Tachytes chrysopyga (Spinola 1842)

Tachytes chrysopyga (Spinola)

Lyrops chrysopyga Spinola, 1841, p. 112 (Cayenne).

Tachytes argentipes Smith, 1856, p. 306 (St. Vincent).—Ashmead, 1900, p. 227 (St. Vincent, Grenada).—Wolcott, 1923, p. 44 (Puerto Rico).

Tachytes insularis Cresson, 1865, p. 140 (Cuba).

This species is evidently widely distributed in subtropical and tropical America north of the equator. Identification of this species as Spinola’s L. chrysopyga is by A. S. Menke, who is preparing a catalog and reclassification of the Sphecidae (with R. M. Bohart). I have seen specimens from the following islands in the West Indies: Cuba, Hispaniola, Puerto Rico, St. Croix, St. John, Dominica, St. Vincent, and Grenada. On Dominica I have found it principally in cultivated land near the coast. Notes on its nesting behavior are presented below.

Following are the records from Dominica: 1 ♀, South Chiltern, 1600 feet, 19 February (Evans); 3 ♀ ♀, 1 ♂, mouth of Layou River, 6 February, 13 March (Evans); 69 ♀ ♀, 17 ♂ ♂, Clarke Hall, January–June, October–November (Wirth, Flint, Spangler, Steyskal, Gagne, Evans); 2 ♀ ♀, Melville Hall, February, March (Gagne, Evans); 1 ♀, Castle Bruce, March (Bray); 1 ♀, Cabrit Swamp, November (Spangler); 1 ♀, Colihaut, October (Spangler): 1 ♂, Grande Savane, February (Wirth): 1 ♂, Mero, January (Clarke).

BIOLOGY.—From 28 February to 11 March 1965, I made intermittent observations on a nesting aggregation of this wasp in a banana plantation, a few meters from the banks of the Layou River, near Clarke Hall. There were about 10 nests, all within 1.5 m2 between rows of banana trees, in partial shade. Nest entrances were in some cases only 15 cm apart; three were in the open, the remainder under leaves or dried grass, where they were difficult to locate unless the female was seen entering. Each nest entrance was surrounded by a rim of soil 5–7 cm across and about 1 cm high, the hole penetrating the center and fully 1 cm across at the entrance. The soil here was a soft, friable loam, somewhat sandier than in adjacent areas.

Females arrived in the nesting area carrying immature katydids on the wing, holding them by the antennae with their mandibles and also embracing them in flight with all three pairs of legs. Usually they plunged directly into the nest entrances, which were always left open, but occasionally prey-laden wasps would land on banana leaves before proceeding to the nest. On two occasions I had accidentally stepped on a nest, and returning females circled the area for several minutes before abandoning their prey; they evidently lacked the capacity to dig into the nest while keeping their prey.

Despite the large amount of active provisioning, I had little success in locating the cells, as the soil was filled with roots. I followed one burrow down 22 cm and another, 27 cm without locating any cells. In a third nest I found a cell containing a small larva at a depth of 18 cm. In each case the burrow passed straight down except for small curves around roots. The several prey taken from this cell, as well as several more taken from provisioning females, were all immature Tettigoniidae of the genera Turpilia and Neoconocephalus (det. A. B. Gurney). None of them appeared to have had the antennae amputated, as I found to be the case with Liris gryllicida.