The migratory behaviour of salt marsh mosquitoes: Revisiting the evidence

In the early 1950s, approximately 1.5 million radiolabelled black salt marsh mosquitoes (Diptera: Culicidae, Aedes taeniorhynchus Wiedemann) were released from a point source on Sanibel Island, part of an archipelago of barrier islands and mangrove swamps off the southwest coast of Florida, during one evening in June (Provost, 1957). Carefully synchronising the timing of larval hatch in outdoor tanks filled with water from local marshlands, the research team orchestrated a mass emergence of adults and witnessed that “wisps of mosquitoes took off spontaneously in puffs”. After sunset, newly emerged Ae. taeniorhynchus adults resting on nearby surfaces gradually departed, and before dawn “the great mass of mosquitoes had gone”. In the following days, adults were recaptured using light traps distributed across the archipelago (Figure 1). Recapture rates of females marked with radiolabelled phosphorous-32 (p32) vastly outweighed those of marked males, with the latter concentrated within just a few kilometres. Marked females, however, were found up to 40 km from the release point, mostly downwind, and significant numbers made open-water crossings at least three kilometres in length shortly after release.