very obscure, local or inaccessible journals and proceedings of learned societies. Moreover, most of the continental observers within recent years have been too busy with special lines of investigation to publish compendia on myrmecology. It thus happens that although ants are our most abundant and most conspicuously active insects, they have not, till very recently, received any serious attention from American systematists, and the descriptions of most of our species must still be sought in a lot of more or less fragmentary foreign contributions. My work began in an endeavor to increase our systematic knowledge of the North American ants, but I was fascinated by the activities of these insects and soon saw the advantage of studying their taxonomy and ethology conjointly. This method, which was, indeed, unavoidable, has greatly retarded the appearance of the present work, for it was impossible to write about the behavior of many of our most interesting forms till their taxonomic status had been definitely settled. On the other hand, I could find no satisfaction in devoting all my energies to collecting and labelling specimens without stopping to observe the many surprising ethological facts that were at the same time thrusting themselves upon my attention. My observations have now covered so much of our fauna that I shall soon be able to publish a systematic monograph, which will, I hope, enable the student to form a rapid acquaintance with our ants, without recourse to the scattered and often very meager descriptions that have hitherto served as the taxonomy of the North American species. I frankly admit that in writing the following pages I have endeavored to appeal to several classes of readers-to the general reader, who is always more or less interested in ants; to the zoologist, who cannot afford to ignore their polymorphism or their symbiotic and parasitic relationships; to the entomologist, who should study the ants if only for the purpose of modifying his views on the limits of genera and species, and to the comparative psychologist, who is sure to find in them the most intricate instincts and the closest approach to intelligence among invertebrate animals. Of course, the desire to interest so many must result in a work containing much that will be dull or incomprehensible to any one class of readers; thus the technical terms and descriptions, which are full of significance to the entomologist, are merely so much dead verbiage to the general reader, and the laboratory zoologist, who shrinks at the mention of psychological matters, will care little about ant behavior beyond its physiological implications. With the exception of the appendices and the first chapter, which serves as an introduction, my account of the ants falls naturally into two parts: a first, which is largely morphological, and comprises Chapters II to X; and a second, devoted to ethological considerations and embracing the remaining chapters. To some it may seem that too much space has been devoted to the relations of ants to other organisms and to other ants (Chapters XVI-XXVII), but I justify my procedure on the ground that this subject is the one in which I have been most interested, the one in which most advancement has been made within recent years, and the one that has been fraught with the greatest differences. of interpretation. The series of appendices has been added largely as an aid to the beginner in the study of myrmecology. The tables for the identification of our North American ants are very incomplete, but could not have been extended to embrace the species, subspecies and varieties, and the different castes, as well as the genera, without unduly increasing the size of the book. I hope to make good this defect in the monograph to which I have alluded. In the meantime, I shall be glad to identify ants for anyone who is interested in their study, especially if the specimens are collected in America north of Mexico. The identification of such material serves a double purpose: that of increasing our knowledge of the geographical distribution of our species, and of spreading throughout the country collections of correctly identified |