Japanese Beetles: Basic Information, 6 Fun facts & 5 Ways to Get Rid of Them

Basic information about Jalpanese beetles

1. Appearance and size

The adult Japanese beetle is one which may be easily identified upon the first look. Measuring at almost half of an inch in length and a quarter in width, the beetle is a broadly backed insect with an overall oval shaped body. Sporting a metallic green body with tinged embedded gray streaks all over, the beetle is quite a looker. Upon the back of its shell’s sides, two copper colored wings with a brownish touch, rest against its back. The wings are not long or wide enough to cover the abdomen but are strong enough to carry the beetle around. Patches of white hair may be commonly observed on the sides of the abdomen of the Japanese beetle which brings it apart from the rest of the Popillia family (Latin name for Beetle).

For most of the two months of their shortly spanned lives, the Japanese beetles discover the optimum times for their activities during the end of the month of June. From here and through to the end of September, they resume the activities of what they are known to do best. When the time comes and the seasons shift, the Japanese beetle begins to die off one by one due to intense climate changes in which they cannot survive, let alone thrive.

2. Diet and behaviour

The Japanese beetle is true to its name. Having origins from within the country of Japan, the beetle managed to find its way into large nesting grounds of the United States, most probably through the valleys of commerce and trading rituals observed between the two countries. The United States is said to have the largest population of Japanese beetles due to the country offering the beetles a favorable climate. Alongside the large masses of land and greenery, the beetles were also offered no natural predators against themselves. Due to this, they were allowed to feed and reproduce at an exponential rate, claiming the territory for their own.Japanese beetle on plant leaf with damage.

The beetles are attracted to leaves of specific plants, both generic vegetable crops, and flowering plants. They cause a wide selection of damage to these plants during their adult stage. Even in their larvae stage, they may feed and damage the roots of ornamental plants/trees/shrubs, to extents where the plant must be allowed to die out or to have them to be replaced.  Though their wild escapades can be controlled using a variety of methods, the beetles are a nuisance due to the behavior of their feeding itself. They are movements having been documented as in groups, where they feed together. Having an appetite for over two hundred and fifty different types of plants, they can muster massive amounts of damage to wide expanses of land, if the feed is to their liking.

Like most other organisms, the beetles are most active and thriving in warm climates. These creatures prefer to feed on plants harvesting direct sources of natural light; these spaces also become breeding spots for the Japanese beetle due to the constant source of food available for them. Here they may breed and lay eggs, while all the while migrating in large groups to other areas in the vicinity using the wind to their advantage.

3. Life cycle

The life cycle of the Japanese beetle starts off like most other insects. The eggs are laid in coveted and protected spaces, with food available at the most immediate source. The eggs are of an oval shape with a milky white texture. They are laid on the ground so they may be able to absorb moisture but also because the grubs feed on the roots of plants due to their inability at the start to reach the leaves they so desperately crave. In some cases, the grubs may migrate to another location for food and adequate soil moisture. As the situation for survival is not favorable, the migration tends to wreak more havoc to a patch of land the larvae were first laid upon.

After hatching, the larvae feed and thrive until they are ready to enter the stage of pupation from whence they may be able to turn into fully functional adults. They are typical in appearance, supporting white exteriors, and must go through five molts during the pupation stage to turn into their true adult form. Once they enter the pupation stage, they exterior on their backs turns into a reddish brown color which is transient to the time they turn into adults.

Once the larvae have turned into adults, they can do what they do best. Feed. Since their pupation stage ends during the start of the summer, the warm months allow them to be active and to work to the best of their abilities. Upon their release from their cold shells, the adult beetles start off with releasing pheromones into the air as ways to let others know where they are and if food is available or not. As the masses come together, the process of mating also begins. They mate upon the leaves of the plants which they are to devour, and it is not uncommon for one beetle to have more than four partners during mating season.

Macro of mating Japanese beetles.The female beetle will then leave the plant she feeds upon to find another safe location to lay her eggs. Up to five eggs may be laid in coveted positions where the larvae may find food upon hatching. The female will then return to the feeding grounds until another mating ritual begins, and the process so repeats. A singular female is known to lay over forty eggs in the duration of her short life.

4. Habitat

The habitats of most Japanese beetles can be found within countries supporting warm climates. As is these conditions are more suitable to their living conditions, they create small pockets where they infest and reproduce, spreading along faster if food is widely available. They may also be found in backyards that harbor vegetable gardens and flower patches. They do not have many requirements for breeding grounds except for two requirements. The first would be proper soil moisture, which they larvae require to absorb during the pupation stage. The second would be the availability of food. If the food is not available, the beetles migrate further on, dying in numbers before they can reach spaces which allow them to prosper. Incidentally, the beetles are not an issue to their native land due to the availability of natural predators keeping their population in check.

Six interesting facts

These little critters may be the worst enemy to your garden/lawn, but like all other insects, they have interesting little facts about them.

1. An army or none

The beetles release a pheromone into the air upon turning into young adults. Due to this, more beetles are attracted to space where the signal has been released. Damaged plant leaves also release chemicals into the air which attracts beetles in the vicinity to congregate together once more. A singular beetle cannot cause much damage, but a horde is what decimates the patch of green.

