Beetle Larvae Identification: 9 Types by Shape

You identify beetle larvae by their legs and their shape: they have three pairs of jointed legs just behind the head, or no legs at all, and never the fleshy prolegs that caterpillars have along the abdomen (UC IPM). Then match the body shape and where you found it to the types below, which follow the University of Kentucky's insect larva key.

Three questions sort almost any larva:

• Fleshy prolegs on the abdomen? Yes, on five or fewer segments: a caterpillar. Yes, on six or more: a sawfly larva (UC IPM). No: keep going.
• Three pairs of jointed legs behind the head? Yes: a beetle larva (or a lacewing larva, which is also a long-legged predator). No: go to the next question.
• A visible head? Yes, with no legs: likely a weevil or wood-boring beetle larva. No head visible: most likely a fly maggot (University of Kentucky).

With legs:

• White grubs (scarab beetles): soft, white, C-shaped, with short thick legs and a box-shaped head; in soil, decaying matter and rotting logs (University of Kentucky). See grubs.
• Wireworms (click beetles): hard, cylindrical bodies; in soil feeding on seeds and roots, or in decaying wood (University of Kentucky).
• Mealworms (darkling beetles): hard, tan to brown, up to about 1.25 inches; the larva of the yellow mealworm beetle, Tenebrio molitor (Wikipedia). Larvae start white and turn brown after the second larval stage (Wikipedia).
• Rootworm larvae: short, thick legs; in soil, feeding on plant roots (University of Kentucky).
• Leaf beetle larvae: look like caterpillars without the fleshy abdominal legs and feed in the open on leaves, like the Colorado potato beetle larva (University of Kentucky; UC IPM).
• Lady beetle and ground beetle larvae: long legs, streamlined and often pointed bodies, flat heads with forward-pointing jaws; these are predators (University of Kentucky). Ladybird larvae are elongated with square heads and covered in hairs or bristles (Wikipedia).
• Carpet beetle larvae: small, hairy and carrot-shaped, 1/4 inch or less, in closets and on wool (University of Maryland Extension).

Without legs:

• Weevil grubs: flat underneath and rounded on top, giving a humpbacked look; inside seeds, nuts, plant tips or with roots (University of Kentucky).
• Wood borers: flatheaded borers have a distinctly wide area behind the head and a long, soft white body; roundheaded borers look similar without the wide area (University of Kentucky).

• Lawn or garden soil: white grubs, wireworms, rootworms.
• On leaves, in the open: leaf beetle larvae, or lady beetle larvae hunting aphids.
• Rotting log or stump: white grubs, wireworms and other wood-feeders.
• Inside living wood or firewood: flatheaded or roundheaded borers.
• Inside a nut, acorn or seed: weevil grubs.
• In flour, grain or cereal: pantry beetle larvae; the larvae key linked below lists them with sizes.
• On wool rugs, clothing or in closets: carpet beetle larvae.

For larvae found indoors, the larvae identification key lists the household ones room by room.

Shape is a good first clue. The long-legged, fast-moving, flat-headed larvae with forward jaws are predators, such as lady beetle and ground beetle larvae (University of Kentucky); ladybird larvae eat the same food as the adults (Wikipedia). Leave these alone on plants with aphids. The soft, slow, short-legged larvae in soil, wood or seeds are plant feeders or decomposers, and whether they are a problem depends on numbers and on what they are eating.

Usually to the type above, and for common pests often to the species. Beyond that it is harder: the University of Kentucky key itself stops at groups, and many larvae within a group look alike. For the best photo, shoot from the side so the legs (or lack of them) and the head show, then from above, with a ruler for scale, and include the soil, wood or food it was in. InsectLens names beetle larvae and the adults they become.

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.