Reference work entry
Frass is the solid excrement (fecal material) produced by various insects that feed on wood, foliage and other solid materials. Frass is produced in various shapes (Fig. 86), and moisture content varies with the diet. It is commonly produced in pellet form by various leaf-feeding caterpillars, sawflies and beetles, and the shape can be diagnostic of certain genera. The term is probably more widely used to describe excrement produced by various wood boring beetles and certain termites.
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