Orchids infested with black flies

Clare Murphy asked 13 years ago

Within a few weeks of repotting my orchids (phalaenopsis) they were infested with small black flies. The flies are very small and seem to die off after a number of days.To try and control the pests I disposed of the ‘infested’ potting compost and repotted the orchids in a new compost. Before repotting I washed the leaves and roots with water. Unfortunately the flies came back after about two weeks and have multiplied rapidly.Can you suggest any insecticides that should be used? Should I repot the plants again but this time wash the plants with insecticide?

1 Answers

Gerry Daly Staff answered 3 years ago
It is likely that these are mushrooms flies. They are attracted to overly wet compost where they lays eggs and further generations emerge.

Simply reduce watering. Allow the comost to become slightly dry on top before watering. The flies that have appeared may have come from other pots that are similalry too wet.