Fight against the leaf miner

The leek leaf miner (Phytomyza or Napomyza gymnostoma) is a recently discovered pest! This dipteran was reported in 2003 in eastern France and is believed to have originated in Central Europe and the Balkans. The damage caused by the larvae is considerable and poses a problem for many farmers. Attacks can occur as early as spring and autumn and cause stunted growth, deformation, bursting of the stem, or even death of the plant. But the leaf miner doesn't only affect leeks! It also attacks other species belonging to the Alliaceae family, such as chives, garlic, and onions. What is the lifestyle of the leek leaf miner? The leek leaf miner is now a common pest in crops. The main damage is caused by the larvae and is often followed by infection by a fungus or bacteria that causes plant rot. The adult is a small grayish fly about 3mm long, with a yellow forehead and underside of the abdomen. The insect spends the winter as a reddish-brown pupa, attached to the tissues of the leek. Adults emerge at the end of winter. The female lands on the host plant and feeds by pumping the sap that emerges following her bites. Aligned punctuations making lines of white dots can be observed on the foliage. She lays her eggs during April in the tissues of the outer leaves and makes incisions in the axis of the foliage, depositing the eggs. The pale yellow larvae, about 6 cm long, then dig mines in the green part and in the stem, up to the base of the leek. They then transform into pupae and remain in their galleries until the end of summer. A second generation is formed in the fall and then the larva transforms into a pupa to spend the winter. How to control leek flies? As a preventative measure, carefully install an insect net in late winter and autumn when leek flies are in flight. These insects can lay their eggs through the net, so make sure the leaves do not come into contact with the net. Remove pupae and peelings. Pupae can survive in the compost, complete their development, and form a second generation. Protect winter leeks by storing them in the freezer. Stagger your sowing dates so that no host plants are present in the vegetable garden when the leek flies are in flight.