The Twenty Most Toxic Caterpillars

Some caterpillars are poisonous to humans and to predators. These caterpillars get their toxicity from the plants

they eat. Generally, the brightly colored are poisonous; their color is a reminder to predators about their toxicity.

Wattle Cup Caterpillar (Calcarifera ordinata)

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It is certainly a beauty to admire but be careful because it does have a sting that is painful. This cute little fellow

likes roses, acacias and palms. As it turns to maturity it will transform into a brown/cream moth. The sting has

been described as “worse than 3 wasp stings”.

Spiny Oak-slug Caterpillar (Euclea delphinii)

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This caterpillar is colorful and cute but it stings. It is flattened and ovoid in outline, with spiny tubercules along

the back and sides. In the final instars it usually has two to four sets of black hairs at the tail end that can fall off,

called caltrop spines after the Roman defensive weapons. Its colors vary enormously. Favorite food plants include

oak, willow and other deciduous plants.

White Cedar Moth Caterpillar (Leptocneria reducta)

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These caterpillars grow to a length of about 4 cm. They have two small brown knobs on abdominal segments six

and seven, which are dorsal glands. They are covered in bristles, to which some people are allergic, giving them

urticaria. Not only do humans suffer from irritation from the hairs. The hairs have also been implicated in causing

abortions in horses.

Stinging Rose Caterpillar (Parasa indetermina)

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The Stinging Rose Caterpillar is one of the most brightly colored caterpillars. The body bears pairs of long,

horn-like, bristly spines and clumps of smaller spines which are characteristic of several of the slug caterpillars.

Hosts of the stinging rose caterpillar include apple, cottonwood, dogwood, hickory, oak, redbud, sycamore and

rose bushes.

Puss Caterpillar (Megalopyge opercularis)

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The Puss Caterpillar, or woolly slug, is the most poisonous caterpillar in the United States. It spits acid on

predators. The fur of the larva contains venomous spines that cause extremely painful reactions in human

skin upon contact. It has numerous common names, including Southern Flannel Moth, Pussy Moth, Puss

Caterpillar, Bolivia Bug, and Asp in Texas. It is visually striking in both larval and adult forms. The resemblance

of the larvae to soft, colorful cotton balls encourages people to pick them up and pet them. It can be found on

oaks, elms, citrus and other trees, and many garden plants such as roses and ivy.

Buck Moth Caterpillar (Hemileuca maia)

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This attractive and hairy caterpillar is the larva of the Buck Moth, a rare pine barren insect. It always has portion

of its population remaining underground in the pupal stage. If adults, caterpillars and eggs are destroyed by fire,

the Buck Moth population is re-established by the underground colony. It has a wider range, however, being quite

common in Louisiana. This larva bears large spines that can cause a painful irritation upon contact. This is a

large caterpillar, 1-3/4" to 2-1/4" long when mature.

Brown Tail Moth Caterpillar (Euproctis chrysorrhoea)

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This very hairy brown with red and white markings larva’s hairs break off very easily and are extremely irritating

to the skin. These hairs provide protection for this species throughout its life cycle: The brown and red grub is

covered in millions of tiny hairs that contain a toxin that can cause painful rashes, eye infections and, if inhaled,

serious breathing difficulties.

Saddleback Caterpillar (Acharia stimulea)

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This unique caterpillar that stings has stiff spines with potent poison glands. Stings can be very painful. They

can cause swelling, nausea, and leave a rash that can last for days. The Saddleback Caterpillar feeds on

many plants including hibiscus and palms.

Io Moth Caterpillar (Automeri io)

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The Io Moth, a very colorful North American moth, has a very beautiful larva also. The caterpillar is gregarious

in all its instars. As the larva develops, it will lose its orange color and will turn bright green and urticating, having

many spines that cause a lot of pain if touched. The spines have a poison that is released with the slightest

touch. It feeds on a wide range of plants, but ixora and rose are its favorite hosts.

Monkey Slug or Hag Caterpillar (Phobetron pithecium)

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This caterpillar is extremely bizarre in appearance. It has nine pairs of variable-length, lateral processes, which

bear the stinging hairs. These processes are curved and twisted and likened by some to the disheveled hair of

a hag, for which it is aptly named. It is found on various forest trees and ornamental shrubs, but is not as common

as the other stinging caterpillar species.

Hickory Tussock (Lophocampa caryae)

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This unique caterpillar is the larva of the Hickory Tussock Moth. It acquires chemical defenses from its host plants.

The hairs cause itchy rashes in some people. Symptoms are usually a skin rash (poison ivy-like) and sometimes

severe itching followed by a painful burning sensation.

