Stratiolaelaps scimitus
Formerly widely known as Hypoaspis miles.
Overview
Stratiolaelaps scimitus is a soil-dwelling predatory mite used in biological control programmes against sciarid flies, shore flies and other pests associated with growing media.
It is one of the most widely used soil predators in horticulture and forms the foundation of many preventative substrate-based IPM programmes.
Type
Soil predatory mite.
Target pests
Primary targets
- Sciarid fly larvae
- Fungus gnat larvae
Secondary targets
- Shore fly larvae
- Thrips pupae
- Vine weevil eggs
- Other small soil-dwelling organisms
Identification
Adults are small brown predatory mites that move rapidly through growing media and substrate surfaces.
They are rarely seen on foliage and spend most of their life within the upper substrate layer.
Why Stratiolaelaps is Important
Many important pests spend part of their lifecycle in the growing media.
Stratiolaelaps provides continuous predation within this zone and can help prevent pest populations becoming established before damage is visible above ground.
Environmental Requirements
Moisture
Performs best in evenly moist growing media.
Very dry substrates reduce activity and survival.
Temperature
Moderate protected-crop temperatures favour establishment.
Substrate
Works best where predators can move freely through the upper substrate layer.
Crops Commonly Used In
- Herbs
- Lettuce
- Ornamentals
- Strawberries
- Young plants
- Propagation crops
Strengths
- Excellent preventative predator
- Long-term establishment possible
- Compatible with many biological programmes
- Targets multiple soil pests
- Suitable for propagation systems
Limitations
- Works best preventatively
- Less effective against large established infestations
- Sensitive to prolonged dry conditions
- Requires even distribution
Works Well With
Common Reasons for Failure
Dry Substrate
Predators become less active and survival declines.
Introduced Too Late
Heavy larval populations may require additional biological controls.
Uneven Distribution
Hotspots can persist if predators are not spread effectively.
Chemical Disruption
Some pesticide residues may affect survival.
Practical IPM Strategy
- Introduce early in the crop.
- Maintain suitable substrate moisture.
- Monitor sciarid fly activity.
- Combine with nematodes where pressure increases.
- Support with good hygiene and algae management.