Spined soldier bug

Podisus maculiventris

Podisus maculiventris is a large predatory stink bug, the adults of which are approximately 11-13 mm long, with males usually being slightly smaller than females. The adults are pale brown in colour, with two prominent thorn-like ‘spines’ projecting to each side just behind the head. First instar nymphs are red and black and are usually found clustered close to the eggs from which they hatched. The nymphs gradually become more colourful as they develop, with paler areas that form partial bands around the abdomen. All stages are predatory except the first instar nymphs, which are not thought to feed.

The recorded prey range of P. maculiventris includes more than 80 insect species, of which approximately 50 are economic pests. Usually it is the immature prey stages that are attacked, with various beetle and moth larvae being commonly consumed. However, P. maculiventris will also attack the immature stages of some herbivorous stink bugs, squash bugs, the larval stages of some fly species, and various others, including the larval and/or adult stages of some coccinellid beetles. Moisture is needed for optimal survival and reproduction, and if prey or water is scarce they may feed on plant sap; however, such feeding does not cause noticeable damage to the plant.

The optimum temperature range for P. maculiventris lies between 22 to 27°C (72—81°F); at 24°C, the life-cycle (egg to adult) is completed in approximately 28 days, and adults may live 30—60 days at this temperature. With adequate prey, females are capable of laying more than eggs, usually in small groups on the underside of leaves.

Towards the end of the summer, older nymphs that develop under short-day conditions* will develop into adults that are in reproductive diapause, during which reproduction is suspended and predation rate is reduced. Diapause is an adaptation for overwintering and is reduced or prevented at higher temperatures and longer day-lengths.

* At temperature of 23°C, ‘short-day conditions’ for this species equate to a period of about 10 days at a day-length of approximately 8 hours.