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how to get rid of japanese beetles

How to Get Rid of Japanese Beetles

Japanese beetles have been the bane of North American gardeners since 1916. One-hundred years later, gardeners still struggle with the pests. One of the most asked gardening queries is, how to get rid of Japanese beetles. This is especially true in areas of the North East, Mid-West and South East where their level of concentration is in the category of infestation. The Japanese beetles move in large swarms, razing the lawn, garden and all else their path, laying eggs in the soil, and leaving behind a swath of destruction.

Deemed one of the most damaging pests in the United States, the Japanese beetle is particularly challenging to control because they have very few natural predators. Unlike in their native Japan where the population stays in check naturally.

With some determination and the proper information, it is possible to discover how to get rid of Japanese beetles.

What do Japanese Beetles look like?

Identifying the Japanese beetle is the first step in eliminating the pest from gardens, bushes, and trees. The beetle’s oval shaped body is approximately one-half inch long and slightly less than one-half inch wide with a deep green thorax.

Japanese beetle

The beetle has six legs and thin semi-opaque hind wings, which hardened copper-colored front wings, cover. Also called elytra, the front wings are extremely iridescent; scientists surmise that this is an adaptation, which developed to help beetles identify each other.

Japanese Beetles Life Cycle

There are six stages to a Japanese beetle’s life cycle, which typically lasts one year, although the beetles may have extended life cycles in cooler climates.

The life cycle begins sometime between late summer and early fall when Japanese beetles lay their eggs on a lawn, in a garden with access to water, or a grassy area.

Beetle eggs hatch between late summer and mid- fall. Beginning in late fall, grubs begin to burrow deep underground, some will go as much as twelve inches deep to avoid winter temperatures.

They will remain dormant until very early spring. In the spring,when water from the spring rains arrives, grubs awaken and begin feeding on grass roots.

After the spring feeding, the grub pupates and turns into an adult Japanese beetle. The adult beetle spends the entire summer feeding, mating, and laying eggs.

How many eggs do Japanese beetles lay?

The adult female Japanese beetle will lay between forty and sixty eggs.

This occurs in several periods over the course of the summer normally reoccurring every twenty-four to forty-eight hours when between one and five eggs are laid at a time.

When do Japanese Beetles lay Eggs?

The Japanese beetle lays eggs over a period of time during the late summer and early fall.

When do Japanese Beetles hatch?

Japanese beetle eggs hatch between late summer and mid- fall, during this time they feed extensively on the roots of whatever is near to them.

How long Japanese Beetles live?

The life span of a Japanese beetle is normally one year long.

Of that time, about ten months are spent underground maturing. The rest of a beetle’s life is a continuous cycle of eating, mating, and if the beetle is female, laying eggs.

What do Japanese Beetles eat?

Japanese beetles are voracious eaters with the ability to destroy large amounts of foliage. An individual beetle does not do much harm to a garden.

japanese beetles

However, Japanese beetles prefer to feed in large groups. These groups of beetles cause significant damage to whatever they choose to eat.

Japanese beetles consume on about 300 different varieties of foliage, eating leaves, flowers, and fruit, specifically fruit that is overripe or damaged. They typically forage in groups.

Once a group of Japanese beetles identifies a target, they begin eating at the top and work their way downward.

The beetles feed on the top of the leaves, eating only the tissue between the veins of the leaf.

Once a group of Japanese beetles finishes a leaf, all that remains is the outer edge and veins of the leaf.

This produces a lacey or skeleton like appearance, which is a telltale sign that Japanese beetles are in the area.

The most notable exception to this is when Japanese beetles eat rose bushes, they completely devour rose petals and leaves because the rose bush leaves have veins which are delicate. When beetles significantly damage a tree, it often looks as if singed by flames.

Odors that come from beetle-damaged leaves seem to be a significant cause of the accumulation of Japanese beetles on specific plants. Beetles typically feed the most, and therefore cause the most damage, on sunny hot days.

How to get rid of Japanese Beetles on plants

The Japanese beetle is one of the most destructive pests in the eastern, southeastern, and midwestern United States. From their accidental introduction to North America one hundred years ago, until the present time, these infesting pests have distressed farmers and gardeners alike. Japanese beetles thrive in the favorable conditions found in these areas.

Japanese beetles infest the large areas of lawn and pastures that make ideal places to lay eggs. Rainy springs provide the water beetles need while maturing underground.

