Surprisingly, we found harpacticoid copepods in decomposing litter on the forest floor, and in the redwood forest canopy up to 276'. Harpacticoid copepods are semi-aquatic microcrustaceans that occur interstitially in benthic sediments and groundwater. They were previously reported in wet leaf litter (although not in redwood forests), into which they presumably migrated from the groundwater. We obtained them from forest floor litter bags and from litter bags in the canopy at all three crown positions.This represented a first report of this organism in redwood forests and especially in the redwood forest canopy. The migratory scale of such colonisation was impressive. These copepods were approximately 0.008" long; their emigration to 276' represents a vertical displacement of 420,000 times their body length. Some harpacticoids are known to encyst during dry periods, and others presumably produce desiccation-resistant eggs. Colonisation of the upper canopy could therefore have occurred in stages, perhaps requiring many generations. Indeed, we think this most likely.