The Relation of AdultRhodnius prolixus(Reduviidae, Rhynchota) to Atmospheric Humidity

Abstract

1. The paper describes an experimental study on the effect of atmospheric humidity uponRhadnius. The work was carried out on fasting males of known age, kept at 23° C. at different relative humidities; the proportion of water was determined after the lapse of definite periods of time. The normal male contains 30 per cent. of dry matter.2. Taking the results after 42 days' starvation, at 30, 60 and 90 per cent. humidity, the weight of each group of bugs has fallen to 50 per cent. of what it was at the start of the experiment. Those kept in damp air have lost dry matter and water in the same proportion, so that the percentage of dry matter after starvation is still 30 per cent. of the total weight. Those kept in drier air lose more water but oxidise less dry material, so that the proportion of solids rises during starvation: in those kept at 30 per cent. relative humidity the proportion of solids rises to 39 per cent. The figures for insects kept at 0 per cent. humidity are consistent, but it is not possible to obtain them beyond the 32nd day.3. Death is probably due to a rise in the concentration of the body fluid and not to the exhaustion of food material. This is shown by the fact that the exhaustion of solid matter is actually less in dry air than in moist, though mortality is only observed among the bugs kept in dry air.