Caterpillar identification with a hazard check
Caterpillar identifier: what is this caterpillar, and can it sting?
The caterpillar identifier names the caterpillar from one photo, says whether its hairs or spines can sting or irritate skin, and whether it is a garden pest to remove or a butterfly to leave be.
The result
What the caterpillar identification tells you
One photo, one report: the name first, then what it means for your hands, your kids, your pets and your plants.
The caterpillar and the butterfly or moth it turns into, with how sure the match is and the features that point to it.
Caterpillars and sawfly larvae it is often confused with, and the detail that tells them apart.
One plain call, with the reason. Never a promise that a caterpillar is safe to touch.
- Low concern
- Irritating hairs
- Stings: do not touch
Whether it has irritating hairs, stinging hairs or spines, and where on the body they are.
Whether it eats your plants and which ones, or is a butterfly or moth worth leaving on its host plant.
Leave a stinging one alone and keep people away, protect the plant, pick off a pest that does not sting, or ask your local extension office.
Method
How the caterpillar identifier works
- 01
Photograph it where it sits
Side view, the whole caterpillar in focus, with the leaf or plant it is on. Do not pick it up: some hairs sting through a light touch.
- 02
Add the plant and the place
The plant it was on and your town or state. Host plant and region narrow the species, since colour alone can change as a caterpillar grows.
- 03
Get the name and the look-alikes
The caterpillar identifier names the species, the butterfly or moth it becomes, and the look-alikes to rule out, with how sure the match is.
- 04
Read the hazard check and garden plan
Whether its hairs or spines can sting or irritate, whether it eats your plants, and what to do: leave it and keep people away, protect the plant, or pick off a garden pest that does not sting.
Photos
How to photograph a caterpillar for identification
Colour can change from one stage to the next, so show the shape, the legs, the hairs and the plant.
Do
Side view, whole body
From the head to the tail, so the legs, the prolegs and any horn or tail show.
Include the plant
Keep the leaf or stem it is on in the frame: the host plant is one of the best clues.
Hairs in focus
Make sure the hairs, spines or tufts are sharp. If they are blurred, retake the photo from the same distance and run it again.
Daylight
Shade or overcast light shows true colours. Flash can wash out stripes and spots.
Don't
Do not touch it
Never pick up a fuzzy or spiny caterpillar for a photo, and keep children's hands away. Move the leaf, not the caterpillar.
No blurry close-ups
If the camera will not focus, step back a little and crop later.
Not from straight above only
From above, the legs and the underside are hidden; add a side view.
Touched a caterpillar and it burns?
Do not wait for the caterpillar identification. Tape can lift broken spines out of the skin; then wash with soap and warm water and use an ice pack. For a severe reaction, such as trouble breathing, call 911 or your local emergency number. In the US, the Poison Help line, 1-800-222-1222, is free, day and night.
Reference
Is this caterpillar poisonous? How stinging caterpillars work
Fuzzy, bright or cute is no guide. Look for hairs and spines, and keep your hands off until you know.
Many caterpillars are covered in pointed or barbed hairs against predators. On human skin these hairs can cause irritation and rashes.
Some species have hollow hairs with a poison gland at the base, called urticating setae. They pierce the skin and release venom, which can cause a painful burning feeling and inflammation.
Most stinging caterpillars belong to the puss caterpillars, the slug caterpillars and the giant silkworm moths.
Most come from careless handling or brushing against trees and shrubs while mowing or doing yard work.
Doctors call the rash from caterpillar or moth hairs lepidopterism, a contact dermatitis.
Source: Clemson HGIC (Stinging Caterpillars); Wikipedia (Lepidopterism), as of
Reference
Stinging caterpillar identification: species not to touch
These are the stinging caterpillars a South Carolina extension guide names. Where you live, others may be common.
- Puss caterpillar
Covered in long, soft-looking hair, from greyish white to golden brown, often with an orange streak. The fur hides venomous spines that cause extremely painful reactions. Also called asp or southern flannel moth caterpillar.
