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Fall armyworms seem to be an increasingly difficult problem to deal with, and these destructive pests can wreak havoc on gardens and crops. For homesteaders and gardeners, keeping fall armyworms under control is crucial to preserving your flowers and vegetables.
Fall armyworms (Spodoptera frugiperda) are caterpillars that belong to the moth family. Native to the Americas, they are notorious for their rapid spread and ability to wreak havoc on a wide variety of crops. The adult moths lay eggs in clusters on various plants, and the emerging larvae, or armyworms, feed on the leaves.
The bad news is that fall armyworms are highly adaptable feeders and can consume over 80 different types of plants! They typically target plants in the grass family, including sweetcorn, maize, rice, and ornamental lawns. However, many gardeners report that fall armyworms will eat anything in their path.
Here’s how to get rid of fall armyworm effectively.
1. Hand-picking
Hand-picking is one of the simplest and most eco-friendly ways to control a small fall armyworm population. The best time to look for them is early in the morning or late in the evening, as they tend to hide during the heat of the day. Be sure to check the underside of leaves, where they often hide. Use gloves to pick off individual caterpillars and drop them into a bucket of soapy water.
2. Natural Predators
Create a biodiverse garden to attract natural predators such as parasitoid wasps, lacewings, ladybugs, ground beetles, and birds that prey on fall armyworm larvae and pupae.
Companion planting, wildlife ponds, birdhouses, and log piles are all great ways to attract natural predators to your garden. Consider leaving an undisturbed area of your garden to grow wildflowers, where beneficial insects can shelter and feed.
3. Neem oil
Neem oil is a natural insecticide derived from the seeds of the neem tree. It works by disrupting the hormonal system of pests, preventing them from feeding, reproducing, and molting.
Apply neem oil as a foliar spray to plants affected by fall armyworms, ensuring you cover both sides of the leaves. Reapply every 7-10 days, particularly after rain. When applied correctly, this oil is safe for humans, pets, and beneficial insects but should be avoided when bees are active.
4. Bacillus thuringiensis
Bacillus thuringiensis is a naturally occurring soil bacterium that targets caterpillars, including fall armyworms. When ingested, it produces toxins that damage the gut lining, causing the larvae to stop eating and die within a few days.
This fall armyworm treatment is most effective on younger larvae, so early detection is key. Apply Bacillus thuringiensis to the tops and undersides of leaves in the late afternoon or evening when larvae are active. It degrades quickly in sunlight, so reapplication may be necessary, especially after rain.
5. Spinosad
Spinosad is another biological pesticide, produced by fermentation of a naturally occurring bacterium. It affects the nervous system of the larvae, causing paralysis and death within 1-2 days.
Spinosad is used as a foliar spray and is best applied in the evening when fall armyworms are feeding. It is safe for most beneficial insects but can be harmful to pollinators if applied during the day.
6. Insecticidal soaps
Insecticidal soaps are made from potassium salts of fatty acids. They break down the outer membrane of soft-bodied insects like fall armyworms, causing them to dehydrate and die.
Insecticidal soap must come into direct contact with the larvae to be effective, so make sure to thoroughly cover the plants with this foliar spray. Insecticidal soaps are non-toxic to humans, pets, and most beneficial insects, making them a safe option for organic gardeners. However, avoid applying during the hottest part of the day, as it can burn the plants.
7. Diatomaceous earth
Diatomaceous earth is a fine powder that cuts through the exoskeletons of insects, causing them to dehydrate and die. It is a cost-effective way to deal with a fall armyworm infestation, performing as well as conventional insecticides in controlled studies.
Apply DE around the base of your plants or directly on areas where armyworms are feeding. It is most effective when dry, so reapply after rain or watering.
8. Row Covers
Row covers create a physical barrier, preventing fall armyworm moths from laying eggs on your plants. These covers are particularly useful for early crops and young seedlings, as they protect vulnerable plants from the beginning of the growing season. Remove the covers once plants start to flower to allow pollinators access.
9. Crop Rotation and Tilling
Fall armyworms can overwinter in the soil in the right conditions, so tilling your garden after harvest helps expose them to predators and cold weather. This disrupts their life cycle and reduces the number of larvae in the following season. Additionally, switching to crops they find less attractive can break the infestation cycle.
10. Essential Oils
Peppermint, clove, and rosemary essential oils can act as natural repellents against fall armyworms. Make a spray by mixing 10-15 drops of essential oil with water and a few drops of dish soap. Spray the solution directly onto affected plants and reapply every few days or after rain.
How to Spot Fall Armyworms
Fall armyworms are most prevalent during late summer and early fall, though they can appear year-round in warmer climates. They thrive in warm, humid conditions, which allows them to spread rapidly.
The first sign of fall armyworms is ragged or skeletonized leaves. These caterpillars grow quickly and need a voracious appetite to maintain this growth rate! To spot them before the damage is done, it pays to inspect your plants closely at dawn and dusk, when they are most active.
The fall armyworm moth lays clusters of tiny, round eggs on the underside of leaves, especially on grasses or crops. These can be hard to identify, and unless you are certain, any eggs should be left until they hatch.
Fall armyworm larvae are green-brown in color with distinctive white stripes along their sides. They grow rapidly over 2-4 weeks to about 1.5 inches in length. Once they reach full size, fall armyworm caterpillars pupate underground before emerging as adult moths.
