5 Insects That Start with J: From Jerusalem Crickets to Jar Flies
October 25, 2026
Insects that start with J include a cricket that is not really a cricket, a “bug” that is actually a beetle, and a “fly” that is neither. Common names in North America are loose, and the J list is full of them.
This article covers five J insects that Americans actually meet: on porch lights in June, on rose bushes in July, and in the trees on a humid summer evening. Each section explains what the insect is, where it lives, and how to tell it apart from its look-alikes.
The wider J list is long. The InsectIdentification.org database alone catalogs 23 J entries, including butterflies such as the Juniper Hairstreak and Juvenal’s Duskywing. You can browse that catalog at InsectIdentification.org. If you like letter-by-letter lists, the roundup of insects that start with H is a good companion read.
| Insect | What It Really Is | Typical U.S. Sighting |
|---|---|---|
| Jerusalem Cricket | Large, flightless, ground-dwelling insect | Western states, mostly at night |
| June Beetle | Reddish-brown scarab beetle | Porch lights, late spring and early summer |
| June Bug | Often a green scarab beetle | Eastern and southern lawns and fruit trees |
| Japanese Beetle | Invasive metallic green and copper scarab | Gardens and roses from late June |
| Jar Fly | Regional nickname for a cicada | Southern and Appalachian summer trees |
1. Jerusalem Cricket
The Jerusalem cricket is a good place to start because almost everything in its name is misleading. It is not from Jerusalem, and it is not a true cricket. It is a big, wingless insect found throughout western North America.
Most people in the West know it by a nickname. “Potato bug” is common, and “niño de la tierra” (child of the earth) comes from the Spanish-speaking Southwest. The pale, round-headed face and glossy, striped abdomen give it an oddly human look that stops people mid-step in a garden.
These insects spend most of their lives underground. They come to the surface at night, often after irrigation or rain, which is when homeowners find them on patios and walkways. They can pinch or bite if handled roughly, so scoop one up with a cup and a piece of paper instead of bare fingers.
Jerusalem crickets also matter in their habitats. They help break down organic matter in desert soils. They also feed birds, reptiles, and small mammals. The genus Stenopelmatus includes several western species that look much alike, which is why identification usually stops at “Jerusalem cricket.”
Curious about other bugs that go by confusing names? The list of insects that start with E has a few more oddballs.
2. June Beetle
June beetles are the thumping, clumsy fliers that smack into screen doors on warm nights. They belong to the genus Phyllophaga, a name that means “leaf eater” in Greek. They sit in the scarab family, which has more than 30,000 species, and about 200 of those are North American June beetles.
Texas A&M’s field guide to common Texas insects describes the adults as ½ to 5/8 inches long and reddish brown. Their grubs are the lawn-damaging stage. The grubs are C-shaped, up to 1 inch long, with cream-colored bodies and brown head capsules.
Timing depends on where you live. Adults begin to emerge in spring, and peak flights come in mid to late June in central Texas. In the northern states the flights tend to run later, which is why the same beetle is also called a May beetle in some places.
Light is the main way people notice them. June beetles are nocturnal and are attracted to light, which is why they hit windows. Switching to warm-toned or yellow bulbs on your porch reduces the crowd.
For more on the U.S. species and their natural enemies, see Texas A&M’s June beetle page. You can also browse our animals that start with S list to see how other creatures pick up regional names.
3. June Bug
“June bug” is a nickname, not a species. In much of the eastern and southern U.S., the insect people mean is the green June beetle (Cotinis nitida). It is bigger and more colorful than its brown cousins, with a metallic green back.
According to Safer Brand’s identification guide, the green June beetle has a green body up to an inch long, and its primary range runs from Maine to Georgia. It flies low and slow in daylight, buzzing across lawns like a small helicopter.
There is no need to worry about biting. June bugs do not bite people, though the spines on their legs can deliver a slight pinch when they land on you. Kids who catch them on a string are usually more bothered than the bug is.
Common Mistake: Treating every “June bug” as the same pest. The adult, the grub, and the species all call for different responses, so identify the beetle before you buy any treatment.
Below ground, the grubs have plenty of enemies. Moles eat large numbers of larvae. That is one reason a lawn with fresh mole tunnels may have a grub problem underneath it. If you enjoy tracing common names through the animal kingdom, our list of animals that start with D is another fun detour.
4. Japanese Beetle
The Japanese beetle (Popillia japonica) is the one J insect that most American gardeners know by name, and few welcome it. It was first found in the United States in 1916 after being accidentally introduced into New Jersey. Before then, it was restricted to Japan, where it is not a major pest.
Identification is easy. The University of Wisconsin-Madison Division of Extension describes a shiny, metallic-green beetle slightly less than ½ inch long, with coppery-brown wing covers. Small patches of white hairs line the edges of its back. Unlike many beetles called June bugs, it feeds in daylight.
What Japanese Beetles Damage
The adults eat leaves, flowers, and fruit, and the grubs eat roots. The University of Minnesota Extension says adults feed on more than 300 plant species, while the grubs chew turfgrass roots, causing lawns to brown and die. Roses, birch, crabapple, grapes, and basil are among the preferred hosts.
Important Note: Plant-count estimates differ by source. Minnesota Extension says more than 300 species, while Wisconsin Extension says over 350. Either way, the host list is very long.
When to Watch For Them
Timing is predictable. Adults emerge from the ground in late June or early July and feed mainly in July and August, with some active into September. In Connecticut, the beetle arrives about the Fourth of July every year.
The University of Minnesota Extension also notes that a parasitic fly called the winsome fly lays eggs on adult beetles, which gives gardeners a natural ally.
Pro Tip: Hand-pick beetles into soapy water in the morning instead of spraying broad-spectrum insecticides. Gardeners in the Upper Midwest who plant for the Minnesota monarch butterfly and other common butterflies in Minnesota will protect pollinators this way, since sprays also kill the butterfly species native to Minnesota that visit the same blooms.
After you handle the beetles, you might want to check the animals that start with P list for the predators and pollinators that share your garden.
5. Jar Fly
The jar fly is a regional nickname for the cicada, an insect that is not a fly at all. Word lists such as ScattergoriesOnline.net describe it as a regional U.S. name for the cicada. You are most likely to hear “jarfly” in the South and in Appalachia, where the name is usually tied to the jarring, droning song of summer.
Cicadas live most of their lives underground as nymphs, feeding on tree roots. When it is time to emerge, they climb a trunk, split their shells, and leave papery brown husks behind. The adults then sing from the treetops, and only males make the sound.
Two groups show up in American yards. Annual cicadas appear every summer, while periodical cicadas such as the 17-year cicada (Magicicada septendecim) emerge in synchronized broods after long, predictable gaps. The two are often confused with locusts, but cicadas do not swarm crops the way locusts do.
Cicadas do not bite or sting. Their large, sudden presence is the main nuisance, along with the loud chorus on hot afternoons.
Together, these five insects show how much common names can mislead. A Jerusalem cricket is a ground-dwelling oddity of the West, June beetles and June bugs are scarabs that give lawns and porch lights their summer drama, the Japanese beetle is an import that keeps gardeners busy, and the jar fly is a cicada under a Southern alias. Check the region, the season, and the body shape, and the right name usually follows. For more letter-by-letter animal lists, try animals that start with T.