Fall Armyworm

Spodoptera frugiperda

Fall Armyworm, Armyworm, Buckworm, Budworm, Corn Budworm, Corn Leafworm, cotton leaf worm, daggy's corn worm, Grass Caterpillar, Grass Worm, Maize Budworm, Overflow Worm, Rice Caterpillar, Southern Armyworm, Southern Grassworm, Wheat Cutworm, Whorlworm, Alfalfa Worm

by mariconstantia (All rights reserved)
1 of 4
A close up image of a Spodoptera frugiperda fall armyworm moth on some white cloth
by mariconstantia (All rights reserved)
1 of 4
Spodoptera frugiperda is a species of moth that's a significant agricultural pest, and it's frequently sighted in gardens, too. Depending on the conditions, they can cause minor to severe damage. For example, with an abundance of appropriate plant types, the caterpillar larvae can obliterate the plants that lie in their path. Sometimes, when there are too many caterpillars versus food, they march in large groups to find areas of land with more food. This is where they get the common name 'Army Worm'. They favour any plant within the Poaceae family, as well as any other wild or cultivated grass species such as maize, rice, sorghum and sugarcane. They'll also attack other economically important crops, such as vegetables and cotton.
Free download for your phone or tablet
Download on the App StoreGet it on Google Play

Traits

These caterpillars are known to attack approximately 350 plant species.
A plentiful food for birds, bats and reptiles!

Appearance

Adult: There is a slight difference between male (wingspan: 3.7cm) and female moths (wingspan: 3.8 cm). Both are brindled with grey, browns and cream, but the female morph wing patterning is much less defined, possessing bigger patches of strips of cream and white, when compared to the male which appears to have more brown colouring. Larvae: The caterpillars can grow to a whopping 4.5cm in length! They possess three pairs of legs near the head and then four pairs of legs in the middle part of the body, with an additional pair near the rear. When they first hatch, they appear green with black lines and spots. As they grow bigger, they can take on three different colour morphs: green, light brown and black (gregarious form). They display a series of yellow-cream longitudinal stripes and black dots on the back. The defining feature of this species is the Y or V-shaped mark on the head. Eggs: The eggs are tiny but laid in clusters of up to 200! They're creamy-yellow and sometimes covered in jelly and hair (which is insect scales). They're typically laid on the surfaces of leaves.

Symptoms

Gross feeding damage to the foliage of grasses. Brown patches of grass are possible in lawns. Heavier infestations can totally defoliate crops such as maize, rice and other various cereal crops. Larvae feed on the seeds in whorls. It's often the reproductive structures that are targeted in plants. The whorl of plants may be covered in frass (insect excrement), holes and torn edges. Small larvae will skeletonise leaves. Numerous larvae are typically seen infesting the one plant, but they eventually move onto the neighbouring plants when the plant is depleted. Insect excrement can either be like 'saw-dust' or in larger lumps. When the number of caterpillars reach a certain number, they begin to disperse in large swarms, which is where they get the name 'armyworm'.

Activity

Nocturnal

Personality

Order

Lepidoptera

Family

Noctuidae

Metamorphosis

Complete

Distribution

Present throughout Africa, Asia, South and North America.

Biological treatment

These caterpillars have plenty of natural enemies that can keep them at bay. These include spiders, frogs, parasitic wasps and flies, small mammals and rodents, and birds. The damage they do to gardens is mostly aesthetic, but they can sometimes devastate smallholder farms. This is because they can sometimes be found eating in high densities, and it's at these times they can become severe. Pheromone traps can be purchased online. They trap the male moths; not only does it monitor an infestation, but it also makes it harder for a female to find a mate! If you see any beneficial lady beetles in the garden, you can relocate them to your lawn. They make short work of armyworm eggs, with the lacewings and minute pirate bugs. You can attract birds using elevated posts, seed and baths. Diatomaceous Earth can be purchased online; it has an unselective mode of action; however, it is an effective barrier against many pest insects. If available, beneficial nematodes can be purchased online and watered into your lawns. They will remove all of the eggs, larvae and caterpillars in your soil. Make sure you are buying the correct species suitable for eliminating the species at hand, or else they may not work. Its thought that neem oil can deter these caterpillars; however, when applying to lawns, this may not be the most eco-friendly way to go about removing these critters. It might be best to hold off using neem until later in the warm season when other techniques have become exhausted!

Chemical treatment

Persistent products include synthetic insecticides with a contact mode of action (e.g. cypermethrin, phenothrin, lambda-cyhalothrin and deltamethrin). These can still be toxic to some wildlife and a pollutant to water bodies, so please take care to research products and read instructions carefully before using them. Likewise, if you intend to eat your crop, be sure to follow any instructions precisely and that the plant is listed on the product label. Please see our ‘Biological Treatments’ for alternative solutions to plant problems.

Attracts

These worms are attracted to various grasses in the Poaceae family.
Free download for your phone or tablet
Download on the App StoreGet it on Google Play

Plant Knowledge

Search our ever-growing knowledge base to find plants and information. Find out about pests and diseases you should be keeping an eye out for. Watch How to videos or follow step by step guides for tasks in the garden. Free download for your phone or tablet.
Download on the App StoreGet it on Google Play