Japanese beetles (Popillia japonica) are the worst nightmares of gardeners due to the extent to which they cause damage to gardens, particularly for organic producers.
In addition to this, they pose a severe challenge in managing them for growers. However, Japanese beetle traps present the goal of organic management of this destructive pest. It actively feeds on edible and ornamental plants.
Green spring garden
Let’s talk about Japanese beetles and their mass trapping to prevent the garden from this seasonal pest.
What Are Japanese Beetles?
Japanese beetles munching on the flower of an edible plant
Important Characteristics of Japanese Beetles:
| Common name | Japanese beetle |
| Scientific name | Popillia japonica |
| Family | Scarabaeidae |
| Order | Coleoptera |
| Host plants | Adult beetles feed on almost 300 species of plants, including flowers, vegetables, trees, shrubs, fruits, field crops, and turfgrass |
| Distribution | North America |
| Control methods | Difficult and expensive to control, but the Japanese beetle trap is considered a practical approach to keep their numbers small |
| Japanese beetle size | 1/3 to 1/2 inch long |
| Native range | Japan |
Japanese beetles are an invasive species which means this pest has a wide host range and poses a severe threat to growers.
Their host range includes roses, peaches, grapes, apples, and basswood. On the other hand, their young or nymphs prefer to feed on roots of grasses and vegetables and pose severe problems for landscapes and vegetable gardeners.
What is a Japanese Beetle Trap?
A Japanese beetle trap consists of a yellow card attached to a small bag or box. The top part of the trap has a pheromone (a natural sex attractant) as bait to lure the beetles.
These traps are made to attract and trap Japanese beetles. The sex pheromones attract Japanese beetles, and once they are in the bag, they cannot leave and fly back.
Japanese beetle trap—best pest control strategy
The lures are comprised of various chemicals. It may contain the female sex pheromone (pheromone traps), which attract the male.
At the same time, the second lure chemical includes the scent of Japanese beetle’s favorite food items and dead flowers. This scent attracts both male and female Japanese beetles.
The beetles sense these scents through their antennae in the air and travel towards the smell source. Beetles fall into the trap from both inside and outside.
As the large numbers of beetles congregate in the web, they release more pheromones that attract more beetles to end up in the trap bag.
Do Japanese Beetle Traps Work?
A group of adult Japanese beetles foraging on host plant leaves
The answer is yes. They trap Japanese beetles and prevent landscapes and vegetables from being damaged. However, correctly placing traps in gardens is critical to controlling their numbers effectively.
Note: The central question in using Japanese beetle traps is whether they prevent plants from damage. If not, it is not working, and the gardeners should switch to alternative methods.
The traps attract more Japanese beetles flying into your garden like any trap, such as yellow sticky traps. For example, these traps can attract more beetles, and only up to 75% end up in bags.
At the same time, the rest of the beetles will leave the bags and make their way to the garden, where they will actively munch on your favorite plants and lay eggs for the following year’s cycle.
Benefits of Japanese Beetle Trap
Like other insects traps, the trap for the Japanese beetle helps the growers
- Identifying the intensity of the Japanese beetle infestations during the beetle season ultimately helps the gardeners device control strategies
- These traps even help detect small numbers of Japanese beetle in your garden or landscape
- The trap capacity is four times higher than other pheromone traps
- In addition, the use of sex pheromone in traps attracts males more than females and plays a vital role in the control of beetles populations for the following years.
A side-by-side comparison of two different traps used for trapping beetles and sucking pests of garden crops and landscapes
How to Use Japanese Beetle Traps Effectively?
The effectiveness of Japanese beetle traps depends on the following tips:
Traps for Japanese beetle with their beetle trapping capacities Photo Credit
Where To Place The Traps To Work Effectively?
The trap placement is critical to capturing the invasive beetles effectively. Therefore, please do not place the traps near their favorite floral scent or host plants.
Instead, set the traps as far as possible, such as 30 feet away, to trap Japanese beetles from the area where they are causing damage. Also, avoid hanging the traps for Japanese beetles near their favorite vegetable foliage.
Trap for Japanese beetles hanged away from their tasty foliage for trapping
The best place to hang traps is non-flowering shrubs and trees. Keep the traps four feet above the ground to prevent damage to foliage.
Note: During windy and heavy rain, shift the traps to a protected site.
Traps Catch More Than One Pest of the Garden
The traps for Japanese beetles control these bugs and trap another pest which is oriental beetles. These beetles (oriental beetles) feed on the roots of turf grasses, ornamental plants, fruits, and garden vegetables.
Oriental beetle—the destructive pest of lawn grasses, vegetable, and fruit crops
Keep the Traps Fresh
Regularly check the traps because the lures in traps can dry out and lose their functionality. Moreover, the bag full of dead beetles can stop working. To avoid these problems, add the lures per product label instructions and change the load to full of dead bugs every four days.
A collection bag full of dead beetles trapped through the lure and ready for disposal
Set the Traps at the Right Time
The seasonal activity of the Japanese beetle begins in June, July, and August. Therefore, the traps will be most effective during this season (early summer) and will catch as many beetles as possible. Also, during the early season, beetles did not have much mating and egg-laying, and easy to control their numbers for the entire growing season.
Alternate Method to Get Rid of Japanese Beetle
Other than traps, the following methods also work best to eliminate the Japanese beetle. Such as
Hand Picking
Hand-picking these invasive beetles will help manage their infestation and protect the plants. Handpicked and dropped them in a container full of soapy water or crushed.
