Field Observations on the Habits of Aedes Taeniorhynchus

Abstract

The east or Atlantic coast of Florida is paralleled by a chain of narrow islands which are often referred to as the Beach. In the vicinity of Fort Pierce, the lagoon separating this offshore bar from the mainland is called Indian River (Fig. 1) . The outer or ocean beach is very straight and is backed by dunes behind which a number of plant associations parallel the coast. These increase in height as they succeed one another westward, from grass and weeds, through palmetto scrub, to the coastal hammock, a dense forest dominated by oaks and Sabal palms (for details, see Kurz 1942, and Davis 1943). The Indian River shore is a confusion of islands, peninsulas, coves, and sounds, more or less inundated by tide and covered with mangrove and salt marshes. These are the typical breeding areas for salt-marsh mosquitoes, and a considerable amount of control ditching was done here in the past. In the Fort Pierce region, both of Florida’s salt-marsh Aedes occur, but during the observation period under discussion, Aedes taeniorhynchus (Wiedeman) predominated while Aedes sollicitans (Walker) was present in negligible numbers only. We made our studies on the property of Mr. P. McConville, some six kilometers (4 mi.) north of Fort Pierce on the offshore bar. Most of the observations were made along a narrow winding road traversing this property from highway AlA near the outer beach to the Indian River shore (Fig. 1). This road crosses a number of the typical plant associations. In the first hundred meters from the highway, it cuts across palmetto scrub with Serenoa, CoccoZobis, Lantana, and other shrubs. It then curves WNW and passes through a hammock zone with a denser vegetation of oaks and palms. In this stretch the road ,crosses three old ditches which have become series of pools. Some of these pools hold water fairly continuously, but most of them, as well as the road tracks which bisect them, are flooded for short periods only after rains. These ditches are lined with mangrove and with Batis maritiuuut, Borrichia fru tescens, and Salicornia sp. Beyond the ditches, the vegetation along the road becomes more open, with many isolated shrubs separated by grass and such weeds as Chamecrista. Several kinds of vines mantle this vegetation. The road then turns SSW and in a number of short turns passes through an old orchard, mostly of mango and guava, with several rare imported trees and bushes. This orchard has grown wild for ten years and is now a dense scrub. The road ends at the Meadow (Fig. 2)) a triangular open area of about half an hectare (1 acre). It is mostly covered with a Paspalum turf and patches of young (l-2 m. high) mangrove along the several small pools and ditches. The meadow is bordered with high Guinea grass, and in the immediate surroundings are several unusual large palms, oaks, and strangler figs. Groundsel-bush (Baccharis halinzifolia), a 2-3 m. high shrub belonging to the composite family, is found at many places along the road and is especially common on the edge of the meadow.