Fungus gnat (Bradysia impatiens)

Size:

• Adult animals: 2 to 4 mm
• Larvae: up to 6 mm

Look:

• Black to dark grey colored, slender body
• Elongated, transparent wings with dark veining
• Long, thread-like antennae
• Larvae are glassy-white with a striking black head capsule spot.
• Possible confusion with other Bradysia species or Sciara

Way of life:

• It thrives in moist, organic substrates.
• Spread through contaminated soil, water and plant material
• Larvae live and feed in the substrate; adult animals fly near the plants.
• Prefer conditions with high humidity and temperatures above 18 degrees

Reproduction:

• Egg laying directly in the substrate
• The female lays 100 to 200 eggs in moist soil.
• Development from egg to fly takes place within 10 to 25 days.
• Several generations per month are possible under greenhouse conditions.

Infestation sites:

• Potted plants with peat-based or humus-rich substrate
• Seed trays, germination stations, young plant facilities
• Hydroponics, irrigation systems, substrate depots
• Compost mixtures or poorly stored potting soil

Nutrition:

• Larvae feed on dead organic material.
• In cases of high infestation pressure, feeding may also occur on living roots and seedlings.
• Promotes root rot and fungal infections (e.g., by Pythium or Fusarium)
• Adult animals do not ingest food

Behave:

• Flies fly out of the pots when disturbed and gather on windows and lights.
• They are often found on substrate surfaces or on the underside of leaves.
• Visible especially after watering or in damp rooms
• Strong attraction due to light, heat and moisture

Economic damage:

• Visible swarms of mosquitoes appear unhygienic.
• Disturbance in sales areas, waiting rooms, offices or patient rooms
• Loss of revenue in production and plant sales

Plant damage:

• Destruction of root tips, slowing of growth
• Wilting, young plants falling over
• Increased susceptibility to soil-borne fungal diseases

Mass reproduction:

• Explosive development occurs with overwatering and organic substrate.
• Reinfestation through new plantings, contaminated shipments
• Visible swarming in enclosed spaces; increased susceptibility to soil-borne fungal diseases

Disease transmission:

• Spread of microorganisms

Cultural measures:

• Consistently avoid waterlogging
• Cover surfaces with quartz sand or vermiculite
• Treat the soil thermally during propagation
• Store the substrate in a dry place and do not leave it uncovered.

Monitoring:

• Set up yellow sticky traps for early detection
• Control soil moisture and humidity
• Visual inspection when watering and moving the plants

Behave:

• Adjust watering cycles, especially with low evaporation.
• Check new plants and soil before planting.
• Empty waste containers with plant debris daily