Green Bug Identification: 8 Common Green Insects

Most green bugs fall into two groups by size: small, soft insects crowded on plants, which are usually aphids, leafhoppers or young stink bugs, and large green insects, which are usually katydids, praying mantises, adult stink bugs or metallic green beetles. Insectidentification.org lists 130 green insects, so size and one or two key marks are the fastest way to narrow it down.

• Under about 1/8 inch and in groups: look at the rear end for two small tubes (aphids) and at how it moves (leafhoppers jump).
• Around 1/2 inch and shield-shaped: a stink bug. Look for the large triangle on the back.
• An inch or more, with long legs: katydid or mantis. Check the antennae and front legs.
• Hard, shiny and metallic: a beetle.

• Aphids: soft, pear-shaped bodies with long legs and antennae, in green, yellow, brown, red or black depending on species. The pair of tubes (cornicles) pointing backward from the rear end separates aphids from every other insect. They leave sticky honeydew that often turns black with sooty mould, and ants tend them (UC IPM). See aphids.
• Leafhoppers: small sap-feeders with hind legs made for jumping and a row of movable spines along each hind shin. With at least 20,000 described species, this is the second-largest family of true bugs, and some, such as the potato leafhopper and the glassy-winged sharpshooter, are serious crop pests that spread plant diseases (Wikipedia).
• Green lacewings: adults about 3/4 inch from head to wing tip, green with golden eyes and four clear wings held like a roof over the body. Their eggs sit on the ends of silk stalks, and the larvae, which look like tiny alligators, eat aphids, mealybugs, scales and thrips (UC IPM). See lacewings.
• Young stink bugs: late-stage nymphs of the southern green stink bug are green; the earliest stages are pale yellow (UC IPM).

• Katydids: leaf-shaped and leaf-coloured, with thread-like antennae that can be longer than the body, while grasshoppers always have short, thicker antennae. They range from 5 mm to 130 mm, and the males sing by rubbing parts of their front wings together (Wikipedia). See grasshoppers, crickets and katydids.
• Praying mantises: triangular head and raised, spiny front legs held as if praying. The Chinese mantis reaches just over 11 cm (Wikipedia). See praying mantis identification.
• Southern green stink bug: about 1/2 inch, bright green, shield-shaped, with a large triangle (the scutellum) covering the middle of the back; it can release a foul-smelling fluid when disturbed. The consperse stink bug is also about 1/2 inch, greyish brown to green, with black-speckled legs (UC IPM).
• Japanese beetle: 1/3 to 1/2 inch, metallic green head and thorax with copper-brown wing covers, five white hair tufts along each side and two at the tip. Adults feed mainly in July and August (University of Minnesota Extension).
• Green June beetle: 15 to 22 mm, dull metallic green with gold sides, active in daylight from June (Wikipedia).

Mostly neither. Most katydids eat leaves, flowers, bark and seeds, and many species are purely predatory, feeding on other insects and snails. Wikipedia notes that their population densities are usually low, so a large economic impact is rare. Large katydids can give a painful bite or pinch if handled but seldom break the skin, so pick them up with care or not at all.

• Plant pests: aphids (honeydew, sooty mould), leafhoppers (sap feeding and plant diseases), stink bugs (blemishes and dark pinpricks on fruit such as tomatoes) and Japanese beetles, which skeletonise leaves so only a lacy network of veins is left (UC IPM; Wikipedia; University of Minnesota Extension).
• Helpers: green lacewings, whose larvae eat aphids and other soft pests (UC IPM).
• Mixed: praying mantises eat pests but also pollinators and other beneficial insects; see the mantis page.
• Mostly harmless: katydids, as above.

Before spraying anything green, check whether it is a lacewing or its alligator-shaped larva; UC IPM lists lacewings among the main natural enemies of aphids.

Green insects blend into leaves, so move the leaf or the bug against a plain background if you can. Take one photo from above and one from the side, with a coin for scale. For a small bug on a stem, get the rear end in focus (aphid tubes) and the hind legs (leafhopper spines); for a large one, include the full antennae. InsectLens names the insect from the photo.

Research and drafting for this page used AI assistance. Every figure, date and quotation was then checked line by line against the sources listed at the bottom of the page, each of which was opened while writing. Nothing here is a diagnosis. If a bite, sting or contact with an insect is followed by trouble breathing, swelling of the face or throat, spreading redness, fever or any symptom that worries you, get medical care; in the United States Poison Help (1-800-222-1222) is free and open 24 hours a day.