Studies of the Responses of the Female<i>Aëdes</i>Mosquito. Part III. The Response of<i>Aëdes aegypti</i>(L.) to a Warm Body and its Radiation

1. A warm object is more attractive to the female yellow-fever mosquito than a cooler object, such that the numbers touching a ball warmed to 100° or 110°F. were twice as great as those touching a ball 20°F. cooler. This attractiveness was reversed when the temperature of the warmer ball reached 120°F. 2. This response is eliminated by the insertion of an air-tight window of thallium bromoiodide, despite the fact that it allows almost all of the radiation to filter through. It is therefore concluded that heat convection, which is eliminated by the air-tight window, is the factor which makes a warm object attractive to the mosquito. 3. The several faces of a warm cube, differing in their radiant emissivity but identical as to surface temperature, exhibited attractancies to Aëdes which were not significantly different one from another (except in the case of black enamel, which will be explained in a later paper). These results may be interpreted to indicate that radiation plays no part in the attraction of the mosquitos to the warm face. 4. It is concluded that the failure of Parker (1948) to obtain a positive response of Aëdes mosquitos to a warm dry object was due to the fact that his apparatus allowed only the radiant heat but not the convective heat to reach the insects. 5 Since the response of Aëdes aegypti to heat is eliminated by a window transparent to infra-red radiation, the theory of olfaction proposed by Beck and Miles (1947) evidently has no application to this species of mosquito.