Vol. 91, No. 2, March & April, 1986 69 NESTING BIOLOGY OF ECTEMNIUS BASIFLAVUS IN TRINIDAD (HYMENOPTERA: SPHECIDAE) 1 E. McC. Callan 2 ABSTRACT: The nest and prey of Ectemnius basiflavus are reported from Trinidad, West Indies. The nest, from which 6 males and 3 females were reared, was in the living stem of Hyptis sp. (Cruciferae) and was provisioned with Otitidae (Diptera). Crabronine wasps of the genus Ectemnius nest in diverse situations and commonly prey on adult Diptera. Ectemnius basiflavus (Brethes) ranges from Mexico to Argentina. Bohart and Menke (1976) gave synonymy. Schrottky (1914) described both sexes (as Xylocrabro umbrosus) from Paraguay, with brief comments by A.W. Bertoni on its biology. The following account augments Bertoni's notes. METHODS In Trinidad, West Indies I took a male of Ectemnius basiflavus on 24 January 1 945 at Preysal, 6 km east of Couva, on the flowers of Borreria verticillata (L.) Meyer (Rubiaceae), a small unobtrusive plant with compact white nectar-producing flowers, much frequented by bees and wasps. My observations were made on a nest found on 1 February 1949 in the living pithy stem of a common weed Hyptis sp. (Cruciferae) in my garden at St. Augustine, a residential area 13 km east of Port of Spain. RESULTS AND DISCUSSION The nest comprised a linear series of 9 cells within the stem of the plant separated by transverse partitions made of fine particles of pith. The partitions were about 1 mm wide and the cells 9 to 12 mm long. Each cell contained an elongated, cylindrical cocoon, rounded at both ends, and yellowish brown in color. The cocoon was made of fine silken threads, and was suspended by a few projecting filaments within the cell. The walls of the cocoon were thin, soft and delicate with almost the texture of tissue. At the lower end of each cocoon was the meconium, a dark mass of larval excrement, visible through the walls of the cocoon. Disposed around the Deceived June 28, 1985. Accepted November 29, 1985. 2 13 Gellibrand Street, Campbell, Canberra, A.C.T. 2601, Australia. ENT. NEWS 97(2): 69-70, March & April, 1986
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