Amblyseius swirskii
A pale, pear-shaped predatory mite 0.5–1 mm long, sold in bottles or slow-release sachets. It eats young thrips larvae, whitefly eggs and young larvae, and broad mites, and it also feeds and breeds on pollen, so it can be put in before the pest and hold on. It needs warmth: Koppert says it is not effective below 18 °C, and it is not for tomato.
At a glance
- Size
- 0.5–1 mm; cream to pale yellow
- Rate
- 25–100 /m²; 100–300 on hot spots
- Ships as
- Bran in bottles, or sachets
- Temp
- 20–32 °C; not below 18 °C
- Humidity
- Above 60% (Biobest: around 50%)
- Sachets last
- About 4–6 weeks
How it works
The mite pierces its prey and sucks it out. It takes the small stages: first-instar thrips larvae, whitefly eggs and the first two larval stages, and broad mites, with spider mites a lesser prey. Arbico puts its appetite at about ten thrips or whitefly larvae, or up to twenty whitefly eggs, a day. At 25 °C it goes from egg to adult in about five to seven days, and it breeds on pollen as well as prey, which is why it can be released before the pest and still be there when it arrives.
Its limits are climate and leaf surface. Koppert and Cornell give 20–32 °C as its range and Koppert says it is not effective below 18 °C, so it suits warm houses and summer crops; in a cool spring house the cucumeris mite is the usual choice. Koppert and UConn say not to use it on tomato, and Cornell calls it likely ineffective there because of the glandular hairs on the leaves. Released with Neoseiulus cucumeris, the two tend to eat each other, so choose one.
Is it established?
What a working release looks like. Look on the undersides of leaves and in the flowers with a hand lens; it is hard to pick out by eye on the plant.
- DAY 1Pale, fast-moving mites on the leaves where the carrier landed, or around the sachet
- WEEK 1–2Tiny oval cream-coloured eggs, about 0.15 mm, on leaf undersides — the mites are breeding in the crop
- WEEKS 2–4Fewer young thrips larvae and whitefly eggs on the leaves you check
- WEEKS 4–6Sachets are spent; replace them if the pest is not under control
Release & handling
The mites are live and do not keep. Use them on the day they arrive; Koppert allows 1–2 days at 10–15 °C in the dark, with ventilation so carbon dioxide does not build up. Never refrigerate, and keep the bottles and sachets out of direct sun.
Cool, dark, ventilated
10–15 °C, bottles on their side. Use within a day or two; some retailers say within 18 hours.
Turn, then sprinkle
Shake gently to mix the mites through the bran, then sprinkle onto the leaves where it will stay for a few hours.
Hang in the shade
Hold by the card strip, not the pouch. Hang in sheltered spots out of direct sun. Koppert: at least 4,000 per hectare.
Repeat at four weeks
Koppert repeats sachets after four weeks if the pest is not controlled. Keep the humidity up.
Pesticide sensitivity
Cornell lists abamectin, deltamethrin and spinosad as harmful, and Bt, diamides, diflubenzuron, methoxyfenozide and pymetrozine as compatible. Check the supplier's side-effects list for the product you use. Check a product →
When to choose something else
A warm-crop preventive. Choose something else when:
- The crop is tomato — it does not establish on tomato leaves; for whitefly there, use a parasitoid such as Encarsia
- The house runs below about 18 °C — Neoseiulus cucumeris works from 15 °C
- You are already releasing N. cucumeris — the two eat each other, so use one or the other
- Adult thrips are the problem now — it eats larvae; Orius bugs take adults
- Spider mites are the main pest — it takes them only as minor prey; Phytoseiulus persimilis is the specialist
Where to buy
Suppliers listed alphabetically, not ranked. helpfulbugs takes no commission and does not sell insects.
- Arbico Organics25,000 to 125,000 loose; sachets on hooks or sticksUS
- BioBee (BioSwirski)25,000 / 50,000; sachets of 250IL / EXPORT
- Buglogical25,000 / 50,000 loose; boxes of 100 sachetsUS
- Dragonfli5 to 500 sachetsUK
- Koppert (Swirski-Mite, Swirski Ulti-Mite)50,000 / 250,000; 100 or 500 sachetsGLOBAL
Amblyseius swirskii by target
Rate and timing differ by what you are releasing it against. Each page below is the program for one pest.