Types of Venomous Caterpillars (With Pictures) – Identification Guide
Venomous caterpillars have poisonous bristles, spines, and barbs on their body that can cause a nasty sting. Some types of venomous caterpillars look soft and cute, but their hairy bodies hide toxin-filled spines that can lodge into the skin. Other caterpillars with poisonous spines look dangerous because they have bright coloring, sharp-looking spines, and a menacing appearance.
A sting from a venomous caterpillar can result in skin swelling, redness, itchiness, or a burning sensation. However, it’s good to remember that “toxic” caterpillars don’t attack humans or bite. Adverse skin reactions from a venomous caterpillar’s sting only happen when you handle them.
Identifying species of venomous caterpillars is vital to knowing which ones to avoid. However, many species of hairy caterpillars don’t contain poison-filled sacs and spines and are entirely harmless. Of course, if you’re unsure about the identity of a spiky caterpillar, it’s best to avoid handling it.
This article is an identification guide on how to recognize species of venomous caterpillars. You will learn about the features and characteristics of 14 caterpillar species that have poisonous spines and toxic barbs.
What Makes a Caterpillar Venomous?
Stinging, venomous caterpillars have hollow spiny barbs called urticating setae connected to poisonous glands. Hairy and spiky caterpillars use these as a defensive mechanism to deter predators. However, touching the quill-like hairs on the caterpillars releases poison resulting in mild to adverse skin reactions.
According to scientists, symptoms of touching a venomous caterpillar are wide and varied. However, the most common skin reactions include blistering, mild to severe burning pain, swelling, hives, dermatitis, and tissue damage. In addition, some caterpillar species have toxins that can cause symptoms like rheumatoid arthritis.
The toxic chemicals in some caterpillars make them poisonous to birds and small animals. Typically, poisonous caterpillars have bright markings to warm predators. However, the stinging caterpillars will taste foul to birds, and they will quickly learn to avoid them.
Types of Venomous Caterpillars (With Pictures) – Identification Guide
Venomous caterpillars come in all shapes and sizes, and some look like harmless butterfly or moth larvae. Therefore being able to identify dangerous caterpillars can help you avoid getting stung. Please read on to learn about identifying features of the most common caterpillars with venomous setae.
Southern Flannel Moth Caterpillar (Megalopyge opercularis)
The hairs of the Southern flannel moth caterpillar conceal sharp venomous spines
The southern flannel moth caterpillar is a venomous caterpillar that can be recognized by its covering of long, wavy brown hairs. The furry caterpillar is usually golden brown or dark gray but can sometimes be grayish white. The soft-looking hairs are deceiving because they hide venomous spines that can cause a nasty sting.
The venomous hairy brown southern flannel caterpillar measures 1” (25 mm) long, and its oval body tapers at the tail. It emerges bright yellow with long, fine setae on its body. Through its several instars (growth stages), it becomes a mass of hair—some describe it as having a bad hair day.
Also called the puss caterpillar, Italian asp, fire caterpillar, woolly slug, or Texas asp, the southern flannel caterpillar is considered a dangerous caterpillar.
The southern flannel caterpillar stings result in severe “white hot” pain that can feel like being hit by a blunt force. Symptoms of the caterpillar sting include burning, blisters, nausea, headaches, or breathing difficulties.
Venomous Caterpillar Identification
The southern flannel caterpillar is identified by its luxuriant hairy coat that is golden brown or gray.
Black-Wave Flannel Moth Caterpillar (Megalopyge crispata)
The sharp venomous spines of the black-wave flannel moth caterpillar are hidden underneath its white hairs
The black-wave flannel moth is a venomous, stinging caterpillar covered in long, spindly creamy-white hairs. The non-stinging hairs hide sharp spines attached to poisonous glands. Even lightly brushing against the caterpillar’s wispy hairs can cause a painful sting. If you see a bushy-looking white caterpillar, then it’s best to leave it alone.
The black-wave flannel moth caterpillar measures 0.7” to 1.5” (20 – 40 mm) long. The early growth stages of the moth caterpillar differ from the later stages. The long wispy white setae look like a frilly mess of hair. But as the caterpillar matures, it develops a velvety appearance.
Also called the white flannel moth or crinkled flannel moth, the hairy larva is common on the southeastern coast of North America. This bug is on the list of Florida’s venomous caterpillars.
Venomous Caterpillar Identification
The black-waved flannel moth caterpillar is recognized by its mass of frilly, creamy-white hairs that become soft and furry as the larva matures.
Saddleback Caterpillar (Acharia stimulea)
The saddleback caterpillar has spiny venomous horns that cause painful sting
The saddleback caterpillar is an easily recognizable venomous caterpillar due to its large spike-covered fleshy horns at both ends. The identifying features of this fearsome caterpillar are tufts of urticating hairs, a bright lime-green abdomen with a saddle marking, and eye-like creamy-yellow dots at its head.
The relatively small green and brown saddleback caterpillar grows up to 0.78” (20 mm) long and 0.27” (7 mm) wide. You can find this striking caterpillar in warmer states in North America, feeding on oak, maple, holly, elm, and dogwood trees.
