17 Types of Beetles in Idaho: A Field Guide to the Gem State’s Most Common Species
September 11, 2026
From the wheat fields of the Palouse to the lodgepole forests of the Sawtooths, Idaho’s landscapes support an enormous range of beetles. Anyone trying to sort out the types of beetles in Idaho quickly discovers that the state’s insect life is far more varied than a quick glance at a garden pest guide would suggest.
According to the insect identification database, there are a total of 120 different types of beetles found in the state of Idaho, while a separate regional catalog places the figure even higher. That range exists because Idaho’s habitats stretch from arid steppe to dense conifer stands, and each zone hosts its own beetle community. Readers curious about how that stacks up against the rest of the order can check out this breakdown of how many types of beetles exist worldwide, or compare notes with Idaho’s other buzzing residents in this guide to types of bees in Idaho.
Below is a quick snapshot of the 17 species covered in this guide before diving into the details of each one.
| Beetle | Family | Typical Size | Where to Find It in Idaho |
|---|---|---|---|
| Ten-lined June Beetle | Scarabaeidae | 0.75-1.2 in | Gardens, roses, orchards |
| Ponderous Borer Beetle | Cerambycidae | Up to 2.5 in | Dead conifers, forest edges |
| Western Pine Beetle | Curculionidae (bark beetle) | 0.1-0.2 in | Ponderosa pine bark |
| Japanese Beetle | Scarabaeidae | 0.4 in | Ornamental plants, crops |
| Banded Elm Bark Beetle | Curculionidae | 0.1 in | Elm trees |
| Smaller European Elm Bark Beetle | Curculionidae | 0.08-0.12 in | Elm trees |
| Squash Lady Beetle | Coccinellidae | 0.3 in | Squash and cucurbit gardens |
| White-spotted Sawyer Beetle | Cerambycidae | 0.5-1 in | Pine, spruce, fir forests |
| Flower Longhorn Beetle | Cerambycidae | 0.3-0.7 in | Wildflowers, meadows |
| Dung Beetle | Scarabaeidae/Geotrupidae | 0.2-0.8 in | Pastures, rangeland |
| Predaceous Diving Beetle | Dytiscidae | 0.4-1.5 in | Ponds, slow streams |
| Ladybug | Coccinellidae | 0.1-0.3 in | Gardens, crop fields |
| Ground Beetle | Carabidae | 0.2-1 in | Soil, leaf litter |
| Longhorn Beetle | Cerambycidae | Varies widely | Forests, dead wood |
| Blister Beetle | Meloidae | 0.3-1 in | Rangeland, alfalfa fields |
| Click Beetle | Elateridae | 0.3-1.5 in | Gardens, fields, woodlands |
| June Bug | Scarabaeidae | 0.5-1 in | Lawns, porch lights |
1. Ten-lined June Beetle
The ten-lined June beetle (Polyphylla decemlineata) is one of the most recognizable beetles in the state, named for the ten pale stripes running down its gray-brown wing covers. Regional identification resources rank it among Idaho’s largest and most common beetles, alongside the ponderous borer, western pine beetle, and Japanese beetle.
Two of the biggest beetles found in north Idaho are the ten-lined June beetle found in roses, strawberries, and potatoes, making it a familiar sight to home gardeners. Its larvae live underground for one to two years, feeding on plant roots before emerging as heavy-bodied adults that buzz loudly in flight.
2. Ponderous Borer Beetle
Few Idaho beetles inspire more double-takes than the ponderous borer (Trichocnemis spiculatus), a long-horned species so large that an Oregon State University Extension entomologist described it as a long-horned beetle native to the region that people don’t see all that often, and feel lucky when they do.
Ponderous borer larvae, which can measure almost three inches long, tunnel through the sapwood and heartwood of their dead or dying host trees, hastening their decomposition and the fall of dead stands. Loggers have long called them “timber worms,” and according to legend, the mandibles and boring action of the beetle larvae gave a logger the idea for the modern chainsaw. Adults are drawn to porch lights and lake shores on warm summer nights, which is often how people encounter this spectacularly large native beetle for the first time.
Pro Tip: Ponderous borers look intimidating but rarely attack living trees. The adults are not inclined to bite, though handling one roughly can earn you a startling pinch from its powerful jaws, so it’s best to admire this beetle from a respectful distance.
3. Western Pine Beetle
Unlike the ponderous borer, the western pine beetle (Dendroctonus brevicomis) is genuinely dangerous to trees. This bark beetle infests the boles of ponderosa pine trees larger than six inches in diameter, and outbreaks tend to follow drought years when trees are already stressed.
Spotting an infestation takes a trained eye, since the beetle itself is tiny. Adults are dark brown and only 3 to 5 millimeters long, but they cause small globules of pitch called pitch tubes to form on the tree bole at points of entry, and these tubes are typically white to reddish brown and about a quarter to a half inch in diameter. The flaking of ponderosa bark by woodpeckers feeding on these insects is a common diagnostic clue used to confirm an attack. Foresters tracking outbreaks across the region also rely on the Oregon Department of Forestry’s fact sheet on this species for management guidance.
