Variegated Cutworm

Peridroma saucia

Variegated Cutworm

Peridroma saucia FvL by Fvlamoen (CC BY-SA 3.0)
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A close up image of a variegated cutworm Peridroma saucia moth against a white background
Peridroma saucia FvL by Fvlamoen (CC BY-SA 3.0)
1 of 10
The Variegated Cutworm is a renowned garden pest and not at all fussy with what it eats. The caterpillars of this moth will feed on a whole range of plants, most of which are common things grown in the garden, greenhouse and allotment. They're a nuisance pest with a track record of breaking into greenhouses, devouring most of the grown contents. Likewise, they show similar behaviours to the 'Fall Armyworm'. They march in large groups through agricultural fields, devouring crops as they go. They are most active once the sunsets, with caterpillars emerging from beneath the topsoil.

Traits

Has lots of natural enemies to keep them under control.
Has a varied diet of garden fruits and vegetables.

Appearance

Adults: Variable. Generally a dirty or ashy light brown with some mottling. The forewing have faded creamy-yellow circular marks and faint dark smudges; the wing margins have 7 dark brown dashes. The wingspans are 4-5cm (2 inches). Larvae: They possess 'greasy' or shiny looking skin. The heads are generally dark shiny brown. They can be distinguished from other cutworms using the 4 pale yellow dots on the back of segments. The rest of the body is mottled brown. There's a darkened 'W' mark on the last abdominal segment. Pupae: Normally between 1-3cm, are smooth and shiny and brownish-red in colour. Eggs: Laid in batches of roughly 60 eggs, which are grey-white in colour. They're found beneath the leaves of host plants.

Symptoms

Caterpillars eat foliage, buds and shoots. Seedlings and young plants may be cut at the base. Fruit may be tunnelled. Potato tubers are tunnelled by larvae.

Activity

Nocturnal

Personality

Order

Lepidoptera

Family

Noctuidae

Metamorphosis

Complete

Distribution

North and South America, Europe, Asia and Africa

Biological treatment

Unfortunately, some species of owlet moth give rise to caterpillars that can be highly destructive. Collectively known as Cutworms, these larvae can severely damage plants, particularly in agriculture. By regularly monitoring the high-risk plants in your garden (see below) you might be able to catch these pests before damage is made irreversible. If damage has already been done, not to worry, we've put together some tips and tricks that will help prevent another infestation in the following years. Always try to scarify and plough the soil before doing any planting. This will hopefully reveal any pupae or larvae hiding in the topsoil. Weeds and plant debris should be cleared two weeks to ten days before planting. Plant checks should be undertaken during the nighttime using a torch, or at dawn, this is when caterpillars will be most active. A range of insects and animals eat cutworms. Sometimes it's worth waiting for other insects to take care of your pests if the infestation is considered average. Parasitic wasps and flies use these caterpillars to feed their larvae. Likewise, ground beetles, lacewings, praying mantis, ants, and birds will all eat these insects. Before you sow your seeds, let your chickens loose on your veg patch. They will clear the area of grubs, caterpillars or any overwintering pupae. If available, you can purchase beneficial predatory nematodes from some commercial retailers. Watering these into the soil should eliminate the caterpillars hiding beneath the topsoil. Soil temperatures need to be between 12-20ºC for the treatment to be effective. Diluted neem seed and leaf sprayed onto potato in regular intervals is proposed an effective treatment. Baits are most effective when other resources are limited. These can be purchased online or from garden retailers. If available, pheromone traps are a brilliant way to catch male moths in search of females. Not only do you reduce the reproductive success of the males in the area, but you can also use traps to monitor the infestation level of your garden. Installing protective collars, made from plastic cups, bottles, or paper tubes, etc., can help protect the stems of young plants. Sticky substances are another barrier that can be effective at preventing caterpillars from reaching stems. Diatomite earth, sawdust, or crushed eggshells are substances disliked by caterpillars.

Chemical treatment

Lastly, there is a whole range of chemical products varying in persistence and toxicity, that can be purchased from a local garden centre. It's always best to check the products active components before using them. They're frequently undergoing restrictions and bans. Follow label instructions carefully and always double-check if you are feeling unsure. Be sure you're using the correct volumes of product to water ratio, using the proper nozzle. It's essential to assess whether the crop is worth saving or not because treatments can result in some resistance build-up in the pest population. Likewise, if you intend to eat your crop, be sure it's listed on the bottle label. Contact insecticides containing natural plant oils can be more environmentally benign than synthetic pesticides. Look out for products containing natural pyrethrums, fatty acids and plant oils. Synthetic pyrethroids that are available for home use include ingredients: Deltamethrin, lambda-cyhalothrin and cypermethrin.

Attracts

Repels

Many species of parasitic wasps and flies, spiders, birds and bats.

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