The concentrations of cadmium, copper, nickel and lead were studied in two biennial pine insects in relation to the deposition of heavy metals in the environment around the industrialised town of Harjavalta in southwestern Finland. Sap-sucking pine bark bugs, Aradus cinnamomeus (Heteroptera, Aradidae), and gall-forming pine resin gall moths, Petrova resinella (Lepidoptera, Tortricidae) were collected on sample plots located at logarithmic distances along 9 km-long transects from the distinctive emission source. The responses of these insects representing different life-style were compared. Heavy metal concentrations in A. cinnamomeus were highest (Cd 17 microg g(-1), Cu 1900 microg g(-1), Ni 220 microg g(-1), Pb 32 microg g(-1)) in the vicinity of the factor complex, and lowest in the outermost zones. This trend followed a linear regression model. The pattern was less clear in P. resinella, the concentrations being only one-tenth of those recorded in A. cinnamomeus. Correlations between metal levels in A. cinnamomeus and previously examined Sphagnum moss bags proved to be highly significant in every case. The differences in the heavy metal concentrations of these two insect species, which occupy the same trophic position, would appear to be due to the differences in their feeding characteristics. Heavy metals accumulate in the posterior bulb of the midgut in the discontinuous alimentary system of A. cinnamomeus, while P. resinella is likely to secrete most of the metals into the walls of the galls. The almost total absence of these two insect species near the factory complex seems to be associated with the high concentrations of metals.