Spacing behaviour by nymphs of Coenagrion resolutum (Odonata: Coenagrionidae) was studied in the laboratory. Solitary nymphs found and remained at feeding sites; when several nymphs were present some were excluded from feeding sites. Nymphal size had no effect on positioning of solitary nymphs at feeding sites, but when nymphs occurred together, large nymphs excluded smaller nymphs. Prior occupancy at a feeding site by a nymph did not enhance its chances of remaining there when an intruder was added. When presented with a number of feeding sites, solitary nymphs stayed at only one site as frequently as did nymphs presented with only one site. Results are discussed in relation to possible effects of spacing behaviour on zygopteran life history and predator–prey dynamics.