Leek moth, Acrolepiopsis assectella

Is an economically important pest of the crop plant under genus Allium.

The main host plants are leek and onion. This common pest is distributed throughout Europe from Austria, Belgium, Britain, Czechoslovakia, Denmark, France, Germany, Greece, Hungary, Italy, Netherlands, Norway, Poland, Spain, Sweden, Switzerland, Yugoslavia (CIE, 1980). It is also distributed in southern Scandinavia, extending across Russia to Siberia (Zhang, 1994). Leek moth is also reported as an economic insect in Algeria (Lecomte, 1976) and Japan.


Females lay about 100 eggs, each alone at the base of the host plant. The eggs hatch in 5 to 8 days. Larval development involves five instars and takes 15 days at 25°C.

The larvae are 10 -12 mm in length. The larvae pupate in an open-network cocoon on dead vegetation. Pupal duration is 10 days at 25°C (INRA, 2000).

The adult moths are 16 to 18 mm in wingspan (INRA, 2000) (15 mm in wingspan according to Carter, 1984). The head and thorax are dark brown; the abdomen, greyish brown. The antennae are simple and filiform (Carter, 1984). The moths of the second generation hibernate in plant debris (Carter, 1984; INRA, 2000). Influenced by temperature, the adults resume dusk and night flights in March or April (INRA, 2000).

The females fly at night in an irregular zigzag pattern. Copulation occurs in the early morning and lasts for several hours.

Nature of Damage

In Europe, the leek moth causes heavy damage to leeks, onions, and related crops by mining and feeding within the foliage and bulbs. Damage is followed by extensive rotting.

The larvae also feed on the seed stalk preventing the formation of the seed (USDAARS, 1960). Larvae mine and bore through the folded leaves of leeks, producing a ‘shot-hole’ effect. They also feed inside the hollow leaves of onions and sometimes bore down into the bulb.

When flowering shoots are attacked, severe losses of seed may result. This is a serious pest in continental Europe, particularly in France and Belgium. Attacks in the British Isles are sporadic (Carter, 1984).


Russell IPM manufactures and supplies pheromone lure – the Qlure, traps and complete monitoring systems for Leek moth, Acrolepiopsis assectella, also known as onion moth.

Pheromone trap data gives early warning of the infestation and will also alert the user to a low level of population before it becomes serious.

The lure can be best applied with the Mothcatcher trap or Delta trap.

Application Guidelines

Lures can be changed every 4-6 weeks to get the most accurate results.

Lures Handling
Pheromone lures are a very sensitive tool. They can be affected by exposure to elevated heat and direct sunshine. Direct touching by hand may cause cross contamination leading to mixed catches in the trap. Some contaminants such as Nicotine May have repellent effect reducing trap catch.

Lure Storage
Store in a cool dry place. Shelf life can vary from 3-36 months depending on the storage temperature. See Technical Data Sheet for further details.

Trap Selection

The Deltra trap is the most sensitive trap to use for monitoring this insect. However, Moth catcher may be used in dusty conditions or in high moth population density.

Trap Density

Do not re-use the trap to monitor different insects as this may lead to mixed catches. One trap for every two hectares of large scale fields of homogenous lands.

Two traps per hectare (2trap/ha) for small holdings and in field of uneven topography.

Trap Position

Place traps near the highest point of the plant using supporting posts approximately 1 meter high, or higher if the crop is higher.

Data and Interpretation

Collect data weekly from the start of the flight of the over wintering generation. During the height of the population more frequent reading may be needed. Decisions on pesticide application should not be taken solely on the trap catch data. Climatic and biological considerations should be taken in account.

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