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If you spot some iridescent green insects feeding on your garden plants, you might’ve discovered a Japanese beetle. This is a fairly dangerous pest because the insect has an extremely varied diet and can decimate a large part of your beautiful yard. Japanese beetles often feed on roses, but will happily munch on various plant leaves and ruin flowers or fruit crops. If you live in the Eastern and Midwestern parts of the US, it’s safe to say that your garden is vulnerable to the threat of Japanese beetles.
As the name of the insect suggests, this species was originally isolated to the islands of Japan. It has been introduced accidentally in the US at the beginning of the 20th century. The beetles arrived as grubs in soil on imported Japanese plants. Although a law attempted to prevent the introduction, it was too late. Japanese beetles were spotted in a nursery in New Jersey and they soon became widespread thanks to the lack of natural predators.
In this article, we’ll explore the best ways to get rid of pesky Japanese beetles ruining your plants. The first step is to confirm that you’re actually dealing with this pest specifically to ensure that removal methods will work efficiently.
Japanese Beetle Identification
Adult Japanese beetles feature distinctive copper-colored backs with an iridescent green visual effect. The blue-green head of the insect has a slight metallic tinge. Other helpful features that confirm the presence of the pest include the tan wings and white hairs in the abdomen area. Before becoming adults, the beetles remain in the soil where they can cause damage to the roots of various plants.
Although Japanese beetles have a fairly short lifespan, their high appetite makes them a serious threat to your garden. They tend to feed in small groups but can quickly destroy several plants during their lifecycle. Even if you only find a single Japanese beetle in your yard, it’s safe to say that you will find more after some time.
Signs of Japanese Beetle Damage
As opposed to other garden pests, Japanese beetles are not very discriminating when it comes to the plants they feed on. The insects enjoy eating all parts of the plant, especially the leaves and fruits. Despite not being picky, the beetles have certain preferences and tend to attack fruit-producing plants before anything else. They’re also attracted to roses and can even be found feeding on trees.
A notable sign of damage is the appearance of “skeletonized” leaves and flowers. Due to the fact that Japanese beetles focus on the delicious leaf tissue between the veins, plants start to look “skeletonized”. By itself, this damaging sign isn’t enough proof to confirm the identity of the pest because other beetles can also create this kind of damage. Look closely around the plant to spot the culprit as Japanese beetles won’t be far from their food sources.
Aside from the unsightly appearance of the leaves, Japanese beetles can also cause damage in other visible ways. If you spot brown patches on your lawn, it’s possible that grubs are attacking the roots of grasses. Plants in your yard that seem to be dying may have weakened roots due to damage from Japanese beetle grubs.
Ways to Remove Japanese Beetles
Whether you just spotted a few random Japanese beetles here and there or you’re facing a large infestation, there are multiple ways to control Japanese beetles. We’ll take a look at all the methods to restore the health of your garden starting from the mildest to the strongest control solutions. It turns out that just good horticultural practices can sometimes solve your Japanese beetle problem. Oftentimes, however, more direct pest killing is required.
1. Pick Them by Hand
Whereas other insect pests are small or hard to find, Japanese beetles are fairly large and can be picked by hand with minimal effort. It may sound like a time-consuming method, but picking the bugs by hand can be an effective solution to get rid of them. Japanese beetles don’t bite and move slow enough to catch them easily. Get a pair of gardening gloves and start grabbing every beetle you spot feeding on your plants. Put them in a container filled with water and soap to eliminate them quickly.
2. Set a Trap
If you’re worried about a Japanese beetle infestation getting out of control, setting a trap represents a great way to encourage the pests to move away from the plants. Try this great Japanese beetle trap on Amazon that’s specifically designed for this pest. It attracts male beetles before they can reproduce. The secret lies in the use of a pheromone or another type of attractant that will trap the insects in a special container that doesn’t allow for escape.
3. Try Row Covers
Knowing when Japanese beetles have peak feeding periods can be highly advantageous if you’re trying to get rid of them. You can create a reliable protective barrier for your plants with the help of row covers. Focus on the insect’s feeding period which usually starts in late May or mid-June, depending on the region. Row covers can be effective at controlling Japanese beetles, but they will also keep out pollinators which may not be good for some crops.
