Borates are of potential use in the development of baiting systems for subterranean termite control. In the 15-day laboratory assays reported here, the oral toxicity of disodium octaborate tetrahydrate to Reticulitermes flavipes (Kollar) was evaluated under choice and no-choice conditions. These assays suggest a range of 2500 to 5000 ppm to be applicable in developing baits, and that concentrations greater than 5000 ppm may deter feeding. Laboratory assays with borate dusts (disodium octaborate tetrahydrate, zinc borate, and a fine-grain zinc borate) are also reported. In a toxic variation of mark-release methodology, these materials are passed among the test group by grooming foragers exposed to the dust. In these assays, 10% of the test group was exposed to the borate dust, then released placed in contact with unexposed workers in a simulation of a field release. Zinc borate treatment elicited the greatest mortality (99-100%), although disodium octaborate tetrahydrate also elicited mortality significantly greater than that in the control groups. These results suggest that less soluble borates may be more efficient dust toxicants, and that capture and dust-treatment of a portion of the foraging termite population could elicit high mortality among termites contacting the treated individuals after their release back into the colony.

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