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The Mighty Minute
Pirate Bug | 22
True to their name, the Minute Pirate Bug (Orius tristicolor)
is a tiny, pinhead-sized, voracious insect predator whose
beneficial impact is quite out of proportion with their
minuscule size. They are important natural enemies of pests
of many agronomic and horticultural crops including cotton,
corn, sorghum and soybeans. Both the adults and nymphs are
active predators and feed on thrips, spider mites, aphids
and small caterpillars, exerting a predatory influence throughout
the entire season. When there is an abundance of prey in
one area, they are able to gather quickly and can consume
30 or more spider mites per day!
Life Cycle
Adult Minute Prate Bugs are oval-shaped, about 3 mm long
(or 1/8”), very flat, and are black colored with white
wing patches. Nymphs are small, wingless insects, yellow-orange
to brown in color, teardrop-shaped and fast moving. Nymphs,
like those of other true bugs, pass through five instars
before becoming adult. Approximately 19 days are required
to complete the nymphal stages and with each stage they
increase in size and begin to look more like adults. Both
adults and nymphs feed by sucking juices from their prey
through a sharp needle-like beak, which is characteristic
of all true bugs.
The Minute Pirate Bug overwinters as an adult
in leaf litter both inside and outside orchards, under tree
bark or boards, around homes and other buildings. They are
most common where there are spring and summer flowering
shrubs and weeds, since they feed on pollen and plant juices
when prey are not available. To encourage their presence
year-round, field margin plantings in the carrot family
such as fennel, dill, Queen Anne’s lace, yarrow, sunflower,
buckwheat, coyote brush, alfalfa, corn, clover and vetch
are recommended.
Adults emerge in early spring and live for
3 - 4 weeks then lay their eggs in plant tissue. The nymphs
emerge in 4 - 5 days and become adults in 7 - 10 days. Three
to four generations may occur during the growing season.
This predator does not injure crop plants to any significant
degree. There are occasions when the adults will attempt
to penetrate human skin with their proboscis causing a mild
stinging sensation. Such instances are unusual and not severe.
Reduced Risk
Use of reduced risk pesticides such as Bts, applied
only when and where needed, will conserve the existing population
of flower bugs. Because these insects feed on plant sap
when prey is not available, systemic insecticides should
be avoided.
References: Berry, Ralph E., 1978. Insects
& Mites of Economic Importance in the Northwest. O.S.U.
Book Stores, Inc. Corvallis, Oregon.
Virginia Tech Entomology
Department Website: www.ento.vt.edu/Fruitfiles/orius.html
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