The saddleback caterpillar’s tubercles and spines release toxins when broken. A saddleback caterpillar venomous sting results in burning sensations, redness, blistering, migraines, and gastrointestinal symptoms.
Venomous Caterpillar Identification
The saddleback caterpillar is identified by its lime-green blanket-like marking with an oval brown patch in the center. Additionally, fleshy spines poking out from the venomous caterpillar giving it a menacing appearance.
Io Moth Caterpillar (Automeris io)
The io moth caterpillar has green spikes that feel very unpleasant if their venom penetrates your skin
The larval stage of the io moth is a large, brightly colored venomous green caterpillar covered in tufts of urticating spines. Its large size, green color, and red and creamy-white stripes along its abdomen make the io moth caterpillar easily recognizable. The io moth caterpillar grows up to 2.7” (70 mm) long.
The io moth starts life as an orange or reddish-brown caterpillar before turning into a large green one. Its green body is covered in bands of spiny tufts containing toxins. In their final instar, a prominent dark red and white band is visible along its sides.
Venomous Caterpillar Identification
The identifying features of the io moth caterpillar are its green body with a lateral abdominal red and white stripe, reddish prolegs, and spiky tufts of venomous spines.
Hag Moth Caterpillar (Phobetron pithecium)
The venomous hairs on the hag moth caterpillar can cause skin irritation
The hag moth larva is one of the strangest venomous caterpillars you’ll come across. The unusual furry brown caterpillar has 18 spine-covered projections on its flattened, hair-covered body. The hag moth looks more like the skin of a brown spider than a moth caterpillar.
Also called the monkey slug, hag moth caterpillars measure 0.6” to 1” (15 – 25 mm) long. You’ll find the bizarre-looking larvae on apple, birch, oak, chestnut, willow, and hickory trees. The brown bug is common throughout the eastern United States.
Venomous Caterpillar Identification
The hag moth is an easily recognizable brown caterpillar due to its characteristic curly projections covered in urticating hairs.
White Cedar Moth Caterpillar (Leptocneria reducta)
The white cedar moth caterpillar is covered in venomous urticating hairs all over its body
The white cedar moth larva is a cylindrical dark brown caterpillar covered in irritating bristles. The dark caterpillars have a distinct spiny appearance due to the long pencil setae covering its body. Other features to identify it are its orange feet and faint yellow line along its back.
White cedar moth caterpillars measure around 1.57” (40 mm) long. A characteristic habit of these stinging caterpillars is that they move in groups to defoliate chinaberry or white cedar trees.
These urticating hairs can sting, causing allergic skin reactions like dermatitis, redness, and itching in some people.
Venomous Caterpillar Identification
The venomous white cedar moth caterpillar is identified by its dark brown cigar-shaped body, orange prolegs, and sometimes a dim yellow line along its back.
Spiny Oak Slug (Euclea delphinii)
The green and orange spiny oak slug caterpillar has venomous spines that can cause adverse reaction
The venomous spiny oak slug is an unusual caterpillar with fleshy, spine-covered protections along its back and sides. The eye-catching larva is typically green with two orange stripes on its back. Additionally, greenish ringed patterns give the caterpillar a distinct pattern. The spiny oak slug measures up to 0.78” (20 mm).
The hollow spines on the spiny oak caterpillar attach to toxin glands. These can easily puncture the skin, releasing the poison that results in an adverse dermatological reaction. Symptoms of a spiny oak slug sting include localized redness, stinging sensation, and skin inflammation.
Venomous Caterpillar Identification
The spiny oak caterpillar is a bizarre green caterpillar with large fleshy orange projections on its back, two orange bands, and tufts of toxin-filled spines around its sides.
Buck Moth Caterpillar (Hemileuca maia)
The buck moth caterpillar is a large stinging caterpillar and one of the most venomous ones
The larva of the buck moth is a large, dark brown spiky caterpillar covered in tiny white dots. The spine-covered, brownish multi-branched projections on the dark caterpillar are attached to venomous glands in its body. The black or dark brown larva also has reddish-brown feet. Some Hemileuca maia species appear as brown striped caterpillars.
The buck moth caterpillar grows up to 2.5” (65 mm) before its pupal stage. You will often find the spiny black caterpillar feeding on various species of oak trees.
This venomous caterpillar has hollow quill-like hairs attached to poison sacs. A sting from the caterpillar can cause skin itching, burning, and severe irritation. In some cases, the caterpillar’s sting can cause nausea.
Venomous Caterpillar Identification
The buck moth caterpillar is a venom-carrying larva, identified by its black body covered in rows of multi-branched spines and white spots.
White Flannel Moth Caterpillar (Norape ovina)
The venomous spines on the white flannel moth caterpillar can cause a painful sting
The larva of the white flannel moth is an eye-catching yellow caterpillar with a large black band on its back and rusty-red ends. Other identifying features of the venomous caterpillar are its tufts of yellow hairs, wispy black setae, short stinging needle-like hairs, and whitish spots on its back.
