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Japanese beetles, scientifically known as Popillia japonica, are highly invasive pests that can cause significant damage to gardens and crops. They pose a significant problem because they feed on many plant species’ leaves, flowers, and fruit and harm lawns by feeding on grass roots.
While often mistaken for a ladybug, Japanese beetles have distinctive physical characteristics that make them easy to recognize. They are small, typically about 1/2 inch (12 mm) in length, with a shiny, metallic green oval body and coppery-brown wing covers. Their most prominent feature is small white tufts of hair along the sides and back of the abdomen.
Most damage caused by a Japanese beetle is easy to spot. There are distinct signs such as skeletonized leaves, flowers with chewed, ragged petals, and fruits with holes or scarring. In lawns, brown or dead patches indicate Japanese beetles active from larvae feeding on grass roots.
If Japanese beetles are causing problems in your garden, consider trying one of these natural methods to eliminate them.
Handpicking
If small numbers of Japanese beetles are present, the quickest and most effective way to remove them is by picking each one off by hand and dropping them into a bucket of soapy water to kill them. The beetles appear from late spring onwards, so make a regular plant inspection part of your daily routine to stop this garden menace in its tracks.
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Neem Oil
Neem oil kills adult Japanese beetles, their larvae, and eggs. Use it as a targeted spray in problem areas where Japanese beetles have been seed-feeding. Avoid widespread spraying of neem oil, as it can also harm beneficial insects.
Garlic Spray
The smell of
Grow Resistant Plant Varieties
To reduce the amount of Japanese beetle control, you need to grow plants such as boxwood or holly that are less attractive to Japanese beetles.
Companion Planting
Some plant species, such as
Trap Crops
Certain plants, including borage, white geraniums, evening primroses, and zinnias, are highly attractive to Japanese beetles and will draw them in large numbers. Grow a patch of sacrificial plants to lure Japanese beetles away from other crops; the beetles can then be collected and killed.
Attract Natural Predators
Plant nectar-rich flowers to encourage beneficial insects like tachinid flies and parasitic wasps, which prey on Japanese beetles. Alyssum, cilantro,
Insecticidal Soap
Insecticidal soap only works on contact and has no residual activity, so it must be sprayed directly onto every Japanese beetle you spot. When used carefully, this method is non-toxic to other beneficial insects.
Attract Birds
Install birdhouses to attract birds such as robins and cardinals that feed on Japanese beetles. Robins prefer a secluded nesting area such as a dense hedge where they can raise their young without being disturbed.
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Prune Infested Branches
Damaged leaves give off chemical signals that attract even more Japanese beetles to your garden. Regularly inspect plants and crops and carefully prune away any damaged leaves or branches.
Row Covers
When the larvae turn into adult Japanese beetles, they quickly fly to their preferred feeding sites. To minimize damage, protect vegetable crops with horticultural fleece or fine mesh row covers.
Kaolin Clay
Kaolin clay forms a thin barrier that prevents Japanese beetles from feeding on leaves. This is available in a spray that is simple to apply and gives instant results when used in areas prone to Japanese beetle infestations.
Essential Oils
Essential oils like peppermint, wintergreen, or
Watering Control
Japanese beetle grubs thrive in moist soil. Reducing moisture levels can help limit their development. To reduce Japanese beetle populations, switch to drought-tolerant plants and grasses and keep watering to a minimum.
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Milky Spore Powder
Milky spore powder contains bacterial spores (Paenibacillus popilliae) that infect Japanese beetles without harming other insects. Apply milky spore powder to your lawn to target Japanese beetle grubs during high-risk periods.
Beneficial Nematodes
Tiny microscopic worms called nematodes will infect and kill Japanese beetle larvae in the soil. Make sure to only purchase nematodes that specifically target Japanese beetles, as many types are available.
Row Covers
When the larvae turn into adult Japanese beetles, they quickly fly onto their preferred feeding sites. To minimize damage, protect vegetable crops with horticultural fleece or fine mesh row covers.
Bacillus thuringiensis
Bacillus thuringiensis is a biological insecticide that targets Japanese beetle grubs in lawns and gardens. Although highly effective, certain strains of Bacillus thuringiensis have been shown to harm monarch butterfly populations and should not be used in gardens where these endangered insects are present.
Kate Chalmers
Kate is a passionate gardener who has a keen interest in all things related to homesteading and sustainability. She resides in Portugal with her husband and menagerie of animals and has over 15 years of experience in the UK veterinary industry. In 2020, Kate and her husband took on a dilapidated Portuguese house and abandoned olive grove, turning it into an abundant food forest and home for nature.
Life on the homestead is never the same from one day to the next, and Kate has mastered many skills that she is keen to pass on to anyone with an interest in becoming more self-sufficient. Kate believes that living a sustainable lifestyle is the key to happiness and fulfillment and that everyone can make simple changes that connect us back to nature and reduce our impact on the planet.
I very much appreciate the article on how to combat Japanese beetles. It is the most informative one I have read.
That’s so good to hear. So happy we can help.