The Ingestion of Dry Sugars by Adult Entomophagous Insects and the Use of This Feeding Habit for Measuring the Moisture Needs of Parasites1

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Abstract
The belief that adult insect parasites must acquire their foods from liquid or semifluid sources has made it difficult to assess accurately the moisture needs of different entomophagous species. It was found that many adult entomophagous insects can feed upon completely dry sugar. Parasitic Hymenoptera dissolve the dry sugar with a lapping movement of the glossa moistened with salivary fluids. Some adult predators use regurgitated fluids for dissolving the sugar before its ingestion. By comparing the survival of adult parasites supported on dry sugar at 0% relative humidity with that of adults given moist sugar at optimum moisture conditions, the aridity tolerance of a species may be assessed without interference by starvation or by liquid food intake. Examples of the use of this simple method for assessing the moisture needs of four species of parasites are presented.