The white flannel moth caterpillar grows 1” to 1.25” (25 mm to 31 mm) long. The yellow and black caterpillar is common in Florida, Texas, Washington, D.C., and south toward Mexico.
Doctors say that symptoms of a white flannel moth caterpillar sting are urticarial dermatitis caused by venom-filled hairs puncturing the skin.
Venomous Caterpillar Identification
The white flannel moth caterpillar is easily recognized by its dark brown or black band on its abdomen and contrasting bright yellow tufts of stinging hairs. Also, its tail and head ends are orangey-red, with black silky hairs covering its body.
Stinging Rose Caterpillar (Parasa indetermina)
The stinging rose caterpillar has clusters of toxic spikes along its body
The stinging rose caterpillar is a brightly colored caterpillar with yellow or orange spine-covered spikey toxin-filled projections. The venomous stinging caterpillar is easily recognizable by its black, white, orange, and red line running along its back. The colorful but dangerous caterpillar measures 1” (25 mm) long.
Each of the seven pairs of spiny horns is filled with toxins that cause severe irritation. Brushing against the caterpillar results in a nasty sting, with skin swelling and rashes that can last for days.
Venomous Caterpillar Identification
The stinging rose caterpillar is a colorful venomous caterpillar, easy to recognize by its flattened, oval shape, seven pairs of fleshy conical projections, and yellow, red, orange, and black colors.
Pine Processionary Moth Caterpillar (Thaumetopoea pityocampa)
The venomous pine processionary moth caterpillar can be found in coniferous forests
The larva of the pine processionary moth is a black caterpillar with bands of yellowish-white toxin-filled hairs, amber spots, and a rounded head. The distinctive habit of this stinging caterpillar is its processionary behavior as hundreds of hairy caterpillars move in a line to find new pine trees to defoliate.
A line of pine processionary moth caterpillars
Mature pine processionary caterpillars grow up to 1.57” (40 mm) long. The irritating hairs covering the black worm-like creature contain urticating chemicals that cause intense and continuous itching. The caterpillar’s sting may result in hives, contact dermatitis, pain, and small red bumps.
The most significant damage pine processionary caterpillars cause is in coniferous forests. According to some sources, this destructive caterpillar causes economic damage to forests in southern Europe, Asia, and North Africa.
Venomous Caterpillar Identification
The venomous stinging pine processionary moth caterpillar is primarily recognized by its habit of caterpillars moving in a line. In addition, the dark gray to black caterpillars have white urticating hairs.
Giant Silkworm Moth Caterpillar (Lonomia obliqua)
The giant venomous silkworm moth caterpillar can be dangerous
The larva of the giant silkworm moth is a dangerous hairy brown caterpillar with venomous bristles. The cylindrical worm-like brown caterpillar has white and tan markings on its back. The caterpillar is covered in multi-branched greenish spines containing a potentially deadly venom.
Giant silkworm moth caterpillars measure 1.77” to 2.1” (45 to 55 mm) long. Although they are typically brown, the caterpillars can also be a green color.
The venomous spines of Lonomia obliqua contain a poison that has anticoagulant properties. This can cause swelling, redness, pain, and internal bleeding.
Venomous Caterpillar Identification
The giant silkworm moth caterpillar’s identifying features are its soft, pale green venomous spines surrounding its brown body. In addition, these caterpillars often have white, black, or rusty-brown bands on their back.
American Dagger Moth Caterpillar (Acronicta americana)
The venomous American dagger moth caterpillar can be identified by its distinct yellow-whitish hairy look
The larva of the American dagger moth is a venomous hairy yellow-whitish caterpillar with several pairs of long black pencil bristle hairs. The slender caterpillars have stinging hairs containing toxic venom that can cause severe skin irritation. The furry pale yellow caterpillar grows to 2” (50 mm) long.
The American dagger moth caterpillar feeds on the foliage of oak, maple, elm, ash, and other hardwood trees. The caterpillars are most active from July through October. The venomous yellowish caterpillar does harm when its toxic bristles break off and get embedded in the skin.
Venomous Caterpillar Identification
The American dagger moth caterpillar is easy to identify due to its furry white-yellowish hairs with several long black pencil hairs protruding from its body.
Hickory Tussock Caterpillar (Lophocampa caryae)
The hairy hickory tussock caterpillar has black patterns along its white back
The larva of the hickory tussock moth is a black and white caterpillar covered in rash-causing tuffs of irritating hairs. Identifying features of the worm-like caterpillar are long white pencil hairs at either end, bands of black dots traversing a white body, and irritating black tufts on its back.
Hickory tussock caterpillars grow up to 1.77” (45 mm). The caterpillars tend to feed in large groups and can completely defoliate willow, pecan, hickory, and walnut trees. However, the gorging white and black caterpillars rarely damage trees entirely.
The urticating tufts can cause skin irritation because the microscopic, barbed spines can lodge in the skin. According to some reports, the caterpillar isn’t venomous, but its stinging spines cause skin reactions like venomous barbs would.
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