A 0.4% black sand granular and a briquette formulation of methoprene (Altosid) were tested as preflood and residual applications in brackish water ponds against Aedes taeniorhynchus (Wied). In the preflood applications, samples of the sand granular formulation at 0.02 Ib. AI/acre were exposed to sun and rain for 2, 9, 16, and 23 days before flooding. In these tests the formulation remained effective for at least 2 days after being exposed. When tested at weekly intervals for residual activity, the granular formulation was not effective 7 days after initially flooded. Preflood applications of the briquets at a rate of 1 per 100 ft2, which had been exposed for 7, 14, 21, and 28 days before flooding, were still effective at 28 days. The unexposed briquets applied at the same dosage and tested at weekly intervals for residual activity remained effective for 31 days.