Carrot Rust Flies

Identification

Adult carrot rust flies are very small, shiny black flies with an orange head and legs. The larvae are tiny, beige-colored maggots. Though this pest is not found in every guide to vegetable garden pests, it’s becoming more problematic for many gardeners and deserves to be featured.

Damage

Carrot rust fly larvae feed on crop roots, leaving tunnels and scarring behind. As the season progresses, the damage grows more prominent. Roots riddled with tunnels and scars are the result.

Prevention

Adult carrot rust flies are poor fliers so rotate crops every season. Try to pick a site downwind from last year’s crop location. Also, wait to plant carrots until late May or early June as that’s off the mating cycle of this pest.

Physical control

Keep carrots and other susceptible crops covered with floating row cover from the time of planting until harvesting day. Female flies find their host plants through smell, so inter-planting carrots and other crops with onions, garlic, and chives may help limit carrot rust fly egg laying.

Chemical control

Beneficial nematodes released into the soil near the carrot crop help control the larvae. Species of nematodes in the genus Steinernema are most effective. Apply in the spring according to the package instructions.