Novaluron (Rimon 10EC) is a novel insect growth regulator with potent insecticidal activity against the Colorado potato beetle, Leptinotarsa decemlineata. The predatory bug Podisus maculiventris is a natural enemy of L. decemlineata found throughout North America, and is widely available commercially. Anticipating the use of novaluron in L. decemlineata management, we conducted laboratory experiments to determine the susceptibility of P. maculiventris to novaluron. Although there was a 2-3 day delay in the onset of toxic effects, 2nd instars were susceptible to novaluron both by direct contact exposure, and through exposure to potato foliage treated with rates of novaluron recommended for control of L. decemlineata. When P. maculiventris eggs were dipped in field rate novaluron solutions, there was no significant effect on percent hatch, but there was subsequently a sharp decrease in the ability of hatched nymphs to molt. Similarly, 5th instars actively preyed upon L. decemlineata larvae dipped in field rate novaluron solutions, but were thereafter unable to molt into adults. Adult P. maculiventris mating pairs caged with L. decemlineata larvae and novaluron treated potato plants lived just as long as those caged with untreated potato plants. However, oviposition and hatch of eggs from adults on novaluron treated plants was significantly reduced. Although novaluron has demonstrated selectivity in favor of beneficial insects in other studies, these results suggest that P. maculiventris would be adversely affected by exposure to the compound.