Thrips Slow Release Sachets (Amblyseius cucumeris)

Predatory mites for thrips prevention in greenhouses, polytunnels, and indoor growing. Amblyseius cucumeris is a naturally-occurring predatory mite that hunts thrips larvae and pupae in the soil and on plants. Because it's a preventative control, not a rescue treatment, you introduce it BEFORE thrips become a problem, or at the very first sign of them. Each sachet contains a slow-release breeding colony that emerges gradually over 4-6 weeks, giving continuous protection through the vulnerable growing period. Environmentally safe for people, pets, pollinators, and beneficial insects — genuinely the biological control that gardeners keep coming back to.

Understanding thrips — and why they're difficult to control

Thrips are tiny slender flying insects, only 1-2mm long, that hide in flower buds, leaf sheaths, and the crevices of new growth. Most UK gardeners first notice thrips through the damage rather than the insects themselves: distinctive silver flecking on leaves, distorted flower buds that fail to open properly, black frass spots (thrips droppings) on the underside of leaves, and virus transmission that can devastate valuable ornamentals. Common UK species include Western Flower Thrips (Frankliniella occidentalis), Onion Thrips, and Rose Thrips — the sachets work against all thrips species.

The reason chemical sprays fail against thrips is that the pest hides where sprays can't reach: inside flower buds during feeding, deep in leaf axils during resting, and in the soil during the pupal stage. Predatory mites are small enough to pursue thrips into all these hiding places — they crawl through leaf crevices, hunt in the soil surface, and reach the vulnerable larval and pupal stages that sprays can't touch.

What's in each sachet

• Breeding colony of Amblyseius cucumeris — approximately 1,000 predatory mites per sachet, actively reproducing inside the paper sachet using bran carrier and pollen substrate. The colony continues producing new mites throughout the sachet's active life
• Slow-release timing — mites emerge gradually through small openings over 4-6 weeks, providing continuous introduction rather than one large release. Prevents the boom-and-crash pattern of single-release biocontrols
• Weather-resistant paper sachet — designed to hang from plants or attach to canes. Survives normal humidity and light misting
• Live biological product — dispatched directly by Ladybird Plant Care at peak freshness for maximum viability

Choosing the right pack size

Rough guidance for your growing space:

• 4 sachets — a few houseplants, small conservatory collection, or trial pack to see how biological control works before committing to more. Introductory scale
• 10 sachets — standard domestic greenhouse (6ft × 8ft or smaller), moderate houseplant collection, or first application on a new polytunnel
• 20 sachets — larger domestic greenhouse (8ft × 10ft or 10ft × 12ft), extensive conservatory, or preventative treatment across multiple growing spaces
• 50 sachets — small commercial glasshouse, larger polytunnel, or serious allotment holder with multiple structures. Also good for anyone treating multiple times through the growing season (approximately 25 sachets per treatment, twice per season)
• 100 sachets — professional or commercial grower, larger commercial glasshouse operation, or shared community glasshouse. Best per-sachet value in the range
• 200 sachets — large commercial operation, multi-house nursery, or professional grower supplying wholesale. Bulk supply for continuous introduction across the growing season

Typical application rate is 1 sachet per plant or 1 sachet per square metre. Larger woody plants (chillies, aubergines, tomatoes) may benefit from 2-3 sachets per plant on a rotating basis through the season.

When and where to use

• Indoor / greenhouse / conservatory — year-round protection. Since indoor temperatures stay warm enough for both thrips and mites, you can start prevention any time and continue through the growing season
• Outdoor UK gardens — introduce from mid-May onwards once frosts have finished. Earlier introduction is possible in constantly-warm locations (south-facing walls, sheltered polytunnels). Amblyseius mites can survive on pollen until thrips appear, so early introduction prevents infestation from establishing
• Optimal conditions — predator mites thrive at 20-25°C with humidity above 65%. Standard greenhouse conditions during growing season provide these naturally
• Vulnerable crops to protect — chillies, peppers, cucumbers, tomatoes, aubergines, courgettes, ornamental flowers (particularly roses, chrysanthemums, gerberas), houseplants (especially those with new soft growth). Basically anything that thrips like, and thrips like most things

How to apply

1. Open your delivery immediately and inspect the sachets — they should be intact with visible carrier bran inside
2. Hang sachets on plants or attach to canes so they're within the plant canopy but not touching wet foliage
3. Distribute evenly across your growing space at approximately 1 sachet per plant or per square metre
4. Leave sachets in place for the full 4-6 week active period — don't remove them early even if you can't see the mites (they're 0.5mm long and pale, essentially invisible without magnification)
5. Replace sachets after 6 weeks for continuous protection through the vulnerable growing season

See the detailed instruction PDF for specific placement guidance, application timing, and troubleshooting.

Important limitation — existing infestations

These sachets are a preventative and early-stage control. Amblyseius cucumeris attacks thrips larvae and pupae but does NOT control adult thrips. If you already have visible adult thrips flying around your plants or established damage, you need a broader-spectrum control that also targets adults. Please contact us for advice on the appropriate rescue biological, or check our other pest control range for adult thrips controls. Use these sachets alongside such treatments, not instead of, once an infestation is established.

Safety and compatibility

• Completely safe indoors — no risk to humans, pets, or beneficial insects. Can be used in kitchen areas around edible plants without concern
• Compatible with other biological controls — works well alongside lacewings, ladybird larvae, and most other predatory beneficial insects. Multiple biologicals can strengthen overall pest management
• Not compatible with chemical pesticides — wait at least 2-3 weeks after any chemical treatment before introducing mites, and don't spray any chemicals during the mite's active period
• Beneficial insect safe — won't harm bees, hoverflies, ladybirds, lacewings, or other garden allies

Dispatched directly by Ladybird Plant Care. This is a live biological product, so dispatch is handled by our trusted partner Ladybird Plant Care at peak freshness — typically Monday to Wednesday for delivery within 2-3 working days. Live biologicals cannot be sent for weekend delivery (they would sit undelivered at depots), and dispatch timing follows their schedule to ensure the mites reach you in optimal condition. Please allow additional time compared to standard seed orders, and unpack sachets immediately on arrival.

The wider biological pest control approach. Predatory mites work best as part of an integrated biological pest management approach: prevention through good hygiene (removing weeds, cleaning between growing seasons), monitoring through sticky traps for early detection, and biological controls at the first sign of pests. We stock a range of complementary biological controls through our Ladybird Plant Care partnership — browse our Pest Control & Nematodes collection for the full range including nematodes for soil pests, predatory mites for other targets, and beneficial insect releases.