The Social Wasps (Hymenoptera: Vespidae) of Indiana

An updated taxonomic treatment of the social wasps (Hymenoptera: Vespidae) of Indiana is made. Illustrated identification keys are provided for species of Polistes, Vespa, Vespu/a, and Dolichovespula. New distributional records and biological notes are provided for each species, Eusocial wasps, including paper wasps, hornets, and yeilowjackets, occur in colonies associated with elaborate paper nests and show: (1) eooperative brood care; (2) reproductive division of labor; and (3) an overlap of generations (Wilson, 1971). The eusocial wasps of Indiana were last treated taxonomically by Chandler (1965). The present paper, which updates Chandler's work, presents current taxonomy, identification keys, new distributional and biological data, and selected recent references. Introduction to the Family Vespidae. Chandler (1965) included in the family Vespidae two subfamilies with eusocial species, Polistinae and Vespinae, together with solitary species in the subfamilies Eumeninae and Zethinae; subsequent taxonomic treatment of these groups has changed. The most recent catalog of Hymenoptera (Krombein 1979) restricted the family Vespidae to eusocial species in the subfamilies Polistinae and Vespinae. However, a recent phylogenetic analysis of the world social wasps and their relatives (Carpenter 1982) has led to a new classification of the family Vespidae in which the subfamilies Polistinae and Vespinae are united with four other subfamilies that inelude mostly solitary species. Temperate eusocial wasp colonies are normally annual, being initiated in spring, reaching their peak in mid to late summer, and declining by late summer to fall. The paper nest, used only during the year in which it is constructed, consists of masticated wood fibers mixed with salivary secretions; nest architecture varies among species and may be of systematic importance. Larvae are fed a meat diet consisting primarily of pieces of arthropod prey captured by worker wasps. Adults imbibe a variety of liquid carbohy­ drates, larval secretions, and fluids from captured prey. The sting of female eusocial wasps appears never to be used in prey capture (as it is in solitary wasps); instead, prey capture is accomplished by grasping with the legs and use of powerful mandibles. This paper is not intended to cover the importance of social wasps, a topic reviewed by Akre et al. (1981) and Akre and MacDonald (1986). However, a couple of items will be mentioned briefly. Foraging vespids almost never sting unless captured and mishandled; almost all stinging episodes are associated with purposeful or inadvertent disturbance of the nest. Secondly, all social wasp stings are very painful, potentially dangerous if I Journal paper number 11,227, Purdue Agricultural Experiment Station, W. Lafayette, Indiana. Work supported in part by Purdue Agricultural Experiment Station project number 58045. 2Department of Entomology, Purdue University, W, Lafayette, Indiana, 47907, 3 Archbold Biological Station, P.O. Box 2057, Lake Placid, florida 33852 1 MacDonald and Deyrup: The Social Wasps (Hymenoptera: Vespidae) of Indiana Published by ValpoScholar, 1989 156 THE GREAT LAKES ENTOMOLOGIST Vol. 22, No.3 delivered in the neck region where rapid swelling can block breathing passages, and may induce dangerous systemic reactions in hypersensitive individuals. Recent research suggests that reactions to social wasp and social bee venoms appear to be at least group specific; for example, people allergic to honey bee venom are not necessarily allergic to social wasp venom. Accordingly, accurate identification of stinging Hymenoptera, including all social wasps, is very important and may even provide the basis for successful diagnosis and eventual desensitization with pure venom extracts obtained from the offending species. Lastly, destruction of mOst social wasp colonies can be difficult and potentially dangerous, and is best left to experienced people with the proper protective gear and effective insecticidal products. Identification of the Social Vespidae. The intent of this paper is to facilitate identification of Indiana social wasps without resorting to characters that require special preparation of specimens, such as dissecting and clearing of male genitalia. Structural characters are used whenever possible, but most species can be separated only through variations in color patterns. Nearly all specimens of Vespinae may be detennined by the maculation patterns of the gaster, but some Polistes species are not easily identified by coloration. Collection of a series of adults and the nest itself is strongly recommended to facilitate identification of Polistes species. Although prepared for Indiana, the information and keys cover the social wasp fauna existing in surrounding states as well. The key to Polistes, however, wa~ developed to handle Indiana specimens and may not suffice to accurately identify all specimens from neighboring states. Social wasp researchers employ a number of morphological terms in identification keys that may not be found in general references. Common terms adopted for use in this paper are listed below and the structures are illustrated in Figure I and in figures cited in the keys: Carina: a slightly raised ridge on the integument (referred to as the "keel" in some Polistes keys). Corona: a more or less rectangular yellow area just above and between the ante! Ulal bases. Gaster: the main portion of the abdomen posterior to the pedicel. Genal band: a narrow area immediately posterior to each compound eye. Jugal lobe: the basal, posterior lobe of the hind wing of Polistes (often referred to as the anal lobe). Maculation: a pattern of colors; in Vespula, the pattern of yellow or white against a black background on the gaster or clypeus. Ocular sinus: a small yellow area lying within the medial identation of each compound eye. Oculomalar space: a narrow area immediately beneath each compound eye and just above each mandible base. Pedicel: the "waist" between the gaster and the propodeum; also, the second ante! Ulal segment. Propodeum: the posterior plate of the thorax continuous with the pedicel (actually, the propodeum is the first true abdominal segment united with the last thoracic seg­ ment). Key to the Subfamilies of Eusocial Vespidae 1. Gastral tergum I narrowed anteriorly and convex in lateral view (fig. 2): c1ypeus rounded or narrowly truncate ventrally (fig. 4); hindwing with a jugal lobe: slender wasps; nest a single, exposed comb . Polistinae l' . Gastral tergum I strongly truncate anteriorly and arising nearly vertically from the pedicel in lateral view (fig. 3); clypeus broadly truncate and concave ventrally (fig. 5); hindwing lacking a jugal lobe; robust wasps; nest consists of multiple combs enclosed in a paper envelope . Vespinae 2 The Great Lakes Entomologist, Vol. 22, No. 3 [1989], Art. 7 http://scholar.valpo. edu/tgle/vol22/iss3/7 1989 THE GREAT LAKES ENTOMOLOGIST 157