Hoverflies (also called flower flies) earn their keep twice over — the adults pollinate your crops, and their larvae are aphid-eating machines. They look like small bees or wasps but can't sting, and they hover dead-still in the air, which gives them away.
What do they do?
Adults pollinate flowers as they feed on nectar. The larvae — small, legless maggots — hunt aphids, thrips, scale and small caterpillars.
How do I spot them?
- Black-and-yellow banded and bee-like, but with a single pair of wings and that giveaway hovering flight.
- They dart in, hang motionless mid-air, then zip off.
- Larvae are little green or cream maggots, usually right in an aphid colony.
How do I attract and keep them?
Adults feed on open, shallow flowers, so alyssum, marigold, dill and cosmos are magnets for them. Plant a variety of flowers among your veggies (see our companion planting guide), go easy on sprays that kill the good bugs along with the bad, and leave a shallow dish of water out in hot weather.
A garden that keeps hoverflies happy rarely has an aphid problem for long. For the full approach, see our guide to managing pests the safe way.
Image: TTaylor, CC BY 2.5, via Wikimedia Commons.