Japanese Beetle (Popillia japonica) is a typical scarab beetle species that belong to the order Coleoptera and family Scarabaeidae. As their name suggests, these insect species are native to Japan.
However, these insects were later introduced into the soil of the United States around the year 1916.
Although these Beetle species aren’t much destructive in Japan, in North America they are noted as one of the most destructive insect species that are pests of about 300 species of plants, shrubs, grasses, trees, and vegetation.
A typical adult Japanese Beetle measures about 15 mm (0.6 in) in length and 10 mm (0.4 in) in width.
An adult Japanese Beetle generally has a bright iridescent green color with coppery-brown colored wing covers or elytra.
These insects are usually a big threat to a wide variety of plants and vegetation for which their control becomes very crucial in American soil.
These insects are scattered all across the world in today’s scenario.
Let’s explore more about these insects and discover some of the most fascinating and interesting facts concerning their lives and livelihood!
11 Interesting Facts About Japanese Beetles
This article intends to present the 11 most important and exciting facts relating to the lives, livelihood, lifespan, feeding habits, attractions, and predators.
The importance of Japanese Beetles in the environment and their role in maintaining the ecological balance along with their differences with that of Ladybugs and Dogbane Beetles are also discussed at length in this article.
1. When Do Japanese Beetles Come Out?
Japanese Beetles generally come out during the daytime. They are most active during the summertime and can be seen foraging in the gardens from morning till evening when it is warm.
They are generally active from the late summer months of mid-July to mid-August or September. These insects are therefore seen outside, foraging for food or feeding on them, during the time when it is a warm, sunny day.
Where Do Japanese Beetles Go at Night?
Since Japanese Beetles are most active during the daytime, they generally take rest in their nests during the night hours.
Japanese Beetles are known to make their nests at a depth of a few inches under the ground and sleep there. Thus, Japanese Beetles spend their nights resting in their few inches deep underground nests.
2. What Do Japanese Beetles Eat?
Japanese Beetles feed on a wide variety of plants, shrubs, grasses, trees, fruits, vegetables, and insects. They aren’t picky eaters; however, they seem to have some favourite food supplements.
A Japanese Beetle’s diet includes roses, sassafras, Norway maple, Japanese maple, asparagus, plum, corn, black walnut, birches, vegetables, and crops.
These insects are regarded as pests of more than 300 species of plants, trees, and vegetation. Also, it must be mentioned that Japanese Beetle larvae usually feed on the roots of trees, shrubs, plants, and grasses.
3. What Eats Japanese Beetles?
Any predator in the environment that has an insectivorous dietary preference and consumes a variety of food items, is likely to attack, kill, and feed on Japanese Beetles.
Some of the birds that feed on Japanese Beetles include Starlings, Robins, Crows, Sparrows, Blue jays, Ducks, Wild Turkeys, and Cardinals.
Some of the other predators that feed on these insects are Raccoons, Skunks, Moles, Shrews, Spiders, Ants, Ground Beetles, Stink Bugs, Assassin Bugs, etc. The above-mentioned mammals, along with Opossums, are also known to feed on Japanese Beetle larvae or grubs.
4. Why Do Japanese Beetles Die Easily?
Japanese Beetles generally die very fast and easily since they have to encounter a number of threats in nature and usually have a very short lifespan.
Japanese Beetles usually are active for only about 4 to 6 weeks from mid-July to mid-August or September. They face numerous threats, especially the danger of predators, in this short period of time.
There is a wide range of creatures that feed on these Beetle species which reduces the life expectancy of these Beetles.
Also, Japanese Beetles spend most of their active time in warm, sunny daytime. This becomes an important condition for their survival without which they tend to die easily.
5. How Long Do Japanese Beetles Live?
An adult Japanese Beetle lives for about 30 to 45 days, that is for about 4 to 6 weeks, starting from the summer months of middle or late June through August or September on average.
Their life cycle begins with their egg-laying during their active seasons, that is from June to September.
Female Beetles lay their eggs around 2 to 3 inches deep inside the soil. The eggs grow into grubs and survive under the ground by consuming the roots of plants.