- Saddleback caterpillar
The most common slug caterpillar: a charcoal grey body with a lime green saddle across the middle. It is also found on garden crops, corn among them.
- Io moth caterpillar
Lime green, with bright horn-like spines and four rows of stinging hairs; it can reach about 2.5 inches, the largest stinging caterpillar commonly met in South Carolina.
- Slug caterpillars
Varied in look: long fleshy lobes covered with brown hairs, or colourful triangular projections.
Source: Clemson HGIC (Stinging Caterpillars); Wikipedia (Megalopyge opercularis), as of
Reference
Hawk moth caterpillar identification: hornworms on tomato plants
A big green caterpillar on a tomato plant is often a hornworm, the caterpillar of a hawk moth.
- The horn
- Most hawk moth caterpillars have a horn at the rear end, which may shrink to a button or vanish in the last stage. They have five pairs of prolegs and usually no hairs.
- Colour and stripes
- Many are cryptic greens and browns; diagonal slashes along the side are common.
- The sphinx pose
- At rest, the caterpillar often holds its legs off the leaf and tucks its head under, which gives the sphinx moth its name.
- Tomato or tobacco hornworm
- The two are closely related and sometimes confused, and both feed on tomato, pepper, eggplant and potato, so the plant does not tell you which it is.
- In the garden
- The tomato hornworm can be a major garden pest. Gardeners pick them off by hand; under a UV blacklight at night they glow bright green.
Source: Wikipedia (Sphingidae; Manduca quinquemaculata), as of
Reference
Caterpillar or not? Look-alikes and common finds in North America
Caterpillars are the young of butterflies and moths, insects of the order Lepidoptera. A few other insects' larvae look the same at first sight.
- Sawfly larva
Looks like a caterpillar but is related to bees and wasps. It has six or more pairs of prolegs; a true caterpillar has at most five, with tiny hooks on them.
- Inchworm
A looper caterpillar of the moth family Geometridae that has lost nearly all its prolegs, so it moves in loops, as if measuring the ground.
- Woolly bear
The banded caterpillar of the Isabella tiger moth: brown hair in the middle, black at both ends. It overwinters as a caterpillar.
- Fall webworm
Builds webbed nests on the branches of hardwood trees in late summer and fall; a pest, but it does not harm otherwise healthy trees.
- Monarch caterpillar
Feeds on milkweed. From its second stage it has white, yellow and black bands across the body and pairs of black tentacles.
Source: Wikipedia (Caterpillar; Pyrrharctia isabella; Hyphantria cunea; Monarch butterfly), as of
Scope
What a caterpillar identifier can and cannot tell from a photo
A photo can show
- The species, or the group, of a caterpillar from North America and beyond
- Look-alikes such as sawfly larvae, and how to tell them apart
- Whether that kind of caterpillar has stinging or irritating hairs or spines
- Whether it eats garden plants, and what to do about it
Only an expert with it in hand can tell
- Any promise that a caterpillar is safe to touch or to let a child hold
- How your skin, or your pet, will react: ask a doctor or a vet
- Treatment for a sting or a rash: that is for a doctor or poison control
- The species for certain when only part of the caterpillar shows
A name is the start. The caterpillar identifier also says whether its hairs sting or irritate, whether it eats your plants, and what to do with it.
Next
After the caterpillar identification
- 01
Admire it from afar
The extension advice on stinging caterpillars is short: learn them and avoid them. Watch, photograph and walk away.
- 02
Keep people away from stinging ones
Do not try to move a fuzzy or spiny caterpillar. Keep children and pets away from it, and wear long sleeves for yard work near shrubs and trees.
- 03
Hornworms on tomatoes
Check the leaves near the stem by day and the outer leaves in the evening, and pick hornworms off by hand. A UV light at night makes them glow.
- 04
Stung or a rash?
Lift broken spines with tape, wash with soap and warm water, and use an ice pack. Call your doctor, or in the US the Poison Help line, 1-800-222-1222.
America's Poison Centers
Free caterpillar identifier: no card, no trial
Trying the caterpillar identifier here is free. The form asks for no card, no account and no trial, so there is nothing to cancel.