4. Get More Resistant Plants
Habitat modification could be a great way to control a Japanese beetle infestation. Although the pest feeds on a great variety of plants, there are still many species that are simply avoided by the beetles. The most resistant flowers are coral bells, hostas, impatiens, and chrysanthemums. When it comes to shrubs and trees that can keep Japanese beetles at bay, we can count holly, boxwoods, and pine trees.
Geranium plants are not exactly resistant to Japanese beetles but they can paralyze the insect upon consuming its petals. It’s a natural deterrent against pests. Beetles won’t die but they’ll be incapacitated for hours and become vulnerable to predators. Having some geranium plants in your garden is highly recommended to fight against Japanese beetles.
As part of habitat modification, it’s also a good idea to avoid grouping certain plants that are deemed very attractive by the pest. Japanese beetles tend to prefer plants that are naturally higher in sugar content as well as those that release certain smells. Research has shown that plants like roses, cherries, raspberries, and grapes should never be grouped together due to being more at risk of damage by the beetles.
5. Bring a Natural Predator Into Your Garden
Even if you manage to deal with adult Japanese beetles, grubs can be more difficult to control because they live hidden in the soil. A great natural solution is to bring certain parasitic nematodes to your yard which will feed on Japanese beetle grubs. Keep in mind that you need to take a very targeted approach to ensure that you only bring the right type of nematodes that snack on insect pests. The best parasitic nematodes to try for this control method include Heterorhabditis and Steinernema.
6. Prune the Roses
Japanese beetles seem to be harder to get rid of when they attack rose gardens. If you have many beautiful rose bushes, it’s recommended to prune the buds to prevent any new damage from the pests. After the initial blooming period, prune the roses some more to stop the beetles in their tracks. You might also take this opportunity to remove any discovered pests by hand. Make use of mesh covering for rose bushes if you’re worried about further damage from the insects.
7. Apply a Soap-and-Water Solution
Before you visit a store to purchase specialized insecticide, consider trying out a DIY solution first. A simple mixture of water and dish soap could be more than enough to kill the pesky bugs. Japanese beetles will quickly suffocate when coming into contact with soapy water. Add a teaspoon of liquid dishwashing soap to a quart of water. Spray the resulting solution directly on the beetles found on damaged plants. Even if they don’t die right away, the beetles can be killed by predators on the ground.
8. Use Neem Oil
Neem oil is a powerful non-toxic insecticide that controls a wide range of insect pests. It’s very reliable against Japanese beetles as well. Thanks to relying on a natural pesticide from neem tree seeds, this special oil won’t be harmful to your plants like a chemical insecticide may be. Adult beetles ingest the oil particles and will also pass the substance to their eggs. Therefore, neem oil could be very effective when it comes to destroying a more serious Japanese beetle infestation.
Check out this powerful neem oil spray that’s ideal for organic gardens where you plan to use only natural insecticides. Apply the spray to the plants targeted by Japanese beetles. Although neem oil is pretty harmless, it’s worth mentioning that you should be careful with it near garden ponds. The product can potentially affect aquatic life. Keep in mind that neem oil has to be applied again after each time it rains to get some consistent pest-removal results.
9. Go for a Strong Insecticide
If you have an overwhelming Japanese beetle infestation, your best bet is to treat your garden with a potent insecticide. Go for a pyrethrin-based product that should provide great effectiveness but without worrying about the safety of your flowers, vegetables, or fruiting plants. Try this pyrethrin insect spray mix. Use this concentrate to create a powerful solution ready to spray on affected plants. The insecticide is also reliable against other pests such as aphids and webworms.
Killing adult Japanese beetles may sometimes not be enough to stomp out a very difficult pest infestation. It’s also required to remove the white grubs, especially if your lawn has been heavily affected by dead patches of grass. Consider using a specialized grub killer for lawns like this one. If you apply it correctly, you will be able to enjoy a grub-free lawn for months and avoid turf damage.
If you’ve tried all the ways to remove Japanese beetles from this list and your problem still persists, it’s likely a good time to call in professional exterminators. Some infestations can be extremely hard to control using DIY methods. This invasive pest is best removed through preventive measures and good general gardening practices. It can be said that being proactive will reduce the chances of any future infestation to enjoy a beetle-free landscape.