kålflugor

Kålflugor, scientifically known as Delia radicum, are small, gray flies that are a common pest of cruciferous vegetables. The adult flies are about the size of a housefly but are more slender. They lay their eggs in the soil around the base of host plants, which include cabbage, broccoli, cauliflower, Brussels sprouts, kale, radishes, and turnips.

The larvae, or maggots, are the damaging stage. They are white, legless, and burrow into the roots and stems of young plants. This tunneling can stunt growth, cause wilting, and make the plants susceptible to diseases. In severe infestations, the roots can be completely destroyed, leading to plant death. The damage is often most noticeable in young seedlings or transplanted crops.

Kålflugor typically have two to three generations per year. The first generation emerges in the spring, laying eggs that hatch into larvae feeding on emerging crops. Subsequent generations continue to attack crops throughout the summer and into the fall. Adults feed on nectar and pollen, but it is the larval feeding that causes economic damage.

Control methods include crop rotation, as moving susceptible crops to a new area each year can disrupt the life cycle. Row covers can also be used to physically prevent adult flies from laying eggs on plants. Biological controls, such as beneficial nematodes that parasitize the larvae, can be employed. Insecticides are also available, but their use should be considered as part of an integrated pest management strategy. Early detection of the small, white maggots is crucial for effective management.