Japanese beetles
Japanese beetle. Photo credit: David Cappaert,Bugwood.org, CC BY-NC 3.0 US
How do I know if I have Japanese beetles in my garden, and what’s the difference between them and other beetle friends that I may find? Who do I call if I suspect Japanese beetles in my landscape?
Japanese beetles (Popillia japonica) are common in the Eastern part of the US, but not so in New Mexico. In fact, the New Mexico Department of Agriculture (NMDA) works hard to ensure this destructive agricultural pest does not establish itself in New Mexico. In our increasingly globalized society, there is a real threat that it will be accidentally introduced into the New Mexico landscape. Given all of its commonly found lookalikes, we want to know what to look for. With the right knowledge, even someone without much experience can learn to identify this important pest and help keep New Mexico safe from infestation.
What does the Japanese beetle do in the landscape that makes it such a menace? It all starts with the larvae, which hatch in the summer and feed on tender plant roots in the soil. Plants in the grass family (Poaceae) are especially attractive, as this beetle likes to lay its eggs in grassy areas near its favorite host plants. This feeding causes wilting and eventual plant death. Adults emerge from the soil the following summer to chew on leaves, leaving behind a skeletonized appearance. Many beetles chew on leaves and plant roots with little effect on overall plant health, but Japanese beetles feed voraciously on over 300 species of valuable plants, including crops (such as grape and soybean), trees (such as maple and apple), and ornamentals (such as rose and crepe myrtle). By comparison, the cucumber beetle (another green garden pest) focuses its feeding on plants from only a few families.
Not a Japanese beetle! This is a spotted cucumber beetle (Diabrotica undecimpunctata). Photo credit: Susan Ellis,Bugwood.org, CC BY-NC 3.0 US
Japanese beetles in the U.S. lack the natural enemies present in their native environment, and can infest home gardens, farms, arroyos, parks, and irrigated cropland. Infested landscapes may need to undergo treatment or be replaced altogether.
The worst part is how easy it is to accidentally spread this pest. Japanese beetles are easily transported in the soil of nursery plants and cut sod. Plants that move from one state to another on airplanes and cargo trucks may introduce hitchhiking Japanese beetles to new areas. Thankfully, NMDA places hundreds of Japanese beetle traps all around the state, to hopefully find beetles before an accidental introduction can become an outright infestation.
Japanese beetle trap. Photo credit: Bethany Abrahamson.
You too can keep an eye out for Japanese beetles in your landscape. However, before we go overboard thinking every green bug is a horrible garden invader, we need to know what to look for. This critter is easy to identify once you know its key characteristics. The body shape of an adult Japanese beetle is typical of scarabs, such as chafer beetles or June beetles: prominent wing covers, a large shoulder plate (pronotum), and finger-like projections on the antennae. They are distinguished from other similar beetles by their size, which is about 1/3-inch long, combined with their distinctive coloration of metallic emerald on the body and coppery-brown on the wing covers (elytra)—but not by these traits alone. Also look for a line of white hair tufts found on either side of the body. If there are no tufts, it’s not a Japanese beetle.
Japanese beetle larva, adults, and pupae. Photo credit: Whitney Cranshaw, Colorado State University, Bugwood.org, CC BY-NC 3.0US
Larvae may be anywhere from 1/16th of an inch to 1 and 1/8th of an inch long, depending on the age, and are C-shaped like other scarab beetles. These are difficult to distinguish from other common white grubs such as figeater beetles, and accurate identification must be made with the help of a microscope. Experts can study a larva’s hair arrangement to determine the species.
There are several other common beetles that may be mistaken for the Japanese beetle by an untrained eye. Here are a few of them:
Not a Japanese beetle! This is a figeater beetle. Photo credit: Emmy Engasser, Hawaiian Scarab ID, USDA APHIS PPQ, Bugwood.org, CCBY-NC 3.0 US
Figeater beetle (Cotinis mutabilis)- This common beetle can often be seen flying around orchards in late summer. It is much larger than a Japanese beetle, up to 1-1/3 inches in length. If these beetles are bugging you in your garden, cleaning up excess organic matter such as fallen fruit from your fruit frees, and protecting your compost heap using screen or tarp, can help control populations.
Not a Japanese beetle! This is a false Japanese beetle. Photo credit: Whitney Cranshaw, Colorado State University, Bugwood.org, CCBY-NC 3.0 US
False Japanese beetle (Strigoderma arbicola)- Also called spring rose beetles, these beetles are associated with a variety of native and introduced plants, and their grubs may attack plants in sandy soil, hence their other common name, ‘sand chafer’. They can be considered a pest in some situations, but damage is generally minimal. False Japanese beetles are very similar in size and shape to the true Japanese beetle and may be found in Japanese beetle traps. However, their coloration is brown and black compared to the green and copper color of true Japanese beetles. These lookalikes are also missing the white tufts on the sides of their bodies.
Not a Japanese beetle! This is a hairy bear beetle. Photo credit: Jbjensen1 via Wikimedia Commons, CC BY 4.0.
Hairy bear beetle (Paracotalpa spp.)- While these beetles have similar coloration to Japanese beetles, they are somewhat larger and are covered in light hairs. This species is found in juniper woodlands.
Invasive pests are always a little worrying, but with everyone’s help we stand a good chance of keeping this pest at bay! If you suspect you have Japanese beetles in your landscape, please call the New Mexico Department of Agriculture at (575) 646-3207, or send a photo to your local Cooperative Extension Agent.
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You can learn more about Japanese beetles and how to keep them out of New Mexico at this month’s Ready, Set GROW! Webinar, Wednesday 10/15 at 3:00 PM!
Check out these helpful resources on Japanese beetles and their lookalikes!
Japanese beetle:
“Japanese beetle” by Jamba Gyeltshen, Amanda Hodges, and Clayton Bania, University of Florida IFAS Extension publication #EENY350 (2019).
Figeater beetle:
“Green fruit beetle” by UC IPM Home and Landscape (2025).
False Japanese beetle:
“False Japanese Beetles Present Again This Year” by Donald Lewis, Iowa State University Extension and Outreach Yard and Garden News (2015).
“Spring Rose Beetle” by James Baker, NC State Extension PDIC Fact Sheets (2024).
Hairy bear beetle:
“Species Paracotalpa granicollis” on Bugguide.net (2025).
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