Hot summer weather is perfect for Japanese beetles, as they are most active on hot and sunny days. Humans unknowingly assist the beetles with the tasks they do to care for their gardens and crops.

Tilled soil, water, and the discouragement of other pests all make a good ecosystem for the beetles. Clearly, the Japanese beetle is not a friend to humans and causes great amounts of destruction and frustration.

Even after identifying and understanding these pests, the question remains, how to get rid of Japanese beetles.

Japanese Beetles on Roses

Rose bushes are a favorite of the Japanese beetle. They are able to consume nearly one-hundred percent of a rose bush, because of the delicate leaf veins.

There are methods of ridding roses of Japanese beetles, the method judged as most effective is Milky Spore, takes several years of diligent effort to achieve success.

At the initial sign of Japanese Beetles, apply a product called Milky Spore to the grass or lawn near gardens. Japanese beetle grubs eat the spore, which has a type of bacterium in the spore that kills the pests.

Killing the maturing beetles produces more of the milky spore, this spore will, in turn, kill more beetles underground. It can take several years of this killing cycle to curtail beetle infestations.

It is important to note that killing of adult Japanese beetles on rose bushes during this time is a necessary part of successfully getting rid of the pests.

However, the insecticide used must not kill the Japanese beetle grubs. Killing the maturing beetles will stop or slow the spread of the Milky Spore, which in turn stops or slows any progress made by the previous use of the spore.

Japanese Beetles on Basil

Basil is a favorite of Japanese beetles as it has delicate leaves that do not impede the beetle’s consumption.

Since humans consume basil, take different measures to rid the plants of adult Japanese beetles, the insecticide used on roses could have significantly harmful effects if accidently ingested by a human.

Using Milky Spore to kill maturing beetles underground is acceptable for this and other infested varietals.

Saving basil from Japanese beetles is a labor-intensive project, but a worthwhile one. Begin by hand picking or knocking all visible adult beetles from the basil into a container filled halfway with water and a few drops of dish soap.

After removing all visible beetles, thoroughly spray the basil with an insecticidal soap.

These are useful in curtailing a variety of plant pests, including Japanese beetles. Spray so the whole surface is wet because the insecticidal soap is most effective via direct contact with the Japanese beetle.

Insecticidal soaps are non-toxic, considered a safe alternative to harsh pesticides, and useful in organic farming. To prevent recurring infestations, cover basil plants with lightweight row covers.

Placing wire cages wrapped with mesh row covers will provide basil with extra protection from Japanese beetle infestation.

Japanese Beetles in Garden

Japanese Beetles in the garden are particularly challenging, especially if the garden is sizeable. Because the voracious pests consume more than three hundred types of foliage, there is a strong likelihood that most; if not all of the garden will attract Japanese beetles.

To prevent accidentally ingesting a chemical pesticide the use of organic repellants is best in a garden.

Neem oil is widely used for organic farming. It effectively repels Japanese beetle.

Studies have shown that neem oil is not toxic to mammals, beneficial insects such as honeybees, and butterflies, birds, or earthworms because it does not affect insects that do not consume leaves.

It is administered as a spray and should be applied in indirect sunlight to avoid damage.

Avoid applying neem oil in extreme heat, as this may also cause harm. Use neem oil once a week until there are no signs of Japanese beetles. Neem oil is also effective, if you want to know how to get rid of spider mites.

Japanese beetles on Fruit Trees

Controlling infestations of Japanese beetles on fruit trees is challenging due to the fact that the same conditions farmers use to cultivate good crops attract Japanese beetles to the fruit trees.

Using environmentally responsible methods to control Japanese beetles is often difficult and typically requires more than one effective method to curtail the pests.

A product that has displayed good results for fruit growers is Surround WP. This white clay material coats the exterior of foliage and fruit to create a barrier that protects against Japanese beetles.

In trials, Surround WP has performed very well against the Japanese beetle. The best results came when fruit trees received two or more treatments with Surround.

This approach to Japanese beetle control may require the removal of residual white coating on the fruit before selling the fruit.

A second method, which is effective, especially when used in conjunction with Surround, is using a soil-applied pesticide. Japanese beetles favor moist, grassy areas for laying their eggs. This habitat is abundant on most fruit farms.

Applying a pesticide to the soil is an effective way to reduce the overall population of Japanese beetles while they are maturing underground.

