The Japanese Beetle is a pest that, like any other worker after a hard day at the office, during the late afternoon, will clock off and head to their evening nesting location where they will sleep on the ground in the nests they build at night.
If this beetle wasn’t so destructive, they would be remarkable.
However, for million gardeners across the whole United States, Japanese beetle season reminds them, that they are about to witness annihilation with plants of all kinds.
If this iridescent beetle has you at your wits end, this very short guide to the Japanese beetle will provide you with all the necessary information, to bring an infestation of this pest right under control!
So Just What Are Japanese Beetles?
Popillia japonica, Japanese beetles are a small, iridescent green and copper colored beetle that are a type of scarab beetle.
As the name implies, the Japanese beetle is found in Japan where beetle populations are controlled naturally by their predators.
But here, in North America, particularly the East and Mid-west, they have no predators and they have become a pest of hundreds of crops, grass, ornamentals, trees, and shrubs! Japanese beetles are very adaptable and can find a place to live in most any foliage they can find to feed on!
Identifying the Japanese Beetle
An adult Japanese beetle is a little over 15 millimeters long and 10 millimeters wide. Its wing covers are a copper color, contrasting with its iridescent green thorax and head. Under its wing covers are white coarse tufts of hair. It’s wings are light brown.
The larvae are large, curved grubs that are up to inch long. These larvae hatch in the soil and live in the soil while they actively feed on little plant roots. Once the Japanese beetles are mature, they are easily identified during the daytime when they can be found in groups eating.
Have You Noticed: You can usually see them actively eating or on the ground near the plants they have been eating?
From Larval Stowaway to Cornfield Menace…
The unchallenged journey of the Japanese beetle in North America began in the early twentieth century, when the species was accidentally introduced. This was most likely as larvae in the soil of imported plants.
Biosecurity in agriculture and environmental practices at the time were in an early stage and despite efforts such as banning imports of soil with plant materials was ineffective in stopping this species from entering into a totally different environment and ultimately becoming established.
By 1916 they had spread to New Jersey as island people making themselves at home in North America! It was too late!
The Japanese Beetle Is a Prolific Feeder
The Japanese beetle takes a highly industrial approach to dismantling large numbers of plants. Their voracity allows them to destroy crops as well as cause cosmetic damage to gardens and grounds. Groups of beetles will destroy plants by basically stripping off all the foliage between the veins of the leaves.
Based on description alone, Japanese beetles skeletonize plants by removing leaf tissue, leaving a skeleton outline – an unmistakably distinct calling card.
Fruit is not safe either as the beetle will not only focus on soft fruits, but their larvae will eat from the roots.
Caution: The grubs can produce brown patches in lawns as they will also eat the roots of grass and kill the blades, too.
And They Will Eat Just about Any Plants
The Japanese beetle feeds on over 300 species of plants with a slight preference for roses.
In the mid-west, they have made a habit of being bad agricultural pests, eating beans, grapes, cherries, apples, maize and more!
An Painfully Short Campaign
Fortunately, the life of the Japanese beetle is in seasonality so the campaigns of destruction are somewhat shorter in duration.
But in a life cycle of fewer than 40 days, the bug can do a lot damage and can reproduce by laying many eggs in your lawn and wreak havoc the next year.
Japanese Beetles Work a 9 to 5 Shift Eating Your Plants and then to their Own Nests at Night.
If you are ever wondering, where do Japanese beetles go at night? They go home to nests they build and sleep.
Japanese beetles prefer to be out and about on warm days from late Spring until about mid-August.
If you see beetles feeding at night during this time period, they are probably Northern Masked Chafers which follow a similar seasonal activity pattern as Japanese beetles, but are nocturnal.
How to Bring Japanese Beetles Under Control (Before Your Garden is Overrun)
For parts of the US, damage from Japanese beetles is an annual event, but there are ways to firefight their campaigns.
With diligence, you can use organic control and eradication methods that are adequately effective.
Here are some ways for you to try;
- Handpicking – simply pick these beetles off your fruit, vegetable and ornamentals and drop them in a bucket of soapy water. They do not have jaws that have a biting capacity strong enough to bite humans.
- Neem oil – this organic pesticide can be very effective as the ingested oil will kill the larvae of the Japanese beetle.
- Covering crops – netting and covering crops will reduce damage, but you will need to uncover the crops for a time to have them accessed by pollinators and others.
- Traps – there are pheromone traps to purchase to attract the beetles to, but a simple fruit trap of rotting fruit cocktail set in a bucket of soapy water that is effective.
- Sacrificial plants – geraniums are the “cat-nip” of the Japanese beetle. It will attract them to this plant, but they will be woozy after eating, and therefore will be easy to round it up and get rid of them.
- Natural predators – parasitic nematode and wasp species can target and kill these beetles.
After you have shown them the door, here are some methods to help prevent their return:
- Cultivation is always key to keeping pests at bay.
- You can terminate Japanese beetle grubs early in their season in variable secretions as immature ones, in your lawn, by inoculating the milk spore fungus into your lawn so when they emerge, they will die.
- You can eradicate grubs by spraying a dilute soapy water on your lawn that will make Japanese beetle larvae surface, whereby birds will eat them.
- Distribute ornamental roses and other preferred plants around your property. Companion planting will also help protect crops.
In Summary.
While it may seem inconsiderate that the Japanese beetle can spend its days eating those plants and crops that you are working hard to cultivate and grow, thankfully there are some options you can use to attempt to get your plants through the Japanese beetle season with the minimum of harm.