North American caterpillars

2057 Garden Tiger (Arctia caja) caterpillar - fully grown © Steve OgdenThis North American caterpillar gallery has been added in response to the increasing number of caterpillar identification enquiries being received from US states and Canada.

Your photos of some of the most commonly sighted caterpillars are greatly appreciated and once added to the site will hopefully help others with caterpillar identification.

Caterpillars and larvae are terms used for the larval stage of an insect. In many states some species of caterpillar are referred to as worms, cutworms or bollworms; many of which, such as the Cotton Bollworm, are pests of crops.

Please note that there are some hairy caterpillars found in many American states with hairs that can cause allergic skin reactions.

2026 The Vapourer Moth (Orgyia antiqua) caterpillar - brown tufted form © Steve Ogden

Identification of American caterpillars

When identifying caterpillars the following pointers may be helpful.

Many caterpillars radically change appearance as they grow and moult (change skins).

Counting the legs may help by placing the caterpillar in a certain genus or sub family of insects.

Some caterpillars found in the United States may also occur in other parts of the world and although the English species name may differ the scientific latin name will be the same. An example being Orgyia antigua which is better known as the Rusty Tussock Moth in the US but called The Vapourer moth in the UK.

So when identifying a caterpillar it may also help to look at the British caterpillar gallery which also includes some species occurring in other countries and continents of the world.

Please note

There is still much to learn about the early stages of many moths and butterflies. Whilst every effort is made to provide accurate identifications and information errors could occur. Should an error be spotted please let us know.

American caterpillar pests

Eastern Tent caterpillars in Idaho, USA on silk web photo © Amanda FingersonSeveral species of caterpillars found in the United States are considered pests of trees and crops.

These include the Tent caterpillars of which there are several different species in North America. The Eastern Tent caterpillar, Western Tent caterpillar and Forest Tent caterpillar are three of the most commonly enquired about caterpillars in this family. The ‘Tent’ referring to the protective silk web in which the caterpillars gregariously live when not feeding.

This photo of Eastern Tent caterpillars was taken by Amanda Fingerson in the state of Idaho.

To help others identify hairy Tent caterpillars please continue to send in caterpillar images which can be added to the site with accreditation.

American hairy caterpillars

White Marked Tussock moth caterpillar in LA, USA photo © Lynn NorwoodThere are some hairy caterpillars in the United States that have irritating (urticating) hairs which may cause skin reactions and should be treated with caution.

Many of the caterpillars of the Lymantriidae moth family, which includes the Tussock moth caterpillars, are known throughout the world for having hairs that can cause health problems.

The White Marked Tussock moth is a member of the Tussock family and the photo of the one shown was taken by Lynn Norwood in Los Angeles, California, USA.

American stinging caterpillars

Stinging Saddleback caterpillar Acharia stimulea,North Carolina, USA © 2015 Shawn WilliamsThe extraordinary looking Saddleback caterpillar, Archaria stimulea, is a common species in much of North America.

It’s a member of the Limacodidae family of moths which are best known for the stinging hairs of their caterpillars.

Every year there are many reports of Saddleback caterpillars, also referred to as slug caterpillars, stinging people in many states.

It is one of the most frequently enquired about caterpillars and the one shown left was recorded by Shawn Williams in North Carolina.

Skin contact with these caterpillars should definitely be avoided.

Large American butterfly caterpillar

Giant Swallowtail butterfly caterpillar, Texas, USA © L.WilderFortunately most caterpillars are harmless and play a vitally important part in our ecosystem.

Many pupate and emerge as beautiful butterflies and moths to be enjoyed and appreciated by all.

This photo of the caterpillar of the beautiful Giant Swallowtail butterfly was sent in by Laura Wilder taken on a Citrus Tree in her garden on the Gulf Coast of Texas, USA.

These beautiful butterflies have caterpillars that resemble bird droppings to help avoid detection by predators.

Indeed, caterpillars come in a huge variety of different shapes, sizes and colour designed to camouflage and protect themselves from predators.

Largest caterpillar in the United States

Regal Moth caterpillar (Citheronia regalis) searching for place to pupate in the soil, New Jersey, USA © J.PaceMany caterpillars are less than 2 inches long but some are much longer.

This Regal Moth caterpillar is one of the largest caterpillars found in North America reaching almost 6 inches in length and was recorded by Johnathan Pace in the state of New Jersey.

Many of the other large caterpillars found in the US are members of the Hawk-moth family Sphingidae.

Caterpillars in this family are found all over the world and easily identified by their tail spikes.

These large caterpillars are frequently observed when they leave the food plant to wander over the ground in search of somewhere to pupate in the soil.

White fluffy caterpillars

Butternut Woollyworm found feeding on Hickory in Idaho, USA - photo © Jill GambonSome caterpillars in the United States look so extraordinary that it’s not always immediately obvious they are actually caterpillars.

Often the first task is deciding which order of insects such as butterfly or moth (Lepidoptera), fly (Diptera) or beetle
(Coleoptera) a caterpillar belongs to.

This photo of the extraordinary Butternut Woolly Worm, the caterpillar of the sawfly Eriocampa juglandis, was received from Gill Gambon, taken in her garden in Rockland, in the state of Massachusetts.

These are just a sample of your enquiries. Many more of your images will be added to the gallery with accreditation and those of particular interest included in a ‘latest sightings’ news item – so please keep sending them in to Steve Ogden – email address –

Many thanks.

Please note: even if the caterpillar is not immediately identified the photo can still be added to the gallery for others to identify.

It should be noted that while great effort is put into providing correct information and identifications errors could occur. Should you be aware of incorrect information please don’t hesitate to contact us.

The US caterpillar gallery is presently being updated to accommodate many new photos

Physicodes-case bearing moth caterpillars
Limacodidae-Slug caterpillars
Megalopygidae-Flannel moth caterpillars
Butterfly caterpillars
Geometridae-Loopers, Inchworms and Spanworm moth caterpillars
Bombycidae-true Silkworms and Apatelodine Moths
Lasiocampidae- Tent moth and Lappet moth caterpillars
Saturniidae-Giant Silkworms and subfamilies Ceratocampinae and Hemileucine.
Imperial Moths, Royal moths, Oakworms, Buck Moths
Notodontidae-Prominent moth caterpillars
Noctuidae-Owlet, Cutworm and Underwing moth caterpillars
Pantheidae- Pantheas and Yellowhorn moth caterpillars
Lymantriidae- Tussock moth caterpillars
Sphingidae-Hawkmoth, Sphinx and Hornworm moth caterpillars
Arctiidae-Tiger moth and Wasp moth caterpillars