TERRITORIAL BEHAVIOR IN THE CICADA KILLER WASP, SPHECIUS SPECIOSUS (DRURY) (Hymenoptera: Sphecidae). I by NORMAN LIN 1) (255 E. 7 St., Brookly 18, N. Y.) (With 6 Figures) , (Ree. 15-VIII-Ig6I) INTRODUCTION Territoriality among invertebrates, though virtually unexplored, is known in one form or another in the Crustacea and Insecta. In the latter it is found in Coleoptera (PuKOwsKr, 1933), Hymenoptera (MINKIE??'ICZ, 1934), Odonata (JACOBS, 1955), and Orthoptera (ALEXANDER, in press). The cicada killer, Sphecius speciosus (Drury), is a large ground-nesting wasp which occurs in colonies numbering up to several hundred burrows. There is an average of 15.8 cells per nest, each of which is provisioned with 1-3 cicadas (DAMBACH and GOOD, 1943). Territoriality in the cicada killer was first suspected by DAMBACH and GooD, although DAVIS (1920) had described aspects of it erroneously as mating behavior. The present study was conducted on the Parade Grounds, a 40-acre athletic field in Brooklyn, New York. Initial observations on the cicada killer were made during the summers of 1956 and 1957; more intensive study was carried out in 1958, 1959, and 1960. The bulk of the data was obtained from four colonies, located on sandy tracts used as footpaths, running along the sides of two baseball fields. A wire fence partitioned by vertical bars nine feet apart ran the length of the tracts. Each nine foot spacing of fence along the tracts was numbered and referred to as a section (Fig. I). The cicada killer emergence holes and territories were mapped by section. Most observations were made on the footpaths; a few were made in the surrounding areas. In 1960, observations were aided by marking wasps with enamel paint on portions of the abdomen and wings. Territory owners could be observed at extremely close quarters without interrupting their activity. 1) I am indebted to Dr RICHARDD. ALEXANDERof the University of Michigan who read the manuscript at various stages and gave constructive criticism. 116 THE NATURE OF TERRITORIALITY IN CICADA-KILLER WASPS A territory is defined here as "any defended area" by NOBLE (1939) and NICE (1941). The territories of male cicada killers were located along the colonial tracts and consisted of strips of ground ranging from about 16 feet in length and 6 feet in width to about 4 feet in length and 4 feet in width. These areas were vigorously defended by cicada killer males against intrusion by other males, other species of insects, birds, and even thrown or rolled pebbles. The wasps flew, hovered, or perched within their territories. They left frequently, usually to chase intruders, and then returned generally within a matter of seconds. "Spontaneous" flights from the territory, in which there was no apparent external flight stimulus, also occurred. When the wasps returned to the territory they usually perched on or next to some small selected object, here referred to as the territorial perch. The territorial perch was usually an emergence hole; for example, in one colony in 1958, 52 of 56 located territorial perches were emergence holes (Fig. 2). The four remaining perches were: a piece of brightly colored glass, the bright brass button of a muslin bag, and (twice) parts of a black hand rail. The waspsSimilar localizedaggressive less anddefinitely perching onbehavior the handrail has beenthan reportedon the otherfor some perches. sphe- cids of the genus Astata. These species may differ from the cicada killer in two respects: they apparently do not perch on or next to emergence holes (SHUCKARD, 1837, MINKIEw'ICZ, 1934, WILLIAMS, 1946, EVANS, 1957) ; and EVANS reports that in A. unicolor the perching males show no obvious res- ponse to each other, nor can flights "... be elicited regularly by tossing pebbles over the perches, as can the precopulatory flights of certain other digger wasps". MINKIEwICZ, however, found that if one male of A. winor approached another's perch they rolled together, "dans un corps-a-corps formidable", and WILLIAMS states that males of A. inunigrans pursue pass- ing insects and then return to or near their station. A male cicada killer rests more frequently next to the emergency hole perch than over it. Perching over the emergence hole is usually done with the abdo- men resting across the hole or extending partway into it. No males were ever seen to enter the emergence holes they used as territorial perches, but from 1956 to 1958, eight cicada killers of undetermined sex were found within completed emergence holes. One of them emerged from a hole known to have been formed a day earlier. This wasp had apparently entered the hole from the outside, since each wasp digs its own emergence hole in freeing itself from its isolated cell within the nest. One male wasp re-opened a partly closed hole in muddy ground by climbing up and down within it while .