Sciarid flies

Introduction

Sciarid flies (Sciaridae) are a difficult pest, especially in young plant material. They can cause damage to seedlings, rootstock and cuttings of many plant species. In the cultivation of mushrooms they can be very annoying as well and cause both direct and indirect damage. Sciarid flies are often found in moist, organic environments.

 

Biology

Sciarid flies go through seven stages, namely egg, four larval stages, pupa and adult fly. Adults are noticed when they appear in large numbers. Eggs are deposited in the soil. Larvae generally eat rotting plant material, algae and fungi that are present in or on the soil. Pupation takes place in the soil as well.

 

Damage symptoms

• Direct damage can occur to young and/or weak plants in a moist, organic environment, when larvae chew the plant's roots. This reduces the uptake of water and nutrients, causing the plants to die. Strong plants are only affected at very high level of infection.
• Indirect damage is caused when larvae transmit mites, nematodes, viruses and fungal spores. Also adult sciarid flies can transmit various fungal spores. The places where larvae have chewn are also potential places where fungi can attack. All things together can be lethal to the plant.