Stratiolaelaps scimitus, formerly known as Hypoaspis miles, is a soil-dwelling predatory mite used in biological pest control to target pests that develop in the growing medium. These mites naturally live in soil and actively hunt small insects and other organisms near the base of plants.

They are particularly effective at controlling fungus gnat larvae and thrips pupae, two pests that spend part of their life cycle in the soil or growing media. By attacking these stages underground, Stratiolaelaps scimitus helps break the pest life cycle before adults can emerge.

Because they live in the top layer of soil and search constantly for prey, these mites are commonly used in greenhouse crops, houseplants, propagation trays, and container production systems.

Here’s what they look like at different stages of their life:

Like other predatory mites, Stratiolaelaps scimitus develops through five stages: egg, larva, protonymph, deutonymph, and adult.

• Eggs: The eggs are small, white, and oval in shape, measuring roughly 0.3 mm long. They are laid directly in the soil or growing media near potential prey.
• Larvae: Larvae are tiny, pale in color, and have six legs. During this stage, they do not feed and quickly develop into the next stage of the life cycle.
• Nymphs: These juvenile stages have eight legs and begin actively searching for prey in the soil. They resemble smaller versions of the adults and gradually darken in color as they develop.
• Adults: Adult mites are relatively large for a predatory mite, reaching up to 1 mm in length. Their bodies are pale to tan with a noticeably darker dorsal shield and brown legs. Females are slightly larger than males and often show a pale stripe near the rear of the body.

Behavior:

• Most activity occurs in the top 1–2 cm of soil, where the mites search for prey around plant stems and root zones.

Why growers love it:

• Targets pests that develop in the soil
• Controls fungus gnat larvae and thrips pupae
• Works preventively or curatively
• Survives on alternative soil organisms when pests are scarce
• Compatible with many IPM programs
• Safe for plants, people, and beneficial insects

Timing is critical to achieving success with predatory mites. They perform best when introduced before pests reach outbreak levels.

Preventive Use:

• Ideal to introduce early in the crop cycle at planting or when re-potting .

Curative Use:

• At the first signs of fungus gnat or thrips activity.
• When there is a high infestation of fungus gnats and thrips in the grow medium.

Environmental Conditions:

• The minimum temperature for the successful use of Stratiolaelaps scimitus is 15°C/59°F.
• For optimal results the soil has to be moist, rich in organic matter and have a loose structure.

Note: Monitoring is essential. Inspect soil and Horiver sticky traps weekly to determine if additional releases are required.

Proper release techniques ensure the mites establish quickly and begin controlling pests effectively:

1. Gently rotate or shake the container before use.
2. Evenly distribute the carrier material directly onto the soil or growing media.
3. Focus applications around plant bases or areas with known pest activity
4. Do not release immediately before or after broad-spectrum pesticide applications. If pesticides are necessary, choose products compatible with beneficial mites.
5. Maintain proper growing conditions to maximize mite survival.

For best results, releases should be integrated into a broader IPM program that includes monitoring, sanitation, and complementary beneficials.