PROC. ENTOMOL. SOC. WASH. 86(1), 1984, pp. 176-184 MATING AND NESTING BEHAVIOR OF TACHYTES INTERMEDIUS (VIERECK) (HYMENOPTERA: SPHECIDAE) Frank E. Kurczewski and Edmund J. Kurczewski (FEK) Department of Environmental and Forest Biology, S.U.N.Y. College of Environmental Science and Forestry, Syracuse, New York 13210; (EJK) 2921 Reed Street, Erie, Pennsylvania 16504. Abstract. — ThQ mating and nesting behavior of Tachytes intermedius (Viereck) were studied during 1980-1982 in a gravel pit in Erie County, Pennsylvania. Male activity and the copulatory positions of the male and female are described and compared with those of Tachysphex similis (Rohwer) and T. terminatus (Smith). Descriptions of the hunting components and the unearthment of the pygmy mole-cricket are given and are essentially identical to those of Tachytes mergus Fox. Details of prey transport and the unique method of entry into the open nest are presented. Prey stealing by conspecific females and worker Formica subsericea Say (Formicidae) was prevalent, but cleptoparasitism by satellite-flies (Sarco-phagidae) was absent. The 1-3-celled nests of T. intermedius extended deeper into sandy-gravelly soil than into clayey soil. The burrows entered the soil less vertically than those of other species of Tachytes, and the cells were often found at right angles to the burrow termini. Fully-provisioned cells of T. intermedius in July 1981 held 2-4 larger adult Neotridactylus apicialis (Say) (Tridactylidae), whereas such cells in August 1981 contained 4-6 smaller nymphs of this species. All prey were lightly paralyzed. The wasp's egg was placed between the fore-and midcoxae of the cricket in a position similar to that of other species of Larrinae that use orthopterous, non-mantid prey. One of the most unusual behavior patterns exhibited by the larrine wasps is that involving the unearthment, capture and provisionment of pygmy mole-crick-ets (Tridactylidae). In North America only two species of Tachytes, T. mergus Fox and T. intermedius (Viereck), are known to practice this behavior (Krombein, 1963; Krombein and Kurczewski, 1963; Kurczewski, 1966a; Kurczewski and Kurczewski, 1971; Williams, 1928). T. mergus is unique among the Nearctic Tachytes in its unusual manner of burrow construction and temporary nest closure. T. intermedius is a more "typical" Tachytes, based upon its digging behavior and lack of temporary closure. Despite the fact that some particulars for the nesting behavior of T. intermedius have been reported, the full spectrum of its ethology has yet to be presented. Krombein and Kurczewski (1963) noted a few females that were collected with tridactylid prey in Maryland, Florida and New York. Krombein (1963) observed females hunting Tridactylidae in mud along the Potomac River in Maryland. Kurczewski ( 1 966a) detailed the hunting, capture, transport, nest entry and species of prey of T. intermedius, but his presentation of the nest architecture, dimensions
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