This study examined the effects of prey availability and the addition of plant material to the diet of a generalist insect predator (the stinkbug Podisus maculiventris). In the first experiment, third through fourth instar stinkbugs were fed a diet of mealworms (Tenebrio molitor), either one mealworm every day or one mealworm every five days. In addition, the stinkbugs had either no plant material, a green bean leaf or a slice of green bean pod. Final dry weight, developmental rate and relative growth rate were negatively affected by prey scarcity. In contrast, none of these variables were affected by the addition of plant material. In the second experiment, third instar stinkbugs through the adult stage were fed a diet of mealworms, with one every day, one every four days, or one every eight days. In addition, tomato leaves, celery leaves, basil leaves, or no plant material were provided. Fresh weight of newly ecdysed adults, developmental rate and relative growth rate of the nymphs were negatively affected by prey scarcity and plant supplement. Increasing prey scarcity reduced the total number of eggs produced by females, and egg developmental time was decreased. With addition of plant material, females laid more eggs, but weight of first instar progeny was lower. The use of plant material and the trade-off between increased egg production and reduced progeny weight may help to explain how populations of this predator survive during periods of low prey density.