4. Japanese Beetle
The Japanese beetle (Popillia japonica) is a metallic green and copper invader that has become a persistent headache for gardeners. The ten-lined June beetle is primarily found in the southeastern part of Idaho, while the Japanese beetle has a wider distribution across the state, making it one of the more widely encountered types of beetles in Idaho.
This harmful pest has reportedly been spotted in at least two counties of Idaho, where it causes damage to crops and gardens. Agricultural impacts extend beyond ornamentals, too, since Japanese beetles target ornamental plants while other beetle pests like wireworms damage Idaho’s potato fields. Gardeners in states with longer-established populations, such as those detailed in this guide to beetles found in Ohio, offer a preview of how aggressively this species can spread once established, which explains why Idaho agencies monitor new sightings closely.
5. Banded Elm Bark Beetle
The banded elm bark beetle (Scolytus schevyrewi) is a small, reddish-brown invader that arrived in North America from Asia and has since spread through much of the western United States. This species, along with the European elm bark beetle, feeds on elms and vectors the Dutch elm disease fungus, Ophiostoma novo-ulmi, a pathogen that has devastated elm populations across the continent.
In its native habitat in Asia, the banded elm bark beetle reportedly also feeds on certain non-elm tree species, which has raised concerns among foresters about its adaptability. States with mature elm plantings, including Minnesota’s documented beetle species, have tracked similar bark beetle pressure on urban elm canopies for decades.
Important Note: Bark beetle identification often requires examining gallery patterns under the bark rather than the beetle itself, since many species look nearly identical to the naked eye. If you suspect Dutch elm disease on a property, contacting a local extension office for confirmation is the most reliable path forward.
6. Smaller European Elm Bark Beetle
As its name suggests, the smaller European elm bark beetle (Scolytus multistriatus) is the more diminutive cousin discussed above. Taxonomic records list this species at just 1.9 to 3.1 millimeters long, small enough that most people never notice one even when it’s crawling across bark right in front of them.
Despite its size, this beetle carries the same Dutch elm disease fungus as its banded relative, which is why the two species are frequently discussed together in bark beetle management literature. Communities that once relied heavily on American elm street trees, such as those profiled in this look at Massachusetts beetle species, learned the hard way how quickly this pairing of tiny beetle and lethal fungus can reshape an urban forest.
7. Squash Lady Beetle
Not every lady beetle in the garden is a friend to farmers. The squash lady beetle belongs to the family Coccinellidae but, unlike most of its relatives, feeds directly on squash, pumpkin, and other cucurbit foliage rather than on aphids.
Its yellowish-tan body with black spots can cause confusion among gardeners expecting a beneficial ladybug. Squash growers in states with heavier cucurbit production, including those covered in this guide to Kansas beetle species, watch for the lacy, skeletonized leaf damage that gives this beetle’s presence away well before the insect itself is spotted.
Common Mistake: Don’t assume every spotted beetle on your squash plants is helping control pests. Squash lady beetles feed on the plants themselves, and their damage pattern (a distinctive skeletonized leaf) is the easiest way to tell them apart from beneficial lady beetles.
8. White-spotted Sawyer Beetle
The white-spotted sawyer beetle (Monochamus scutellatus) is a long-horned wood-borer with a single pale spot between its wing covers, giving it its common name. This species poses a threat to pine, spruce, and fir trees and is frequently mistaken for the destructive Asian longhorned beetle because of its size and dark, mottled coloring.
Unlike true invasive longhorns, the white-spotted sawyer is native and typically targets trees that are already dead, dying, or recently harvested rather than healthy stands. Forest managers in timber-heavy states, such as those referenced in this overview of Virginia’s beetle populations, note that its larvae play a useful role in breaking down downed timber after fires or windstorms.
9. Flower Longhorn Beetle
Flower longhorn beetles are a subgroup of the longhorn family that spend their adult lives visiting blossoms rather than boring into wood. Idaho’s beetle records include several documented flower longhorn species, such as Strangalia emarginata and Strangalia luteicornis, both of which show the slender bodies and long legs typical of the group.
These beetles are important pollinators, often seen crawling across wildflowers and garden blooms in search of nectar and pollen. Gardens designed to attract pollinators, similar to those discussed in this guide to South Carolina’s beetle diversity, tend to see flower longhorns show up alongside bees and flies during peak bloom season, and their movements can be cross-referenced on identification databases like BeetleIdentification.org’s Idaho listings.
10. Dung Beetle
Dung beetles are among the most ecologically useful insects in Idaho’s rangeland ecosystems, breaking down animal waste and recycling nutrients back into the soil. Regional insect databases document species such as Dichotomius sp. among Idaho’s dung beetle fauna, a genus known for its sturdy, rounded body built for burrowing.
Cattle country across the American West depends heavily on these insects, since a single active dung beetle population can bury manure far faster than it would decompose on its own. Ranching regions covered in this profile of Missouri’s beetle species report similar benefits, including reduced fly breeding grounds and faster nutrient cycling in pastures.
