Bean seed fly (Delia platura)
The bean seed fly, also known as seed corn maggot, resembles small houseflies. It is about 1cm long.
Female flies are attracted to recently disturbed open soil, where they lay eggs, especially where there are plant residues or when large amount of manure has been applied. The maggots bore into germinating bean seeds or the cotyledons (first seed leaves) of the young plant eating them. This causes patchy emergence of seedlings. If damaged plants emerge, they are stunted, weak and fail to develop into productive plants.
Pupation takes place in the soil, 2-4 cm under the soil surface.
- Limit the amount of organic matter before planting in areas with a known history of bean seed flies.
- Avoid sowing into recently ploughed land in areas where this fly is a problem.