Onion
leaf miner

Acrolepiopsis assectella

The onion leaf miner is a gray-brown or light spotted moth with a wingspan of about 16 mm. It belongs to the butterflies. The moth shows its main flight activity in the first half of the night.
Its yellowish-white larvae are about 13 mm long and have a greenish-ochre head and black spots on the body.

Life cycle of the onion leaf miner

The onion leaf miner overwinters as a moth, rarely as a pupa. The flight of the first generation begins around mid-June. The moth lays its eggs (cream-colored, 0.5 mm long) on the leaves of the plant. The larvae hatch after a few days. The pupation of the second generation takes place from September to October in a cocoon on the leaves. There are usually two generations of onion leaf miners. In favorable weather conditions, the first generation flies as early as mid-April, and the second generation flies from about mid-August. In this case, the occurrence of three generations is also possible.

Damage caused by onion leaf miners

The larvae of the onion leaf miner can cause considerable damage. The main damage is caused by the second generation that appears in August. Initially, a superficial scraping feeding can be observed, later the larvae feed their way to the heart of the plant in mine tunnels. Elongated mining and window feeding on leek and onion leaves results in death of the heart leaves. Decaying bacteria can enter the feeding tunnels and increase the damage. The adult onion leaf miner does not cause damage.

What plants are onion leaf miners found on?

Onion leaf miners infest leeks, leeks, onions, and chives.

Control leek moths with beneficial nematodes

Nematodes are tiny, filamentous soil organisms about 0.6 mm long. They are natural enemies of the onion leaf miner. Certain nematode species specialize in the onion leaf miner, among others, and can use its larvae for their own feeding and reproduction. The nematodes are supplied alive in a powder. For application, they should be mixed with water exactly according to package directions and applied to the affected areas.

What stages of the onion leaf miner can I control?

From June to September, the larvae of the different generations present in the soil can be controlled with nematodes.