Cabbage Moth

Mamestra brassicae

Cabbage Moth

Mamestra.brassicae.7460 by Olaf Leillinger (CC BY-SA 2.5)
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A birds eye view of a Mamestra brassicae cabbage moth on a wall
Mamestra.brassicae.7460 by Olaf Leillinger (CC BY-SA 2.5)
1 of 4
The Cabbage Moth is a variable moth, so it can be difficult to identify in the garden or allotment. Generally, wing colouring is mostly greyish-brown, providing perfect camouflage when resting on tree bark and the soil. The severity of damage can vary year to year. They favour Brassicas but they've also been found on Lettuce, Chicory, Spinach, Tobacco, Beets, Onion and Beans. Caterpillars will begin to feed on the outermost leaves of the vegetable, leaving irregular holes and tears in their paths. They then move on to boring within the hearts of vegetables.

Traits

Caterpillars bore into the fruits and vegetables, causing rotting.
These moths are eaten by an array of wildlife.

Appearance

Adults: moths wings are speckled with grey, brown and green, but patterning can vary between individuals. Wingspan range is 3-4.5cm. Larvae: Can reach 4cm. They are greyish-brown and green, but colouration can vary. They sometimes possess a stripe running laterally down the body. Faint banding can be evident on each segment on older caterpillars. Pupae: The pupa, or cocoon, is a dark tan colour that with a slight sheen to it. Eggs: Eggs are laid in clusters of 50-60 and are pale green.

Symptoms

Small holes in the outer surfaces of the vegetables. Entry holes leading into the core. Skelotonised leaves Vegetables may begin to rot Brown frass (insect excrement!) on plants Larvae will also attack inflorescence. Larvae bore into seeds or pods (if any) Damage to buds, leaves and petals.

Activity

Nocturnal

Personality

Order

Lepidoptera

Family

Noctuidae

Metamorphosis

Complete

Distribution

Europe, America, Northern Africa, and parts of Asia

Biological treatment

By checking your vegetables regularly, you should be able to detect any caterpillars before they cause much damage. Cabbages can be covered with netting to prevent eggs from being laid on the plants. Carefully ploughing the soil following a harvest is a good way to sort out and remove overwintering pupae. Vegetables sown earlier in the year tend to be affected less by these caterpillars.

Chemical treatment

Insecticides such as deltamethrin, cypermethrin, malathion and fenitrothion can be used. On plants intended for eating, be sure the crop is listed on the pesticide label and follow the instructions carefully. If you decide to use persistent chemicals please research products carefully, or consult with your local garden centre. Plants in flower should never be sprayed, as these chemicals can be detrimental to pollinators.

Attracts

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