Shoreline mud in two southern California dairy ponds was subjected to three shading treatments: deep shade, partial shade (screen), and full exposure to the sun. Shading panels were positioned above the mud after sunset, and surface mud temperatures and samples were taken from just below the waterline the following day at 0700, 1000, 1300, 1600, and 1900 hours. Invertebrates were extracted by direct MgSO, flotation, and data from the five sampling days were analyzed.Culicoides variipennis(Coquilleu) larvae were the most prevalent insects recovered. No correlations ofC. variipenniswith Chironomidae, Corixidae, predatory Hydrophilidae, or Tabanidae larvae were detected. Numbers of all fourC. variipennislarval instars were significantly lower in all shading treatments at 0700 hours, and were highest at 1300 and 1600 hours. There was no interaction between time of sampling and degree of shading. The highest numbers of all larval instars were found in open mud, followed by partial shade and deep shade. Later instars were found in markedly lower numbers in deeply shaded mud, while numbers of first instars in deep shade were not significantly less than in the other shading treatments. Factors influencing larva movement are discussed.