Orius insidiosus
A 2–3 mm black-and-white true bug, found wild from the eastern US south into Latin America, and the species US suppliers sell as the minute pirate bug. Adults and nymphs spear thrips, spider mites, aphids and insect eggs and suck them dry, and it is one of the few predators that kills adult thrips. You can buy it for greenhouses, but it is also one of the commonest wild predators in gardens and fields. It is also the tiny bug that bites bare arms on warm days in late summer.
At a glance
- Mode
- Predator — adults and nymphs
- Rate
- 1–2 /m² typical; 0.5–10 /m² (Koppert); Arbico up to about 20 /m² for heavy infestations
- Ships as
- 500–2,000 adults and nymphs in a carrier
- Temp
- Best above 20 °C; 18–28 °C
- Day length
- Stops breeding below about 12–14 h
- Setting
- Greenhouse; also wild outdoors
How it works
Orius finds prey by touch, grips it with its front legs, pushes in its beak and drains it. It often kills more than it eats. Koppert puts an adult female at about 20 western flower thrips a day and Buglogical at 12. Cornell says adults and nymphs can each take 30 or more spider mites a day. It also feeds on pollen and plant juices, which UF/IFAS says improve its survival, so it can build up in flowering crops such as sweet pepper before thrips arrive. In UF/IFAS work on pepper, one bug to about 180 thrips suppressed the thrips and one to about 40 held them below the economic threshold.
Females insert their eggs into plant tissue. They hatch in six to ten days, the nymphs pass through five instars, and egg to adult takes about three weeks. Adults then live three to four weeks. Nymphs are yellow-orange to brown, teardrop-shaped with red eyes. The species relies on day length: UF/IFAS and Cornell say adults stop breeding when days are shorter than about 14 hours (Virginia Tech gives 13, Buglogical 12). Under natural autumn and winter day lengths, released bugs may feed but will not build a population.
Outdoors it occurs wild. It is common in the Midwest and East, where it is also called the insidious flower bug; in the western US the related O. tristicolor is more common, and both go by minute pirate bug. Adults overwinter in leaf litter, bark and buildings. In late summer and early autumn, as flowers dry and prey declines, they probe bare skin. Iowa State calls the bite surprisingly painful for such a small insect; Cornell says bites are rare and only mildly, briefly irritating. Iowa State and Minnesota Extension say they do not feed on blood, inject venom or spread disease. Any swelling passes, and controlling them is neither practical nor wanted.
Is it established?
Adults are easy to see on the day of release. After that the proof is nymphs, and they are in the flowers. Look there first.
- DAY 1Black-and-white adults, about 3 mm, on leaves and flowers near the release points
- WEEK 1–2Sucked-empty thrips, then the first small yellow nymphs with red eyes
- WEEKS 3–4Nymphs of mixed sizes and a new generation of adults in the flowers
- AFTERFewer thrips per flower; if no nymphs are found, release once or twice more
Release & handling
Bugs arrive as adults, or adults and nymphs, in a bottle of carrier such as corn grit or vermiculite. Release them on arrival. Suppliers disagree on how to hold them if you must: Koppert says 10–15 °C in the dark for one to two days, while Arbico and Bioline say 6–10 °C and use within 18 hours.
Release the same day
Keep the bottle out of the sun. If there is a delay, store it dark and horizontal, at the supplier's temperature.
Roll, don't shake hard
Tilt the bottle on its side and turn it gently so the bugs are spread through the carrier.
Groups of 50 or more
Put small piles on leaves, rockwool or release boxes in and around thrips hot spots, early or late in the day.
Leave the piles alone
Leave the piles alone for a few hours so the bugs can disperse and mate. Repeat the release once or twice.
Pesticide sensitivity
UF/IFAS says broad-spectrum pyrethroids, neonicotinoids, organophosphates and carbamates eliminate Orius populations, and that populations can be conserved through careful use of reduced-risk insecticides such as spinosad. Check a product →
When to choose something else
Pirate bugs are the thrips predator that takes adults, but they have limits. Choose something else, or add to them, when:
- Days are short — below about 14 hours the bugs stop breeding, so rely on predatory mites such as Amblyseius cucumeris through winter
- The crop is tomato — Koppert advises against Orius in tomato
- The crop has no pollen and few thrips yet — the bugs have nothing to live on; start with predatory mites
- You grow outdoors — UC IPM says releases outdoors are unlikely to control pests; conserve the wild pirate bugs by planting flowers and avoiding broad-spectrum sprays
- You are in Europe — suppliers there mainly sell Orius laevigatus
Where to buy
Suppliers of Orius insidiosus listed alphabetically, not ranked. helpfulbugs takes no commission and does not sell insects.
- Arbico Organics500 / 1,000 / 2,000US
- BioBee (BioOrius)500 / 1,000 / 2,000US / CA
- Bioline AgroSciences (Oriline i)500 / 1,000 / 2,000US / CA
- Buglogical500 / 1,000 / 2,000US
- Koppert (Thripor-I)2,000US / GLOBAL
Orius insidiosus by target
Rate and timing differ by what you are releasing it against. Each page below is the program for one pest.