Carrot fly is a widespread problem, and gardeners and farmers have developed a range of techniques to deter them.

Companion planting. Completely encircling your carrot crop with allium family plants such as onions, leeks or chives is believed to literally throw carrot fly off the scent. As with most companion planting advice there is conflicting evidence on its effectiveness, so it’s worth experimenting in your own garden.

Strategic sowing times. Carrot flies are active from late spring until autumn. By delaying sowing until early summer, you can sidestep the first generation of the pest.

Avoid thinning. The process of thinning out carrots bruises the foliage and intensifies its scent, which is said to attract carrot flies from some distance away. Sow sparsely instead, so that thinning is not required.

Using seed tapes will eliminate the need for thinning.