Silverspotted Tiger (Halisidota argentata)

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Larvae are about 1 to 1-/2 inches long full-grown, densely covered with tufts of white, brown or black poisonous

hairs. Stings can be rather painful. Adults emerge in July and August and deposit eggs on needles or twigs of

coniferous trees. Larvae feed on Douglas fir, true fir, pine and other conifers.

Gypsy Moth Caterpillar (Lymantria dispar)

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The pretty colored with long hair caterpillar above is the larva of the Gypsy moth. Originally ranging from Europe

to Asia, it was introduced to North America in the late 1860s and has been expanding its range ever since. Larva

of the Gypsy Moth is not listed as “stinging hair caterpillars,” but their hairs can cause dermatitis, especially in

sensitive persons.

Monarch Caterpillar (Danaus plexippus)

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This gorgeous caterpillar is the larva of one of the best known butterflies in the world – the Monarch Butterfly.

Monarch caterpillars usually advertise themselves with brightly striped or colored in black, red and yellow—the

danger colors. Any predator that attempts to eat a caterpillar with an aggressive defense mechanism will learn

and avoid future attempts. Monarchs are foul-tasting and poisonous due to the presence of cardenolide

aglycones in their bodies, which the caterpillars ingest as they feed on milkweed. Both forms advertise their

unpalatability with bright colors and areas of high contrast on the skin or wings. This phenomenon is known

as aposematism.

Pipevine Swallowtail Caterpillar (Battus philenor)

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The reddish-brown caterpillar of the Pipevine Swallowtail has rows of fleshy, red or black colored tubercles on

its back. These caterpillars are not only toxic, they are also foul-tasting and their scarlet coloration is a warning

to hungry birds to stay away. Host plants for the caterpillars include the Pipevine and other species. Pipevines

confer a poisonous quality to the larvae and resulting adults, much as the monarch butterfly obtains protection

by feeding on milkweed or heliconiines by feeding on passion flowers. Caterpillars accumulate the powerful toxins

found in these plants.

White Stemmed Gum Moth (Chelepteryx collesi)

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The White-stemmed Gum Moth can be found in eucalypt forests and woodlands of south-eastern mainland

Australia. Caterpillars of White-stemmed Gum Moths grow to approximately 10cm long. This very scary looking

caterpillar can be quite dangerous to touch due to toxins in the bristles. They are grey and black in color with

tufts of reddish bristles. The bristles of this caterpillar and those of the cocoon break off when touched. The

bristles easily penetrate skin, causing irritation and occasionally an allergic reaction.

Bag Shelter Moth Caterpillar (Ochrogaster lunifer)

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These caterpillars are also known as Processionary Caterpillars. Do no touch these caterpillars. The larva have

a brown head, the body is grey with dark bands and numerous long, white irritant hairs. They live inside a brown

silken bag and come out at night to feed on host plants chiefly wattles and Grevillea striata commonly known as

Beefwood. When traveling from tree to tree they form a procession, hence the common name.

Lonomia obliqua Caterpillar

Contact with the Lonomia caterpillar causes numerous accidents, especially in Venezuela and the southern region

of Brazil. It is considered a public health problem. The Lonomia obliqua venom causes disseminated intravascular

coagulation and a consumptive coagulopathy, which can lead to a hemorrhagic syndrome. In vivo and in vitro

studies have shown that the venom of the Lonomia caterpillar contains several toxins with procoagulant,

anticoagulant and antithrombotic activities. Persons who have been in contact with Lonomia obliqua caterpillars

present external and internal bleeding and opening of recently healed wounds.

Lonomia achelous Caterpillar

The most aggressive defenses are bristles associated with venom glands, called urticating hairs; venom among

the most potent defensive chemicals in any animals is produced by the South American silk moth genus Lonomia.

It is an anticoagulant powerful enough to cause a human to hemorrhage to death. The bodily secretions of the

Lonomia achelous caterpillar cause a severe and often fatal acquired bleeding diathesis in humans.

Cinnabar Moth Caterpillar (Tyria jacobaeae)

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The larvae absorb bitter tasting alkaloid substances from the food plants, and assimilate them, becoming

unpalatable themselves. The bright colors of both the larvae and the moths act as a warning sign so that

they are seldom eaten by predators.

All species have small hairs that can irritate the skin, both through direct contact and from airborne hairs.

Caterpillars produce venoms that are stored in these hairs as a defense against predators. Caterpillar

species from approximately 12 families of moths or butterflies worldwide can inflict serious human injuries

ranging from urticarial dermatitis and atopic asthma to osteochondritis, consumption coagulopathy, renal

failure, and intracebral hemorrhage. Skin rashes are the most common, but there have been fatalities.

Beware and watch out for the kids always.