Dalotia coriaria — Rove Beetles for Fungus Gnat & Shore Fly Control
How to Say It: duh-LOH-shuh kor-ee-AIR-ee-uh
A fast-moving predator for the top layer of your soil.
Fungus gnats, shore flies and other soil pests spend most of their lives out of sight, as eggs and larvae in damp growing media. Dalotia coriaria, the rove beetle, hunts them right where they hide. This small soil predator does most of its work at night, moving quickly through the top layer of soil and feeding on several pest life stages, especially eggs. In moist greenhouse and propagation media, rove beetles can reproduce alongside the pests they hunt.
What Rove Beetles Are
Dalotia coriaria (formerly Atheta coriaria) is a generalist predator about 3–4mm long. Adults are brown-black and winged, with short wing covers that leave most of its slender abdomen exposed. When disturbed, it curls that abdomen upward, a habit shared by many rove beetles. The larvae are slender and pale yellow, turning darker as they mature. Both larvae and adults feed on pests, and eggs are their main prey. In the wild, rove beetles live in moist soil, leaf litter and decaying plant material. They are quick runners and capable fliers, which lets them cover a lot of ground while searching for prey.
Rove Beetle Pest Targets
Primary targets
- Fungus gnats (eggs and larvae)
- Shore flies (eggs and larvae)
- Moth flies (larvae)
- Thrips (pupae in the soil)
Secondary targets
- Springtails
- Root mealybugs
- Root aphids (some control)
How Rove Beetles Work
Both adults and larvae are predators, so a rove beetle population hunts at two life stages at once. Females lay their eggs in the growing medium near pest activity, and each new generation adds more hunters to the soil. It takes about 14-21 days for the full egg to adult cycle, with adults consuming pests for up to 60 days.
When to Use
Rove beetles work best as an early, preventive step. Add them at the start of propagation, before fungus gnat and shore fly numbers climb. The damp media used for cuttings and seedlings suits both the pests and the beetles. For an existing infestation, use the higher rate below and check pest numbers often. Plants moved to new containers or beds after an application need a fresh application in their new spot.
Application Rates
| Pest pressure | Rate |
| Light or preventive | 1 beetle per sq. ft. |
| Moderate | 2–4 beetles per sq. ft. |
| Heavy (hot spots) | 4–8 beetles per sq. ft., applied directly to problem areas |
These are general starting points — actual application should be adjusted based on pest pressure/species, plant type, and infestation severity.
Temperature & Humidity Range
Temperature: 55–90°F
Humidity: 50–80%
Moisture: rove beetles need consistently damp (not soggy) soil or growing medium to stay active.
Application Instructions
- Plan to apply in the early morning, the evening or another cool part of the day.
- Check that the soil or growing medium is slightly damp but not wet. Avoid watering for a few hours after applying.
- Before opening, gently roll the bottle back and forth so the beetles spread evenly through the bottle.
- Carry the closed bottle to the area you're treating. Rove beetles run fast, so open it only when you're in place.
- Sprinkle the contents evenly over the soil or growing medium of the affected plants or concentrating groups of 50-100 in hot spots.
- Skip broad-spectrum and systemic insecticides, which harm rove beetles at every life stage. Wetting agents like neem oil and insecticidal soap can also reduce results.
- Adjust how often you apply based on plant size and type, pest pressure, other beneficials present, and temperature.
Pairing for Layered Pest Control
For stubborn fungus gnat problems, combine rove beetles with Hypoaspis miles predatory mites and Sf beneficial nematodes. Each works a different part of the soil, so together they cover more pest life stages than any one alone.
Sustainable Pest Management
- Biological control that fits into Integrated Pest Management (IPM) programs
- Reaches pests in the soil, where foliar sprays don't go
- Suited to greenhouses, propagation areas and home gardens
Storage
Apply as soon as possible after your order arrives. If you need to hold it briefly:
- Keep at 45–55°F for no more than 48 hours.
- Do not refrigerate. Do not freeze.
FAQs
How many rove beetles do I need for fungus gnats?
For prevention or light pressure, start at 1 beetle per square foot. For moderate pressure, use 2–4 per square foot, and for heavy hot spots, 4–8 per square foot applied directly to the problem areas. Adjust based on pest numbers and plant type.
Can I use rove beetles with Hypoaspis and beneficial nematodes?
Yes. All three target fungus gnats in the soil, and using them together covers more pest life stages.
Can I spray insecticides while using rove beetles?
Avoid broad-spectrum and systemic insecticides, which harm rove beetles at every life stage. Wetting agents including neem oil or insecticidal soap could also create an adverse environment.
Do rove beetles work in dry soil?
No. They need consistently damp growing media, so keep soil moisture steady while they're working.
When is the best time to start?
Early, before pest numbers build. In greenhouses, the start of propagation is ideal.