Behavior of Thoracic Spiracles of Aedes Mosquitoes1 in Controlled Relative Humidities

Observations were made on the behavior of the thoracic spiracles of A. triseriatus (Say) and A. aegypti (L.) in high (90±5%) and low (<5%) relative humidities. Following a 5-minute exposure to low relative humidity, spiracular responses to 0.5% carbon dioxide were reduced in both species while only A. triseriatus showed attenuated spiracular behavior after a 2-minute exposure. Conservative spiracular opening was observed in both unfed and fed mosquitoes. It is postulated that the spiracular response to low relative humidity is a sensory one.