2. Sixty days to live

The life of an average Japanese adult is at the top most sixty days. Most life spans average between thirty to fifty days. The mating processes take one or two days tops, where the females may be ready to mate once more after a waiting period of one day.

3. Rain or shine? Most likely shine

The Japanese beetles prefer to do all their activities under direct sunlight. The warm weather allows them favorable conditions to feed and mate. If the insects are to be taken care of using pesticides, the best time would be during the mid-day where their numbers are the peak.

4. Nestled in earth

Japanese Beetle on a Bright orange Zinnia.The beetles are known to travel from continent to continent within earth shipments. Countries are known to provide different soil on order, export large quantities of earth from their homeland to help fertilize farmland. Japanese beetles are known to escape soil screening, and hide within the earth and help travel to different areas only to resume their actions under more favorable conditions.

5. Food critics

The palate of the Japanese beetle includes more than three hundred and fifty different species of plants, but like all other critics, they have a taste for certain plants more than others. The hunger of beetle tends to damage more plants.

6. Wings of steel

The wings of the beetle allow it passage to more spaces than other pests. Using the wind to their advantages, the beetles traverse long expanses of land (several miles) to feed, mate and to lay eggs where ever they find food sources.


The Japanese beetle feeds in a way where they only damage the leaf section of the plant itself. They feed upon the tissues that make up seventy percent of the leaves of the plant. Using their mouths, they puncture small holes in numerous quantities around the leaf, creating gaps which break down the internal structure of the plant itself. Due to this, the leaves are destroyed and unable to create and spread the nutrients due to their inability to photosynthesize. When this sort of issue takes place all over the plant due to the attack of the beetle horde, the whole plant eventually starts to break down in function resulting in inevitable death.

While the adult beetle feeds on the leaves, the grubs feed on the roots of the plants. By chomping down those, the plants lose the ability to gather water and nutrients from the soil below. It is an often enough observation that after a swarm has swept past a patch of land, the grass is left behind decimated and turning brown, eventually dying when the plant cannot function anymore. The adults are feeding on the topmost section leave behind skeletons of the plants that once stood tall.

When it comes to flowers though, the beetles leave a zigzag pattern around the edges of their petals. As the flowers contain no vein structure in between, then puncture holes encompass most of what makes the flower what it is.

Favorable plants for the Japanese beetle

Background of bouquet of pink blooming rose bush.Unlike most insects, the Japanese beetle has a specific taste for certain varieties of the plant which can enable them to move, mate and feed more actively than other plants. Inhibiting factors reduce by high levels if the beetles find plants that are more appealing.

Rose bushes Cherry tree Gray Birch Japanese Maples
Hollyhock Peachtree Dahlia Norway Maples
Grape Plumtree Gladiolus Sunflowers

Not only plants, but there are also specific weed types that get the beetle’s juices flowing. Removing these from within your yards may help to remove unwanted attention from the beetles.

Indian Mallow Smartweed Poison Ivy Wild Fox Grape

Ways to get rid of them

1. Natural predators

One way to rid your plants of the Japanese Beetle is by relying on natural predators which can eliminate the danger posed by pesticides or any other chemical products. One such predator that can adequately exterminate a population of Japanese Beetle is a parasitic wasp. It does so by laying eggs on the beetle which eventually hatch and feed on it, ultimately killing it. These wasps can be attracted by introducing plants that have shallow flowers, for instance, mint, fennel, English lavender, and dill.

The only disadvantage is that once the food source is depleted, the parasitic population disappears as well. For best results, Japanese beetle traps and other beetle control products should be used in combination with the natural predators.

2. Plant alternatives

As already mentioned, the beetles are fairly easy to see, and their movements are slow. As a result, they can be knocked off of the plants that are hosting them, and this is an effective means of control. Certain plant species help to repel off the beetles.Round boxwood in park.

Another simpler way would be to use knock off beetles from the bushes that they intend to devour as they are slow in movement.

Boxwood Plants Geraniums White Poplar Magnolia
Holly Dogwood Boxelder Plants

3. Bag traps

There are special bags that are used to remove beetle infestations. The bags are hung outside, while they secrete a special pheromone. Beetles in a two-kilometer radius are attracted to space and find themselves trapped within the bag. The beetles can be disposed of without killing them which makes this environmental friendly than other pest control techniques. However, the downside lies in the fact that the bag attracts more beetles into the vicinity than it helps to remove.

4. Bonide

Natural pyrethrum for the quick and easy kill of Japanese Beetles and other listed insects. This ready to use, 32 oz spray bottle is ready to start eliminating garden insects, including Japanese Beetles, with just the squeeze of the trigger.

5. Spectracide

Spectracide is a special spray that may be used if the beetle masses are growing large in numbers. It is an environmentally friendly chemical which uses natural pheromones in attracting and luring out Japanese beetles into different areas. It avoids the use of dangerous pesticides that may kill of different insects which may be needed for the habitat’s growth itself. Working in a five thousand square feet radius, it lasts the entire beetle season and helps to control the beetles using their natural instincts against themselves.


All in all the Japanese beetles would be considered an unwanted guest in anything related to green spaces. In large numbers they can cause massive damage and are a nuisance to control but once controlled, they can benefit the environment much like any other organism in a diverse habitat.

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