Limits
What a caterpillar identifier cannot promise
A photo cannot decide that a caterpillar is safe to touch, and the report is not medical advice. For a sting, a rash or a reaction in a child or a pet, call a doctor, a vet or poison control. For a heavy infestation on trees, ask your local extension office or an arborist.
FAQ
Caterpillar identifier questions
Can I take a picture of a caterpillar to identify it?
Yes. Photograph it from the side with the plant it sits on, and add where you found it. The caterpillar identifier names it and says whether its hairs or spines sting.
What is this caterpillar?
Upload a clear side view. The caterpillar identification names the species, the butterfly or moth it becomes, and the look-alikes, with how sure the match is.
How do I tell what caterpillar I have from a photo?
Look past the colour, which can change as a caterpillar grows. The shape, the hairs or spines, a horn at the rear, the stripes and the host plant tell more. The caterpillar identifier reads them all from one photo plus the place you add.
How to tell if a caterpillar is poisonous or can sting you?
You cannot tell safely by touch. Stinging caterpillars carry hollow hairs or spines with venom, and soft-looking fur can hide spines. Treat any fuzzy or spiny caterpillar as one that stings until you know.
Are fuzzy caterpillars poisonous, and which ones should I avoid touching?
Many fuzzy caterpillars have hairs that irritate skin, and some sting. In the US South the puss caterpillar, which looks soft and furry, causes most stings. The saddleback and the Io moth caterpillar sting too.
Is a caterpillar identifier safe for poisonous or stinging caterpillars?
Yes, that is why it works from a photo: you never need to touch the caterpillar. Keep your distance, and the report says whether it is one to avoid.
What should I do if I get stung by a caterpillar that the app flags as hazardous?
Lift any broken spines with tape, wash the skin with soap and warm water, and put on an ice pack. Call a doctor or poison control; for a severe reaction, such as trouble breathing, call 911 or your local emergency number.
Is there a free app that can identify caterpillars?
This caterpillar identifier works as an app in your browser, with nothing to install. Trying the form here is free and needs no card, no account and no trial.
Is this a caterpillar identifier app?
It is a caterpillar identifier app that runs online, on a phone or a computer. Take the photo with your phone camera and upload it in the browser.
Can I identify a caterpillar from a photo online for free?
Yes, trying the form is free. The report names the caterpillar and adds the hazard check and what to do in your garden.
How can I tell if a caterpillar is damaging my plants or helping them?
Caterpillars eat leaves, but not all are pests worth removing. The report says whether it is a known garden pest, such as a tomato hornworm, or a butterfly such as the monarch, whose caterpillar feeds on milkweed.
Found this little guy in my garden: is it a friend or foe for my plants?
Upload a photo with the plant it sits on. The report gives a friend or foe call with the reason, and what to do: leave it, protect the plant, or pick off a pest that does not sting.
What will get rid of caterpillars on my plants without harming butterflies?
Start with the name. A hornworm on a tomato can be picked off by hand; a monarch on milkweed is best left alone. For stinging caterpillars, an extension guide says they are rarely met in large numbers and need no chemical control.
What looks like a caterpillar but is not a caterpillar?
Sawfly larvae, related to bees and wasps, look like caterpillars. Count the prolegs on the belly: a sawfly larva has six or more pairs, a caterpillar at most five.
Do caterpillars turn into moths?
Caterpillars are the larvae of butterflies and moths, and many become moths: the hornworms, the woolly bear and the stinging ones all turn into moths. The report names what yours turns into.
Can the caterpillar identifier tell a tomato hornworm from a tobacco hornworm?
From a clear side photo it names the likely one and says if it cannot tell. The two are close relatives and feed on the same plants, so the plant does not settle it.
Can it identify a caterpillar rash?
No. A rash does not show which caterpillar caused it, and it needs a doctor. The caterpillar identifier works from a photo of the caterpillar itself.
Found a caterpillar on the plants or the patio?
Take one clear side photo from a safe distance and see what it is, whether it stings, and what to do next.