A new more effective technique for separating Culicoides immature stages from mangrove mud is described. This procedure utilizes an inverted funnel unit and hypersalinization of the mud sample. The effects of light, variations in salt concentrations, and frequency of decanting are reported and the method is compared to the previously used sand-layer technique. Best yields were obtained when the inverted funnel units were shielded from the light. A 150 g/I NaCl solution was optimal in achieving rapid and thorough separations of both larvae and pupae. It was found that decanting each unit 3 times at half-hour intervals after an undisturbed 1 hr period gave the quickest larval separation, but yields of over 90% could be obtained by decanting only once after a 3 to 4 hr quiescent period. The method gave significantly higher yields in less time than were obtained with the sand-layer method. The procedure may also find application in the separation of other motile invertebrates from littoral and benthic samples from a variety of habitats, ranging from freshwater to marine.