June Bug vs Japanese Beetle: What are the Differences?

Written by Emmanuel Kingsley
Published: May 29, 2022
© Sean Harris acts238/Shutterstock.com
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The June bug and the Japanese beetle are similar in appearance and are both beetles within the Order Coleoptera and Family Scarabaeidae. Due to this, it may seem difficult to distinguish between them, but there are indeed notable differences.  By the time we are done, you will be able to accurately identify a Japanese Beetle from a June bug and even see some of their other not-too-obvious similarities.

Comparing June Bugs and Japanese Beetles 

June bugs are bigger than Japanese beetles.


June BugJapanese Beetle
Length 12-25mm (0.5 – 1 in)10-15mm (0.4 – 0.6 in)
Color Reddish-brown, black. Green and copper, with bronze wings 
Activity Time Nocturnal i.e. active at night Diurnal i.e. active during the day 
Reproduction (eggs laid)50-200 eggs 40-60 eggs 
Destructiveness Less destructive as adults Equally destructive as larvae and adults 
Scientific Classification Genus PhyllophagaGenus Popillia 
Number of Species 900+One 

Key Differences Between a June Bug and a Japanese Beetle

The most obvious difference between a June bug and a Japanese beetle is in their size. The Japanese beetle is considerably smaller than the June bug. The Japanese beetle has an average size of 10-12 mm (0.4 – 0.5 in), and the largest one can reach 15 mm (0.6 in). On the other hand, the June bug has a size of about 12-25 mm (0.5 to 1 in). This means that the largest June bug is almost two times bigger than the largest Japanese beetle. 

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Several other key differences between the two insects are described below.

June Bug Vs Japanese Beetle: Color 

June bugs are usually a single color of either reddish-brown or black.

©Sean Harris acts238/Shutterstock.com

Japanese beetles are multicolored while June beetles are usually a single color of either reddish-brown or black. A Japanese beetle is usually a mix of green and copper with bronze wing coverings. They also possess white hair on their sides. 

June Bug Vs Japanese Beetle: Activity Time 

Japanese beetles are active during the day, therefore they are diurnal creatures. On the other hand, June bugs are mostly nocturnal insects, which means that they are most active at night. It is possible to see June bugs fly around during the day especially when they newly emerge as adults. However, they are most active at night and are attracted by lights from residential houses and gardens. At night, Japanese beetles go to their underground nests. 

June Bug vs Japanese Beetle: Reproduction 

Japanese beetle walking on a leaf
Japanese beetles lay 40-60 eggs per season.


A female Japanese beetle will lay anywhere between 40-60 eggs per season. However, June bugs are far more reproductive with the ability to lay 50-200 eggs per season. Mating for both insects occurs during their active period and they usually alternate mating and eating at extremely high levels.

Furthermore, the gestation period for Japanese beetles is one to two weeks, and then the egg hatches. However, for June bugs, the typical gestation period is two and a half weeks to 4 weeks. 

June Bugs vs Japanese Beetles: Destructiveness 

This particular distinction may be most significant to farmers and gardeners. While both insects can be harmful to crops and plants, the adult Japanese beetle is far more destructive than the June bug. This is because the adult June bug doesn’t eat enough of a tree, plant, or flower to cause massive destruction. Rather, it is during the larva stage that the June bug becomes an obstacle and pest to farmers since it attacks the roots of vegetation, thus killing it or impeding proper growth. 

On the other hand, the adult Japanese beetle will eat any foliage that is nearby and may even feast on fruits as well. Both at the larva and adult stages, the Japanese beetle is considered a major pest and can be incredibly destructive.  

June Bug vs Japanese Beetle: Number of Species 

Japanese beetle on leaf
There’s just one species of Japanese beetle while there are over 900 species of June bugs.


The Japanese beetle has just one species while the June bug possesses over 900 species. Even though both insects are of the same family, there is only one species of the Japanese beetle that gardeners and farmers have to deal with. The June bug however comes in several species, each with its own preference and features.

June Bugs vs Japanese Beetles: Scientific Classification 

Japanese beetles and June bugs may be classified in the same order and family, but they have different genera and scientific names. Japanese beetles belong to the genus Popillia and their scientific name is Popillia Japonica. June bugs, on the other hand, belong to the genus Phyllophaga where there are over 900 species of the insect.  

Are there any Similarities between June Bugs and Japanese Beetles? 

Despite all the differences mentioned above, there are also a good number of similarities between these two insects.  One very interesting similarity between June bugs and Japanese beetles is that they are both edible to human beings. 

Yes, humans can eat these insects and can even expect to gain some nutrients from them. For example, Japanese beetles are rich in protein and they are good sources of Zinc and B12. These insects are edible as larva as well as adults. In fact, generally speaking, and especially for June bugs, people testify that the larva stage is tastier than the adult stage. You can harvest the larvae of these insects from the ground, and you can easily catch the adult June bugs when they get attracted to residential light. Some communities consume June bugs as a traditional food such as the Bear River community in northwestern Califonia

Other similarities between June bugs and Japanese beetles include: 

  • They are both harmless to human beings: Japanese beetles and June bugs pose no threats to humans in any way. They do not bite, sting, or spread diseases. Their only danger is to plants and flowers. 
  • They are dangerous to plants and crops: Both insects will do serious damage to crops and plants in their vicinity because these are their primary sources of food. At the larva stage, the June bug is quite as destructive as the Japanese beetle .
  • They have similar predators: They are both prey to predators like birds, raccoons, moles, and any animal that generally eats beetles and bugs. 
  • They belong to the same scientific family and order: Apart from both being insects, June bugs and Japanese beetles belong to the same scientific family and order – Order Coleoptera and Family Scarabaeidae.

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