Hand-picking of invasive beetle to safeguard the garden plant from damage Photo Credit
Handpicked beetles in a container—which is full of soapy water
Homemade Insecticide for Japanese Beetle
Soap water plus vegetable oil for the treatment of beetles, either hand-picked or foliar spray
To prepare the homemade insecticide, we need
- Take one tablespoon of mild dishwashing liquid
- One cup of vegetable oil
- One cup of rubbing alcohol
- Four cups of water
Mix all the ingredients in a bowl, pour into a spray bottle, and use it as an insecticide against Japanese beetles. Even these homemade pesticides are effective against their larvae or grubs.
Note: To get rid of this invasive beetle, this homemade insecticide provides the best protection in the yard.
Use Neem Oil Spray to Kill Beetles
Neem oil spray to control Japanese beetles in the yard
Neem oil is effective against aphids, mealybugs, whiteflies, and scale insects, but it also eliminates the Japanese beetle problems in the yard. The neem oil spray dissolves the outer body covering of these pests and kills them.
In addition, the frequent applications during June, July, and August will prevent foliage from being damaged.
Prepare the neem oil spray as follows,
- Mix one teaspoon of neem oil per gallon of water
- Add one tablespoon of dish soap (emulsifier)
Mix all the ingredients in a bowl and pour into a spray bottle, and be ready for application.
Frequently Asked Questions
What is the Natural Predator of the Japanese Beetle?
Japanese beetles are destructive pests of more than 300 plant species and actively munch on their foliage. Therefore, to kill these invasive insects, various methods are used. One such example is the introduction of their natural enemies, and there are plenty of them.
The natural predators of beetles include robins, crows, catbirds, sparrows, bobwhites, woodpeckers, and purple martins. They actively feed on them and keep their populations below the economic threshold.
When Should I Set my Japanese Beetle Traps?
The ideal time for trap setting is early summer (during June, July, and August) because they are out and migrating for host plants at this time of the season. Also, there have not been any mating and egg-laying done. So, these pests can easily be trapped and managed.
How High Do You Hang a Japanese Beetle Trap?
The ideal placement of traps for Japanese beetle is
- 30 feet away from tasty host plants
- 4 feet above the ground to protect against the damage of leaves.
It is best to place the traps near non-flowering host plants, fruit trees, and shrubs.
Do Sticky Traps Work for Japanese Beetles?
Yes, sticky traps work like magic in the management of Japanese beetles. These traps are more effective in reducing the population of neighbors because their placement is far away from the host plants. So, these are helping the plants of your neighbors more than yours.
How Do You Permanently Get Rid of Japanese Beetles?
The Japanese beetle traps help detect their infestation and assist growers in selecting the proper practices to get rid of them. First, spray the plants with neem oil or Japanese beetle killer (pyrethrin-based insecticides) at the first sign of their infestations.
Pyrethrins effectively kill Japanese beetles and are also non-toxic to the environment, humans, and pets. While spraying plants with this insecticide, cover the beetle entirely with spray.
How Effective is Milky Spore?
Milky spores are bacteria famously known as Paenibacillus papillae and are the only best solution to get rid of Japanese beetles in landscapes completely. It is applied as dust on turfgrasses to stop the feeding of adult beetles and their grubs. It is only effective in killing Japanese beetles and their grubs.
Why Do I Have So Many Japanese Beetles?
It is because your yard has many factors that support the growth and development of Japanese beetles. Such as, your garden has its favorite host plants and lacks natural enemies. Combining these two factors helps in the tremendous growth of beetles in your garden.
What Kills Beetles Instantly?
Pyrethrin-based chemicals instantly kill the beetles. These chemicals are of plant origin—derived from the chrysanthemum flower and negatively impact the nervous system of beetles. So, to effectively kill the beetles, spray the vegetable crops with pyrethrins whenever you spot them.
Where Do Japanese Beetles Lay Their Eggs?
The clean and well-maintained grass areas are the primary sites for egg-laying. The adult beetles make tunnels (2 to 4 inches deep) in the ground and lay up to 60 eggs in each hole, where they can easily absorb soil moisture. The eggs are oval-shaped and white.
The complete life cycle of a Japanese beetle
Once the egg-laying process is completed, the female will return to food sources (host plants) for feeding until the next mating cycle starts. In this way, the female beetles lay up to 40 to 50 eggs.
Do Dead Japanese Beetles Attract More Beetles?
The dead beetles do not attract more beetles in gardens and other yards. Instead, the plant oils attract more beetles being chewed by beetles. So, to control this problem, it is ideal to set traps with baits in them 30 feet away from the target plant.
In this way, beetles get trapped in it before landing on the host plant (their favorite flowers and vegetable crops).
Sources for Further Reading
- Dudenhoeffer, A. (n.d.). // Missouri Environment and Garden News Article // Integrated Pest Management, University of Missouri. Integrated Pest Management University of Missouri. Retrieved April 6, 2022, from https://ipm.missouri.edu/MEG/2018/1/mass_trapping_japanese_beetles/
- Don’t fall into the Japanese beetle trapping trap. (2021, March). UMN Extension. https://extension.umn.edu/yard-and-garden-news/dont-fall-japanese-beetle-trapping-trap
- RESCUE! (2021, February 1). Japanese Beetle Trap. Rescue. https://www.rescue.com/products/traps/japanese-oriental-beetle-trap/
- Lipford, D. (2019, November 14). Do Japanese Beetle Traps Really Work? Today’s Homeowner. https://todayshomeowner.com/do-japanese-beetle-traps-really-work/
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