11. Predaceous Diving Beetle
Ponds, irrigation ditches, and slow-moving streams across Idaho host predaceous diving beetles, aquatic hunters built for life underwater. Idaho’s documented species in this group include Acilius mediatus, part of the family Dytiscidae, which uses paddle-shaped hind legs to chase down mosquito larvae, small fish, and other aquatic prey.
These beetles trap air beneath their wing covers to breathe while submerged, surfacing periodically to replenish their supply. Wetland habitats similar to those found in Canada’s beetle-rich boreal regions support especially dense diving beetle populations, and the full range of species recorded across Idaho can be browsed on InsectIdentification.org’s Idaho beetle listing.
12. Ladybug
Ladybugs, or lady beetles, rank among the most beloved insects in any garden, prized for devouring aphids and other soft-bodied pests. Common Idaho beetles include ladybugs alongside ground beetles, longhorn beetles, and blister beetles, and among the state’s documented species is the Convergent Lady Beetle, named for the converging white lines on its otherwise red, black-spotted wing covers.
Gardeners often release purchased ladybugs to control aphid outbreaks, though native populations typically handle the job just fine on their own given time. Vegetable growers in regions covered by this guide to New Jersey’s beetle species report similar reliance on native lady beetle populations for natural pest suppression.
Key Insight: A true ladybug and a squash lady beetle can look deceptively similar at a glance. Checking the host plant is often faster than counting spots: aphid-covered plants attract beneficial ladybugs, while skeletonized squash leaves point to the plant-eating impostor.
13. Ground Beetle
Ground beetles make up one of the largest and most varied beetle families found across Idaho, and most species share a predatory lifestyle spent hunting other insects at night. Idaho hosts diverse beetle species including ground beetles, metallic wood-borers, ladybugs, click beetles, and June bugs, reflecting just how central this family is to the state’s insect community.
Within this group, tiger beetles stand out for their speed and predatory precision. Idaho is home to 16 species of tiger beetles, including Cicindela depressula and Cicindela parowana, both of which hunt smaller insects across open, sandy ground. Readers interested in how coloration varies across this family may enjoy this breakdown of common black beetle species, since many ground beetles share a similar dark, glossy exoskeleton.
14. Longhorn Beetle
Longhorn beetles, named for their exceptionally long antennae, form one of the most diverse beetle families in Idaho’s forests. A study on Idaho’s longhorned beetles listed 134 species, including Batyle ignicollis, Callidium antennatum, and Megacyllene robiniae, many of which help break down dead wood in forest ecosystems, according to research published by Rice, Merickel, and MacRae in 2017.
This family includes both the ponderous borer and white-spotted sawyer covered earlier, along with dozens of smaller, less conspicuous species that rarely draw attention despite their abundance. Forested regions profiled in this guide to California’s beetle diversity report a similarly rich longhorn beetle community, particularly in areas with abundant dead or downed timber. Details on individual species can be cross-checked at the Big Foot Pest Control overview of Idaho’s beetle populations.
15. Blister Beetle
Blister beetles get their unusual name from a defensive chemical they secrete when threatened, which can cause skin irritation or blistering on contact. These beetles rank among Idaho’s common types, alongside ladybugs, ground beetles, and longhorn beetles, and they’re most often spotted in rangeland and alfalfa fields during summer months.
Livestock owners pay particular attention to blister beetles because they can contaminate hay if accidentally baled with alfalfa, posing a risk to horses that ingest the toxin. Arid rangeland habitats similar to those described in this guide to Arizona’s beetle species tend to host especially dense blister beetle populations during hot, dry summers.
16. Click Beetle
Click beetles earn their name from a spring-loaded mechanism in their thorax that lets them snap upright with an audible click if they land on their backs. This family is part of the diverse beetle community documented across Idaho, alongside ground beetles, metallic wood-borers, ladybugs, and June bugs, and their larvae, known as wireworms, can damage root crops in agricultural fields.
Adult click beetles are generally harmless to gardens and are more often noticed for their acrobatic escape trick than for any damage they cause. Farming regions covered in this guide to Texas beetle species report similar wireworm concerns in row crops, underscoring how the larval stage matters more than the adult when it comes to agricultural impact.
17. June Bug
June bugs, often used as a catch-all term for various Scarabaeidae species that emerge in late spring and early summer, are famous for bumbling into porch lights and window screens on warm nights. Idaho’s beetle fauna is often summarized as ranging from ladybugs to june beetles, capturing just how broad this common nickname can be.
Most June bugs belong to the genus Phyllophaga, distinct from the ten-lined June beetle covered earlier despite the overlapping name. Homeowners dealing with lawn grub damage in states like those covered in this guide to Tennessee’s beetle species often trace the problem back to June bug larvae feeding on grass roots underground, a pattern well documented by regional pest resources including the Candor Pest Control overview of Idaho’s beetle populations.
Idaho’s beetle fauna reflects the state’s remarkable range of habitats, from ponderosa pine forests plagued by bark beetles to irrigation canals humming with diving beetles and pastures full of dung beetles. Learning to tell these 17 species apart takes some practice, but each one plays a distinct role in the ecosystems that make up the Gem State, whether that’s recycling dead wood, pollinating wildflowers, or keeping aphid populations in check.