FROM PLANTING
Two-spotted spider mite
Yield loss shows above one mite per leaflet in the first months (UC IPM).
ReleasePhytoseiulus persimilis2–3 per plant on light infestations; 5 per plant at threshold (UC IPM)
Crop hub · Under glass · Commercial
Strawberry, protected
Strawberry production has been moving into greenhouses, and western flower thrips and two-spotted spider mite are two pests that cut yield there (Saito & Buitenhuis, 2024). Cover also removes the rain that holds spider mite back outdoors: a study in Norway and Brazil suggests tunnels may let the mite reach higher numbers where it is warm enough, though naturally occurring predatory mites may keep it in check.
The crop flowers through the season and is pollinated by bumblebees, which Koppert and Biobest both supply for strawberries. UC IPM's strawberry table gives several miticides, including abamectin and bifenthrin, its strictest honey bee rating: do not apply them to, or let them drift onto, flowering plants. That is one more reason to lean on predatory mites.
crop context · table-top strawberries under cover
Five pests to plan for
FROM FLOWERING
Western flower thrips
Feeds in the flowers and bronzes fruit around the cap; UC IPM finds it seldom economic in the field.
ON TRANSPLANTS
Cyclamen mite
Arrives on nursery plants; crinkles the crown leaves and dwarfs the fruit.
WARM SPELLS
Chilli thrips
A severe invasive pest of US strawberry; predator results in the field have been variable.
IN CONTAINERS
Black vine weevil
Grubs eat the roots and crown; plants in pots and other containers are most at risk.
Season calendar
NORTHERN HEMISPHERE · SPRING-PLANTED TUNNEL OR GLASS · QUALITATIVE| J | F | M | A | M | J | J | A | S | O | N | D | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Spider mite | Jan: Quiet | Feb: Building | Mar: Building | Apr: Pest pressure high | May: Pest pressure high | Jun: Pest pressure high | Jul: Pest pressure high | Aug: Pest pressure high | Sep: Building | Oct: Quiet | Nov: Quiet | Dec: Quiet |
| Thrips | Jan: Quiet | Feb: Quiet | Mar: Quiet | Apr: Building | May: Pest pressure high | Jun: Pest pressure high | Jul: Pest pressure high | Aug: Pest pressure high | Sep: Building | Oct: Quiet | Nov: Quiet | Dec: Quiet |
| Cyclamen mite | Jan: Quiet | Feb: Quiet | Mar: Building | Apr: Building | May: Building | Jun: Pest pressure high | Jul: Pest pressure high | Aug: Pest pressure high | Sep: Building | Oct: Quiet | Nov: Quiet | Dec: Quiet |
| Release window | Jan: Quiet | Feb: Release window | Mar: Release window | Apr: Release window | May: Release window | Jun: Release window | Jul: Release window | Aug: Release window | Sep: Release window | Oct: Quiet | Nov: Quiet | Dec: Quiet |
- Pest pressure high
- Building
- Release window
- Quiet
- Spider mite · high pressure Apr–Aug
- Thrips · high pressure May–Aug
- Cyclamen mite · high pressure Jun–Aug
- Release window · release Feb–Sep
Starter program
A starting point built from a Canadian cage trial and the UC IPM strawberry guidelines. Check the transplants before planting: both spider mite and cyclamen mite arrive on them.
- AT PLANTINGAmblyseius cucumerisSachets of 1,000 mites, placed a week after planting (before pests arrived) and renewed after 6 weeks, as in the Vineland cage trial
- AT PLANTINGNeoseiulus californicusSachets of 100 mites alongside the cucumeris, on the same timing; early releases also for cyclamen mite (UC IPM)
- AT FIRST MITESPhytoseiulus persimilis2–3 per plant; 5 per plant once counts reach threshold (UC IPM)
- IF THE HOUSE RUNS HOTAmblyseius swirskiiBeat P. persimilis against spider mite above 82 °F (28 °C) in a Saudi greenhouse trial published in 2026; the two together did best
- LATE SUMMERHeterorhabditis bacteriophora250k–500k /m² of growing medium while vine weevil grubs are young; medium at least 60 °F (16 °C) and moist for two weeks
Setting the house up
Protected strawberry programs are mostly won or lost at planting.
Inspect the transplants
UC IPM names infested nursery plants as the main source of cyclamen mite. NC State says to check transplants for spider mites and find out what miticides were used on them.
Protect the bumblebees
UC IPM rates most strawberry insecticides and miticides for honey bees; those with the strictest rating must not be applied to, or drift onto, flowering plants. Check each product before use.
Count leaflets weekly
UC IPM samples mid-tier leaflets. NC State's early-spring threshold is 5 or more mobile mites per leaflet.
Watch the temperature
In a Saudi greenhouse trial published in 2026, spider mite numbers rose with temperature, and A. swirskii outperformed P. persimilis above 82 °F (28 °C).