Do Japanese Beetles Bite? Why Do They 'Bug' Us Constantly?

Japanese beetles are shiny green scarab beetles that you may find lurking around your plants and flowers during the warm summer months.

Though the larvae can live for over a year, actual adult Japanese beetles only emerge during the summer, and die off in a month or two! Grubs are born at the beginning of the year, and spend the rest of the year feeding and maturing until they emerge as the next generation of Japanese beetles in the following summer.

These beetles have garnered quite a fierce reputation for themselves, with their scary-looking mandibles and sharp tiny teeth! But these help them to survive.

Large groups of these bugs can make quick work out of any vegetable garden or potted flowers, which is why it is very important to keep a close eye on them to stop their numbers becoming uncontrollable. However despite their aggressive nature, do Japanese beetles bite humans?

What does a Japanese beetle look like?

Japanese beetles, a type of scarab beetle, are identified by their shiny, metallic colors. Japanese beetles have shiny, iridescent copper-colored wings and emerald-colored heads and upper bodies. Their antennae are three-pronged and look like small tridents. They also have small fluffy white patches under their wings, on both sides of their bodies.

They are quite large as far as insects go, measuring between 1/3 in (0.7 cm) to 0.5 in (1.3 cm) in length. Japanese beetles lay eggs underground, which are oval-shaped and white in color.

They double in size right up until they hatch into larvae. Japanese beetle grubs, or larvae, are longer than the adults, reaching 1 in (2.5 cm) in length!

They have brown heads and grayish-black bodies and can be observed curled up in a C-shape. The last stage they go through before changing into adults is the pupa stage, in which the larvae encase themselves in cream-colored capsules, which become redder as they mature before fully grown beetles finally emerge.

Are Japanese beetles aggressive?

These beetles can be very aggressive and are very destructive in groups. They use their strong, sharp mandibles to tear through leaves, and will bare them at you if you get too close!

If you try to get rid of these critters by attempting to pick them up, be prepared for them to attempt to bite you, resulting in a pinch which is usually harmless.

They also have rough, spiny legs which may prick you as they rub against you. However, their legs do not hurt, but rather cause an itchy sensation.

Japanese beetles are dangerous to your garden at all stages of in the life cycle. As adults mate underground and lay eggs there, newly hatched grubs can be found eating away at the roots of plants in order to grow.

Once they transform into adult beetles, they dig their way out of the soil and begin to eat the plants that are above the ground.

Though adult Japanese beetles have quite a short lifespan, ranging only from 30-45 days, they populate very quickly, with female beetles laying one to five eggs in the soil after mating on food plants. They are also very difficult to get rid of because of their tough exterior and aggressive nature.

Their actual life cycle lasts around one year, with grubs spending the winter months slowly feeding on the roots of plants and growing.

You will find these beetles on plants and in vegetable gardens during the warm summer months, which is when the adult beetle population starts emerging from the soil.

They will stick around and eat through a number of leaves and flower petals until fall, which is when the majority of adult beetles will begin to die off due to colder temperatures. The last batch of Japanese beetle eggs is laid during late fall, which is when the new life cycle begins.

These grubs will turn into adults for next summer.

How do you prevent a Japanese beetle bite?

Japanese beetles do not bite. They have tough mandibles which are helpful for them to chew through plants and organic matter, however, these are simply not sharp, nor big enough to actually break through human skin.

They mostly use their teeth to eat and chew on leaves and flowers, as they are known to cause widespread destruction in parks and gardens! Though Japanese beetles will not bite, you can still tell that they are aggressive by the way they bare their mandibles or lift up their hind legs if you get too close.

These are defense tactics, usually employed against larger insects, birds, or rodents trying to feed on them.

What are the natural predators of Japanese beetles?

Japanese beetles appear to be rampant and destructive in North America where they are an introduced species. However, they are very well controlled in their natural home of Japan due to the availability of their natural predators. They are usually eaten by birds, small mammals, and even other insects!

In America, Japanese beetles with their shiny shells can catch the eye of native birds like turkeys, ducks, sparrows, crows, robins, and blue jays, who pick up stragglers with their beaks and gulp them down in one bite.

They are also eaten by raccoons, who are very fond of insects, as well as skunks, moles, large spiders ground beetles as well as ants.

A unique predator of Japanese beetles are Tachinid flies. These crafty flies land on top of Japanese beetle adults and lay their eggs on their backs, which hatch within a day and bite their way into the inside of a beetle's bodies.

They then slowly devour the beetle from the inside out, leaving behind only a hollow shell of the insect.

As Japanese beetles can cause a lot of damage, often tearing through plants and flowers quite rapidly, there is ongoing research about potentially introducing their natural predators into Japanese beetle-infested environments.

However, these beetles seem to be causing damage faster than they are being eaten, which leaves using pesticides as the best choice in trying to get rid of them.

The best way to naturally rid your garden of Japanese beetles is by waging combat against adult beetles during the summer before they can mate, or getting rid of beetle eggs in the fall before they hatch.

You can either use mild pesticides on your plants or manually pick your beetles and drop them into buckets of soapy water, which will kill them off.

Leaving dead beetles in the vicinity will also ward off other beetles, which take the scent as a sign to stay away.

The presence of Japanese beetles at a location seems to attract more beetles, which is why it is very important to rid the area of any existing beetles before the situation grows out of control.

A long-term solution is to make your garden more bird-friendly by laying out birdseed and water bowls, which will attract local birds to the area. Birds will effectively pluck out most of the beetles for you. Refraining from watering your plants too much will also help, by drying up Japanese beetle grubs and the eggs hidden inside.

Fun Facts About Japanese Beetles

Japanese beetles aren't native to the US and were accidentally brought over in a shipment of iris bulbs from Japan in around 1916, and spread throughout 30 states since then. As they are not a native species, their natural predators are also quite low, which leaves them free to wreak havoc among plants and crops in large groups!

Japanese beetles are very fond of sunlight and are diurnal in nature. They can be seen perching on plants and chomping through leaves when the Sun is out, even being more prone to mate on warm days. They retreat to rest once night falls.

Japanese beetles seem to be especially attracted to roses, and can be found invading patches of yellow roses! More of their favorite plants are hibiscus, grapes, Japanese maple, and raspberries! However, they are not very picky. They can be founding feeding on over 300 different plant species.

They eat only the upper side of leaves, leaving behind the 'skeleton' which includes the veins and middle. This a sign for farmers that there area Japanese beetles lurking around.

They use their sharp, tiny teeth to chew their food before swallowing it. In fact, the name beetle comes from the Old English word 'bitela', which translates to 'little biter', quite appropriate for these tiny insects! Using their teeth to thoroughly chew their food seems to be a common trait in all beetles.