Abstract
Predators that have fed on Panonychus ulmi (Koch) and Bryobia arborea Morgan and Anderson can be distinguished by the orange and reddish carotenoid biochromes derived from the prey. Predation on the two species of mites cannot be clearly separated. The predators are squashed on filter paper and the pigments separated by circular chromatography in a mixture of one part of zylene to four parts of white kerosene. The mite pigments are considerably altered during digestion in the predators. The method does not reveal the number of mites consumed by a predator, owing to differences in the pigment content of the various stages of the prey and in the time the pigments are retained in the predators.