How To Get Rid Of Japanese Beetles In Garden

Dealing with Japanese beetle damage in your garden can be rough. Therefore, prevention is better than cure. One way to prevent Japanese beetles is to avoid overwatering.

Overwatering can dampen the soil excessively, creating a conducive environment for the grubs to grow and thrive. They live close to the soil's surface and feed on grass roots. Therefore, you should water on when needed. Usually, young plants need deep watering regularly, but once established, they need much less.

Another preventative method is to grow susceptible plants with other beetle-resistant plants. Susceptible plants are those that Japanese beetles love to feast on, like roses, grapevines, hollyhocks, beans, hibiscus, sunflowers, dahlia, and many more.

Gardeners are often tempted to plant similar, attractive plants together to beautify their gardens. But this only creates a buffet of favorite food for the beetles. It is better to surround your favorite susceptible plants with Japanese beetle-resistant varieties like lilacs, viburnums, or catnip.

This creates a barrier of entry for the beetles. Also, avoid planting your favorite susceptible plants in clusters. For instance, if you love sunflowers, spread them around the garden and mix them with other beetle-resistant plants.

Plant care consists of regular inspection, not just watering, pruning, or fertilizing. Regularly checking your plants and being on the lookout for these beetles allows you to take action before they cause significant damage.

You should inspect your plants at least once a week from mid-June to late August when Japanese beetles thrive. Focus on areas the insects feed on, such as the leaves and soil. You might find the beetle munching on the leaves or notice dead patches of grass or areas. 

Once you know your plants are infected, you can non-aggressive and more natural ways to help your plants. Insecticides should be your last resort, as they can kill other beneficial insects.

Once you know your plant is infested with Japanese beetles, you can handpick them off the plants. Handpicking is suitable when you have small gardens and do not want to use chemicals that could kill other beneficial insects like ladybugs.

It is especially effective when the beetle population is at manageable levels.  If you want to handpick them, do it early morning or late evening, when beetles are less active, making them easier to catch. Do not squish them in your hands as they release pheromones that attract more beetles.

Another gentle and natural way to remove Japanese beetles is to spray neem oil on infected areas. Neem oils contain potassium bicarbonate that prevents the beetles from feeding and mating.

When the adult beetles ingest a chemical in the neem oil, it passes on in the eggs, and the resulting larvae die before becoming an adult. For application, mix neem oil concentrate with water according to the product label instructions. Spray the mixture thoroughly for 7-10 days on the stems and the leaves, especially the undersides, where beetles like to hide.

You need to rely on milky spores to kill off the grubs. Milky spore is a soil-dwelling, Gram-positive, rod-shaped bacterium that targets and kills Japanese beetle grubs. They do not harm adult beetles but infect and kill their grubs that live underground and feast on grass roots.

When grubs ingest the spores, the bacteria multiply within them, leading to their death. These spores remain dormant in the soil for decades, continuously killing grubs as they hatch from new eggs laid by adult beetles. Moreover, these spores are safe for humans and pets and are environmentally friendly, unlike some insecticides

Beneficial Nematodes are microscopic roundworms that occur naturally in soil. These roundworms prey on many pests like grubs, caterpillars, thrips, wireworms, leatherjackets, fungus gnats, crane flies, and more.

Upon locating a grub, the nematodes penetrate its body through natural openings and release bacteria that kill the grub from the inside out. The nematodes reproduce within the deceased grub, generating more nematodes to continue hunting for additional grubs.

Nematodes are available in garden centers and usually come in powdery clay that must be mixed with filtered water. You can follow the package instructions. Once the nematodes dissolve in water, fill them in a spray can and spray the solution across the area you want to treat.

Garlic spray is a popular home remedy to control Japanese beetle populations. Garlic contains sulfur compounds, like allicin, that cause a pungent odor. Japanese beetles cannot stand the smell and avoid plants with garlic spray.

To make the garlic spray, blend chopped garlic cloves with 1 cup of water until you have a smooth, liquid mixture. After that, strain the blended liquid through a fine-mesh strainer to remove solid garlic pieces.

Then, pour it into a spray bottle with soap and use it on the leaves of your plants. Ensure you test it on a leaf before using it on the entire plant. Frequent reapplication is necessary as its repellent effect is temporary.

