The spined soldier bug Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae) is a generalist predator that can alternatively feed on plant tissue to survive under prey scarcity. This research aimed to evaluate the effects of plant feeding forced by a shortage of prey on the survival and reproduction of P. nigrispinus on Eucalyptus urophylla S.T. Blake (Myrtaceae) plants in the field. Podisus nigrispinus adults were enclosed on branches of eucalyptus by using gauze bags. These adults were fed daily with Tenebrio molitor pupae (T1) or after 5 (T2), 10 (T3) or 15 (T4) days from mating to simulate prey shortage. The pre-oviposition period, number of egg masses, number and viability of eggs and longevity of females were evaluated. Females of P. nigrispinus had a longer pre-oviposition period and produced lower number of egg masses as the period of prey shortage increased. However, the average number of eggs per egg mass, emergence of nymphs and longevity of P. nigrispinus females were not affected by prey shortage. Females of P. nigrispinus can survive 15 days without prey by feeding on eucalyptus leaves and if it finds prey afterwards can still reproduce. This shows that plant feeding is a successful incidental strategy to survive periods of food scarcity (and thus increase the efficiency) of this predator as a biological control agent.