Although pirate bugs (Orius) appear to have preferences for particular prey, they are general predators and will consume a variety of pests including mites, thrips, aphids, and small caterpillars.
The pirate bug Orius seems the most voracious beneficial against thrips. It is the only predator that also attacks adult thrips, Often an Orius with thrips stuck on its rostrum can be seen walking on a leaf.
The total gereration time for Orius in greenhouses (70 deg F) is approximately 3 weeks. Eggs are laid in plant tissue (main stem, leaf veins, flowers or petioles) with the top of the egg sticking out of the leaf. The eggs hatch in 4-5 days and grow through 5 stages.
All stages move quickly and adults are good flyers. They will move efficiently throughout the greenhouse to locate pests. Orius kills its prey by piercing them with its mouthparts, and sucking out the body fluids. If prey is abundant, Orius kills more thrips than it needs to survive. The generation time is affected by temperature and food sources. Cooler temperatures slow development, and the presence of pollen appears to have a favorabe effect on its development.
Release 100 to 2,000 Orius per acre. For greenhouse cucumbers, release 1 Orius per 2 plants for the whole greenhouse or 1 to 4 Orius per plant in hot spots, where thrips populations are established. It is recommended to release a minimum of 200 to 500 at one time even for smaller areas.
Orius insidiosus, also called the minute pirate bug, is an aggressive thrips predator – possibly the most effective. It attacks and kills all mobile stages of thrips, including adult thrips. Orius is aggressive – it consumes 12 thrips per day but kills many more (45) than it eats.
Orius is common on many agricultural crops including, alfalfa, corn, pea, strawberry, on pasture land, in orchards, and is successfully used as a biological control agent in greenhouses. It is often found in corn silks and is most common where there are spring and summer flowering shrubs and weeds since it feeds on pollen and plant juices when prey are not available. In greenhouses, Orius spp. are generalist predators, especially on cucumber and bell pepper crops. Both immature stages (nymphs) and adults feed on a variety of small prey including thrips, spider mites, insect eggs, aphids, and small caterpillars. Orius holds its prey with its front legs and inserts its beak into the host body, generally several times, until the soft body is empty and only the exoskeleton remains. It has been reported to be an important predator of the eggs and new larvae of the bollworm and of spotted tobacco aphid, but it is believed that thrips and mites are the more basic part of an Orius diet. It can also be an important predator of corn earworm eggs which are laid on the silks. Other reported prey includes eggs and small European corn borers, corn leaf aphids, potato aphids, and potato leafhopper nymphs. Females lay tiny eggs 2-3 days after mating in plant tissues where they are not easily seen. These hatch into nymphs which develop through five nymphal stages. Egg incubation is generally 3-5 days, and development from egg to adult takes a minimum of 20 days under optimum conditions. Females lay an average of 129 eggs during their life spans, and adults live about 35 days. Several generations may occur during a growing season.