During the winters, these grubs move deeper, around 6 to 8 inches, into the soil. These grubs grow into adults and gradually come out of their underground habitation during their active seasons.
6. What Attracts Japanese Beetles?
Japanese Beetle species are mostly attracted to the scents of some kinds of fruits, flowers, and plants that they love to feed upon. These scents along with the scents of other Japanese Beetles attract these insects to yards and gardens that have open patches of grasses.
The plants that attract Japanese Beetles the most include Japanese maple, Norway maple, birches, cherry, plum, peach, grapes, roses, sassafras, lindens and elms.
These plants are most likely to get destroyed by Japanese Beetles since these are the major attractions of Japanese Beetles in a yard or garden.
However, there are several trees and plants that are much less attractive to Japanese Beetles. These include red maple, silver maple, tulip tree, red mulberry, and common lilac. They also hate several scents such as Peppermint oil, neem oil, and teaberry oil.
7. When Do Japanese Beetles Go Away?
The Japanese Beetle season typically ends around the late August or September months. They gradually die and go away after the end of their active months.
Once their seasons come to an end, Japanese Beetles usually die because of temperature and climate. These insects thrive on warm and sunny days but aren’t able to survive for a longer period of time when temperatures drop.
During the winter months, the Japanese Beetle eggs develop into grubs and survive by living deeper, around 6 to 8 inches, under the ground. They emerge once again when the weather conditions are favourable and summers have arrived once again.
8. When Is the Japanese Beetle Season?
Japanese Beetle season is typically the period when adult Japanese Beetles are seen above ground and are most active. Their season falls between mid-June to mid-August or September.
During their seasonal period, Japanese Beetles are found to be most active feeding on a lot of vegetation and ultimately destroying them. Because of this, Japanese Beetles are considered a serious threat to a large number of plants and vegetation during this period of time.
At the end of their season, they gradually die off because of changing climate and temperature. They once again emerge from the ground when the temperatures rise again and their season revives in mid-June to July months of the next year.
9. What Are Japanese Beetles Good For?
Other than being a serious problem for the gardeners, Japanese Beetles play an important role in the proper functioning of our ecosystem.
Japanese Beetles are used to control a wide range of insects that are present in the soil and above ground which is responsible for havoc damages.
These insects act as a predator of more than 200 species of other insects that are recognized as serious pests by farmers and gardeners.
Thus, Japanese Beetles help to control the insect population present in the soil and in turn maintains the ecological balance.
10. How To Tell the Difference Between a Ladybug and A Japanese Beetle?
Although Ladybugs and Japanese Beetles are both Beetle species, they aren’t the same and rather have many differences that may help us in order to identify and distinguish between the two Beetle species.
While ladybugs are most beloved by people as they want these insect species in their gardens, Japanese Beetles are primarily seen as agricultural pests that infect a farm or a garden by causing serious damages to plants and crops.
Both of these insects differ from each other on the basis of their physical appearances. Ladybugs are usually smaller in size and have black-dotted backs with a bold red colour, whereas Japanese Beetles are brownish in colour with an iridescent green appearance.
Also, while Ladybugs take 1 or more months to reach adulthood, Japanese Beetles, on the other hand, take only 3 to 4 weeks to reach adulthood.
11. How To Tell the Difference Between Dogbane Beetles and Japanese Beetles?
Dogbane Beetles and Japanese Beetles are often considered similar insects, primarily because of their similarities and iridescent appearance. But there are many differences between the two insect species that are noteworthy.
Japanese Beetles belong to the family Scarabaeidae, but Dogbane Beetles belong to the family Chrysomelidae marking both these insects as a totally distinctive group of insects. These insects differ considerably from each other on the basis of their physical appearances.
Generally, Dogbane Beetles are oval-shaped insects with a full-body iridescent blue-green appearance and a metallic copper or crimson shine, but Japanese Beetles, on the other hand, have an iridescent copper elytron and a green thorax.
Also, Dogbane Beetles are usually smaller in size than Japanese Beetles. There are other significant differences between the two insect species too that are based on their own behaviours and peculiarities.