Amblyseius andersoni Slow-Release Prevention Sachets

The all-weather generalist. Amblyseius andersoni works across a wider span of conditions than any other predatory mite we carry — active from 43°F to 100°F with no winter dormancy — and eats spider, broad, cyclamen and eriophyid mites, the russet and rust mites almost nothing else will touch. When the room swings and the specialists stall, this is the one still on shift.

Inside is a breeding colony, not a dose. Eggs, nymphs and adults develop in the medium and leave through a vent over about four to six weeks. Pollen keeps the colony fed, so you can hang it before pests arrive and it establishes and waits.

And it asks nothing of you. Nothing to mix, nothing to spray, no residue on the leaves, no re-entry interval and no dose to get right — you hang it on a stem and leave it. No loose carrier on your foliage, nothing to keep children or pets away from, and nothing these mites can develop resistance to. Safe around people, pets and anything you plan to eat.

Sachets are prevention, not treatment, and they are deliberately slow. If you already have webbing, stippling or visible damage, a sachet will not save the plant — you need loose mites from a bottle for that. Start with persimilis, the andersoni bottle or Spider Mite Rapid Response, then hang sachets afterwards to hold the line.

Best for: A space you cannot climate-control, where a cold snap or a heat spike does not stop it. And broad mites on hoyas and begonias — twisted, hardened new growth is where these earn the order.
How many: One every three to five linear feet. Sold as single sachets, with discounts on quantity.
Placement: Attach to a stem, stake or trellis near the foliage — not down at soil level. Do not open it; once the medium is wet or exposed the colony is finished, so keep irrigation and misting off the paper.
Replace: Every four to six weeks while the season is active.
How you'll know: You won't see them, and the sachet looks identical on the day you swap it as on the day you hung it. That is normal, and it is not a way to tell whether it is working. Measure the plant instead — the newest leaf is the only honest report card.
Safe around: People, pets, plants and food crops.
Not for: Rescue. And if your room is stable, warm and humid, swirskii or limonicus will out-eat it — andersoni's advantage is tolerance, not appetite.

First, make sure a sachet is what you want

Sachets are prevention, not treatment. Mites breed inside the sachet and trickle out over four to six weeks, keeping numbers down before a problem starts. They are deliberately slow.

If you already have webbing, stippling or visible damage, a sachet will not save the plant. You need loose mites from a bottle for that — start with Persimilis, the andersoni bottle or the Spider Mite Rapid Response, then hang sachets afterwards to hold the line.

What is actually inside

A breeding colony, not a dose. Eggs, nymphs and adults develop inside and leave over four to six weeks through a vent in the paper.

• Do not open the sachet. The medium inside is what keeps the colony producing. Once it is wet or exposed, the colony is finished.

• Keep irrigation and misting off the paper. Same reason.

• You will not see them. The sachet looks unchanged from the day you hang it to the day you swap it. That is normal and is not a way to tell whether it is working.

How to hang them

• Unpack on arrival. If you must wait, somewhere cool for no more than a day or two.

• One every three to five linear feet.

• Attach to a stem, stake or trellis near the foliage — not down at soil level.

• Swap every four to six weeks while the season is active.

The sachet guide covers the rest.

When this is the right sachet

• Deploy before webbing. This is a shield, not a rescue. Hang it early in the season, or straight after a knockdown.

• Garages and unheated rooms. Cold nights and hot afternoons in the same day are exactly what this one is built for.

• Broad mites on hoyas and begonias. Twisted, hardened new growth is where these earn the order.

• Flowering plants. Pollen keeps the colony fed, so hang it before pests arrive and it establishes and waits.

• Stacked with persimilis. Persimilis covers spider mites through the warm humid stretch; andersoni covers the cool nights and the mites persimilis ignores.

Depends what you sprayed. Residue kills them on the way out of the vent. Neem and horticultural oil are contact only; insecticidal soap needs a day; sulfur is 21 days; a synthetic pyrethroid is 8 to 12 weeks.

What working looks like

Uneventful new growth. No stippling, no bronze rough leaves, no deformity at the crown. Because the sachet itself never changes, measure the plant instead — the newest leaf is the only honest report card.

Worth reordering?

Andersoni is the one to reorder for a space you cannot climate-control. If your room is stable, warm and humid, swirskii or limonicus will out-eat it — andersoni's advantage is tolerance, not appetite.

Not sure which one? Reach out to our bug pros at fgmnnursery.com/order-support. Tell them what the plant looks like and what the room runs at, and they'll pick for you.