This approach will reduce the number of Japanese beetles the following year. An alternative to this would be using spore to combat the underground pests.

Japanese Beetles Traps

For several decades, when marketing Japanese beetle traps to gardeners, producers of these promised the devices would lure and trap the pests, creating a beetle free environment.

For several decades, gardeners who used the discovered that those promises fell short. The traps were successful at luring Japanese beetles and even catching some inside the trap, but the traps created the opposite of a beetle free environment.

The typical Japanese beetle trap contains pheromones and a floral lure. Initially, the attractant materials sound like the perfect way to lure insects who spend their days feeding and mating.

However, they entice far more Japanese beetles than they trap. Hanging a Japanese beetle trap near infested foliage practically guarantees the infestation will grow exponentially.

Some gardeners receive advice to use these, but to place them away from infested areas. However, it is still enticing more beetles than it will catch and the remainder will infest any other nearby living things. The best advice regarding these to avoid them.

Which Plants repel Japanese Beetles

Because the list of varietals consumed by Japanese beetles is so large, it is hard to imagine many, or any, which can actually repel infestations of the pests. The kind of foliage that will most likely assist gardeners in driving away Japanese beetles must be strong smelling and preferably taste bad to the beetle.

  • Tansy
    This herb is a member of the aster family and for centuries, it has repelled many varieties of insects. Gardeners and some farmers use this herb as an organic way to keep Japanese beetles at bay. Tansy’s strong scent either deters them directly or makes it difficult for the beetles to find their host.
  • White Chrysanthemum
    These flowering beauties emit a strong scent which Japanese beetles avoid.
  • White Geranium
    These have a strange paralyzing effect on the Japanese beetle. Feeding on white geraniums paralyzes Japanese beetles for up to twenty-four hours. Although the beetles do not die, they typically become victims of other creatures in their paralyzed condition.
  • Garlic, Onion, Leeks and Chives
    The scents of these are particularly pungent and repel Japanese beetles. In some cases making a spray with oils from these along with soap is also helpful.
  • Marigolds
    This flower repels various insects including Japanese beetles, however, the French marigold tends to attract spider mites.
  • Catnip
    A member of the mint family, catnip will reduce the instances of Japanese beetle infestations.
  • Citronella
    Elements of citronella are repellants of many pests, most commonly mosquitoes,but the citronella’s strong scent also drives away Japanese beetles.

How to prevent Japanese Beetles

Ideally, gardeners and farmers would prefer preventing infestations of Japanese beetles to expending time, resources, and effort trying to remove the pests.

This is especially challenging because the Japanese beetle consumes a great variety of foliage and has few natural predators in North America.

Consider planting Japanese beetle repellents or invest in varieties that resist Japanese beetles. It is unknown why while certain plants may not repel Japanese beetles; the beetles are not interested in consuming them.

These varieties include lilacs, hydrangeas, begonias, flowering dogwood, forsythia, magnolia, holly, boxwood, and dusty miller.

The introduction of predators is a helpful strategy and can prevent Japanese beetle infestation.

Wild and domestic birds feed on Japanese beetle larvae when they are close to the surface of the ground.

Certain species of wasp are predators of Japanese beetles, as are some spiders, assassin bugs, and Tachinid flies.

Since few creatures in North America are predators of the Japanese beetle, cultivating them to combat beetle infestations is highly unlikely.

Conclusion

While there is no single comprehensive way to completely remove Japanese beetles. There are several useful methods can help greatly reduce or eliminate these invasive pests.

A two-tiered approach targeting both the adult beetle as well as the maturing beetle is usually best, but in most instances, two different types of repelling agent are necessary, so that adult beetles die and cease to replicate and larvae die without increasing the Japanese beetle population.

While hanging a commercially available Japanese beetle trap seems to be a good idea, these attract more beetles than they catch and nearly guarantee larger infestations of Japanese beetles in the long run.

An insecticidal soap is a safer option and it is easy to spray the lawn, roses, and plants with a soap mixture

Carefully choosing plants which Japanese beetles refrain from infesting is a good way to prevent infestations, while maintaining an attractive landscape.

Planting as companion plants, species, which are repellants of Japanese beetles, is another way to help curtail beetle infestation, this is very helpful when cultivating roses because roses are a Japanese beetle favorite.

Unfortunately, Japanese beetles are thriving in North America, just as they have for the past one-hundred years.

Getting rid of them may not fully be possible, but reducing their impact is a good first step.

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