A peculiar erythemato-vesicular dermatitis, that appears mostly in the uncovered areas of the body, has been observed in Caracas, Venezuela. The clinical characteristics of the condition are those described in connection with the vesicant properties of coleoptera of the genus Paederus. Paederi are present in the area, and experimental lesions are similar clinically and histologically to the natural dermatitis. The widespread distribution of these insects and their role as a cause of discomfort is emphasized.