|Protect your runners or French varieties against bean seed flies
Image: A.S. Floro
If you’re growing beans in your plot this year, watch out for bean seed fly. The maggots of these flies can damage - or even kill - your bean seedlings.
|Clear signs of damage can be seen from bean seed fly larvae
Image: Eric Burkness, Department of Entomology, University of Minnesota
Bean seed fly (Delia platura) look like small house flies (6mm long). Itâs their white, headless and legless larvae, however, that do all the damage.
Adults become active in the late spring, laying eggs in the soil. When their eggs hatch, the maggots (reaching up to 8mm in length) feed on bean seeds and roots - and cause severe damage to seedlings.
There can be up to five generations of bean seed fly during a year, but the first generation often does the most damage. That’s because beans sown in colder, wetter soils, take longer to germinate - giving the maggots more time to do harm.
|Plants affected by bean seed fly will be weak and lack vigour
Image: Potato Agronomy on Twitter
Here’s how to work out if bean seed fly are harming your crops:
|Bean seed flies can be controlled with specific gardening methods
Bean seed fly maggots feed on the seeds and roots of beans - especially French and runner beans. They sometimes also feed on brassicas, gourds, lettuce, onions and sunflowers.
There are several effective ways to control bean seed fly in your garden:
For more information on growing your own peas, head to our pea and bean hub page.