Natural Enemies Gallery

Minute Pirate Bugs

Hosts or Prey

Predaceous on mites and small insects

Identification

Adult minute pirate bugs have bulging eyes and an oblong to oval body that appears somewhat flattened on top. Adult Orius species are 1/12 to 1/5 inch (2–5 mm) long and black and white. Adult Anthocoris species are 1/8 to 1/5 inch (3–5 mm) long and mostly black, brown, or purplish.

Nymphs (immatures) are oblong to pear-shaped and commonly brown, orange, reddish, or yellowish. With Orius species, the eyes may be apparent as two red spots. In older instars the developing wings (wing pads) are oblong and partially cover the abdomen.

Eggs are oblong with a flattened, circular cap. They are inserted into succulent plant tissue so only the round top protrudes. An oblong swelling may be apparent in plant tissue where each egg occurs.

Lookalikes

Adult minute pirate bugs can be distinguished from most other true bugs (Heteroptera) by the absence of obvious veins or cells (vein-bordered areas) near the tip of the forewings. Damsel bugs have multiple, elongated cells (translucent areas segregated by veins) around the tip of the forewings. Plant bugs have one or two, closed cells near the tip of each front wing.

Life Cycle

Minute pirate bugs develop through three life stages. Eggs hatch into wingless nymphs, which develop through five, increasingly larger instars, which mature into adults without any pupal stage.

Minute pirate bugs have several generations per year. Development time from egg to adult is about 3 weeks during warm weather.

Habitat

Minute pirate bugs are one of the first predaceous insects to begin feeding early in the growing season. They are common in field crops including alfalfa, corn, cotton, small grains, soybean, and tomato and on herbaceous plants in gardens, landscapes, and wildlands.

Adults and nymphs feed through needlelike mouthparts, sucking the body fluids of their prey. Preferred prey include spider mites and thrips. Minute pirate bugs also feed on aphids, psyllids, small caterpillars, whiteflies, and insect and mite eggs. They feed harmlessly on pollen and plant juices and are not plant pests.

Commercial Availability

Orius species or other minute pirate bugs are sometimes purchased and released in commercial greenhouses to help control thrips. In most outdoors situations, purchasing and releasing minute pirate bugs is unlikely to control pests; conserving resident natural enemies is the most important strategy.

To increase the effectiveness of resident natural enemies and any that are released

  • Control ants and dust.
  • Grow flowering plants that provide nectar and pollen for adults (insectary plants).
  • Avoid the use of broad-spectrum and persistent insecticides and miticides (acaricides).

See Natural Enemy Releases for Biological Control of Crop Pests, Protecting Natural Enemies and Pollinators, and Vendors of Beneficial Organisms in North America for more information.

Species

At least 12 genera of minute pirate bugs occur in California. These include at least 6 Anthocoris species and 3 each Orius and Xylocoris species.

More Information

Scientific classification:

  • Phylum: Arthropoda
  • Class: Insecta
  • Order: Hemiptera
  • Suborder: Heteroptera
  • Family: Anthocoridae
Adult minute pirate bug, Orius tristicolor, feeding on an aphid.
Adult minute pirate bug, Orius tristicolor, feeding on an aphid. Credit: Jack Kelly Clark, UC IPM Program
Eggs of pirate bugs, Anthocoris sp., are inserted into leaf tissue. Only their white caps protrude. The yellow egg in this photo is a psyllid egg.
Eggs of pirate bugs, Anthocoris sp., are inserted into leaf tissue. Only their white caps protrude. The yellow egg in this photo is a psyllid egg. Credit: Jack Kelly Clark, UC IPM Program
Nymph of minute pirate bug, Orius tristicolor.
Nymph of minute pirate bug, Orius tristicolor. Credit: Jack Kelly Clark, UC IPM Program
Adult pirate bug, Anthocoris nemoralis, feeding on a nymph of eucalyptus redgum lerp psyllid, Glycaspis brimblecombei.
Adult pirate bug, Anthocoris nemoralis, feeding on a nymph of eucalyptus redgum lerp psyllid, Glycaspis brimblecombei. Credit: Jack Kelly Clark, UC IPM Program
Appearance and relative size of the last instar and adult of a minute pirate bug, Orius sp.
Appearance and relative size of the last instar and adult of a minute pirate bug, Orius sp. Credit: see large image