Row covers are synthetic fabrics placed directly over your plants to protect them from cold temperatures, harsh sunlight, and pests like the Japanese beetle.

They create a physical barrier that prevents the beetles from landing on and feeding on the leaves. When the beetles cannot reach the plants, they will not be able to skeletonize the leaves and damage the plants. However, the downside to using a row cover is that it can ruin the visual aesthetics of your garden.

If you still want to use row covers, choose one tall enough to cover your mature plants. Although row covers are made from breathable fabric, they may still limit ventilation on hot days. To combat this, you can clip up the sides of the row cover. 

Trap crops are like sacrificial lamb. They lure beetles away from your garden, making them easier to control. Planting Japanese beetle traps involves planting crops that the beetles love, like roses, raspberries, grapes, and hollyhocks.

Roses are beetles’ favorite food, and with roses around, beetles are less likely to feast on your other fruits and vegetable crops. Remember placement is crucial if you want to plant these Japanese beetle traps. Plant your trap crop away from your valuable plants. The further away, the better the distraction. Your trap crop will be damaged but that is the intended purpose. 

Apart from using crops as a Japanese beetle trap, you can buy commercial devices that trap adult beetles. One such device is the beetle bag trap. The bags are hung on trees and are green in color. The vibrant color lures the beetles, and once they enter the trap bag, they cannot leave.

Another device is the beetle bait trap. These traps look like buckets with lids and are filled with bait. Ensure the bait is fresh, and add water if needed. Once the beetle enters the trap, it drowns in the liquid.
 
Place the traps away from the plants you want to protect. The further away, the better. Remember to empty the traps regularly, as they can get full quickly. These devices need to be replaced every few weeks.

The fastest way to get rid of Japanese beetles is to use pyrethrin-based insecticides. These insecticides are derived from the chrysanthemum flowers and can control various garden pests.

Once the pests come in contact with the poisonous chemicals in the insecticides, they are paralyzed and die. The poison must directly touch the insect to be effective. Although the insecticides can instantly kill the beetles and are fast-acting, their effects are short-lived.

It can break down quickly in sunlight and water. Therefore, reapplication may be necessary. However, it can also kill beneficial insects like bees and ladybugs, so use it wisely. The best time to use this spray is early morning or late evening when beetles are less active and cannot escape. 

Diatomaceous earth (DE) is a type of sand made from the fossilized remains of tiny aquatic organisms called diatoms. These diatoms have sharp edges that human eyes cannot see. But they certainly cut through the pests’ exoskeletons.

These cuts lead to dehydration and eventual death. For effectiveness, they must come in direct contact with the pests. You should wear a mask before applying the DE, as you can inhale it.

One of the simplest solutions is soap water spray. The soap breaks down the beetle's protective outer layer, leading to suffocation. Mix water with a few drops of dish soap and spray it directly on the beetles to kill them.

Use a mild dish soap as it is gentler on the plants. Harsh detergents can kill the plants and other beneficial insects. It is also difficult to rinse off plants and leaves residue, which can damage the plants.

This method is better with handpicking because if you spray the soap solution directly on the plant, you have to wash it off, which is time-consuming. The best time to spray this solution is early morning or late evening when beetles are less active.

Another way to get rid of the Japanese beetles is to attract natural predators. So, what eats Japanese beetles? There are many Japanese beetle predators like ladybugs, lacewings, ground beetles, and assassin Bugs.

If you want to rely on predators to remove the pesky beetles, you need to create a conducive environment where they can survive and grow. These beneficial insects cannot survive pesticides, so opt for organic or natural alternatives to increase their population.

Additionally, you should provide a suitable habitat with various plants, including native species. Do not overcrowd your garden and provide shelter for these insects. You can also plant flowers with pollen and nectar to attract these insects.

Taking care of the garden properly can also prevent Japanese beetles. There are several strategies to achieve this. Select plants less appealing to Japanese beetles, such as garlic and chives. Ensure proper plant care through adequate watering, fertilization, and pruning.

Remove and discard severely damaged leaves to lower beetle populations. If possible, delay planting susceptible crops like beans, corn, and grapes until after the peak beetle activity period. Lastly, keep the garden clean by removing fallen leaves and plant debris where beetles might hide or lay eggs.