Broad Mite

A. cucumeris + A. swirskii.

Broad mites distort growth; predatory mites prevent outbreaks...

About Broad Mites

Broad mites (Polyphagotarsonemus latus) are microscopic, fast-moving pests that damage tender new growth on a wide range of ornamentals, soft fruit and protected edibles. Their feeding injects toxins into the plant, causing severe distortion, bronzing and stunting. Because they prefer young tissue and hide deep in buds and meristems, they are often missed until damage is advanced.

Symptoms of Broad Mite Damage

• Tight, hardened or distorted new growth
• Bronzed or glossy appearance on young leaves
• Stunted growth and reduced internode length
• Deformed flowers or aborted buds
• Leaf cupping and downward curling
• Microscopic “speckling” on underside of tender leaves

Why Biological Control Works

Broad mites thrive in warm, humid environments and reproduce extremely quickly, but their small size makes them ideal targets for predatory mites. Species such as Amblyseius cucumeris, Amblyseius swirskii and Amblyseius andersoni accurately locate broad mites within buds and young growth, suppressing populations before symptoms become severe.

Key UK Broad Mite Biology

• Microscopic (0.2 mm) and difficult to detect without magnification
• Prefer warm, humid environments (20–28°C)
• Hide in tight buds and meristems, not on leaf surfaces
• Lifespan is short, but reproduction is extremely rapid
• Common on chilli, pepper, cucumber, aubergine, fuchsia and ornamentals

IPM Recommendations

• Release predatory mites early in the crop cycle
• Maintain strong air movement to prevent humidity spikes
• Use sticky traps to detect related tarsonemid activity
• Inspect growing tips weekly using a 10–20× lens
• Avoid broad-spectrum insecticides which flare mite populations

Preventative vs Curative Strategy

Preventative:

• Apply Amblyseius cucumeris preventatively in propagation, potting-on and early crop establishment.
• Amblyseius swirskii provides season-long protection, especially in warm houses (25°C+).

Curative:

• Increase introduction rates of A. swirskii or A. andersoni when hotspots appear.
• Remove badly twisted or hardened buds to reduce pressure.

Environmental Notes

• A. cucumeris performs best in cooler conditions (18–26°C)
• A. swirskii outperforms all others in warm houses (22–32°C)
• A. andersoni is versatile and tolerates wider temperature ranges
• High humidity (>70%) favours broad mite reproduction
• Good airflow and canopy separation reduce outbreaks