There are about 70 species of anthocorid bugs in North America. These tiny predators, also known as flower bugs, reproduce more rapidly than do most other common predaceous insects. They can develop from egg to adult in as little as 15 days. Both adults and nymphs suck body fluids from their prey. The most common predaceous anthocorid is the minute pirate bug, Orius tristicolor, but three species of Anthocoris may also be abundant in fruit orchards. Anthocoris nemoralis is a European species introduced into North America as a predator for pear psylla.
Anthocorid bugs attack spider mites, thrips, aphids, young scales, pear psylla and eggs of various insects. Anthocoris spp. are particularly well adapted for feeding on pear psylla and can play a major role in the biological control of this pest.
The egg is elongate and creamy white when first laid and is about 1/25 inch (1 to 2 mm) long. It is inserted into leaf tissues just beneath the epidermis, causing a bump. The white cap, or operculum, is the only part of the egg that is visible. The pattern on the cap is unique for each Anthocoris species.
The young nymph is yellowish to orange. The older nymph has a yellow to orange head and thorax with an amber colored abdomen and grows to about 1/4 inch (5-6 mm) in length.
The adult is mostly black with white markings on the wings. Orius tristicolor adults are about 1/16 (1.5 mm) long, while Anthocoris spp. adults are 1/8 inch (3 mm) long.
Anthocorids overwinter as adults in sheltered places, such as in trash, under tree bark, or under boards. They appear early in the spring, and females insert eggs into plant tissue. There are 3 to 4 generations each year. Nymphs and adults have piercing and sucking mouthparts enclosed in a long beak. They will occasionally probe the plant with their beaks, but this does not appear to cause damage.
Adults and nymphs can be monitored in orchards with beating trays.
Anthocorids can be released in orchards and often will remain there year after year. They appear to have developed a tolerance to some insecticides, such as azinphosmethyl, chlorpyrifos, amitraz and oxythioquinox, but they are very susceptible to pyrethroids.