20 Types of Caterpillars in Louisiana: From Monarchs to Stinging Asps
October 21, 2026
Walk under a live oak in Baton Rouge during April and you might get an unpleasant surprise falling onto your shoulder. Louisiana’s warm, humid climate and mix of oak forests, wetlands, and backyard gardens support an unusually wide range of caterpillar species, and not all of them are the harmless, fuzzy kind kids like to pick up. Some of the types of caterpillars in Louisiana are future monarchs and swallowtails; others carry venomous spines that can send a person to urgent care.
This guide walks through 20 caterpillars you are likely to encounter across the state, from backyard milkweed patches to oak-lined city streets. Each one gets a plain-language look at what it looks like, what it eats, and whether it’s safe to touch. For a broader sense of just how many caterpillar species exist in North America, Louisiana’s count is only a slice of a much bigger picture covered in our guide to how many types of caterpillars exist.
Pro Tip: If you can’t positively identify a caterpillar, treat it like a stranger’s dog — admire from a distance rather than picking it up. Several of Louisiana’s most common species carry venomous spines that activate on contact.
1. Monarch Caterpillar
The monarch caterpillar (Danaus plexippus) is probably the most recognizable larva in the state, with bold yellow, black, and white stripes running the length of its body. It feeds exclusively on milkweed, pulling in toxic compounds from the plant that make both the caterpillar and the adult butterfly unpalatable to most predators. Louisiana sits along a major monarch migration corridor, so gardeners who plant native milkweed often see several generations move through a single backyard patch between spring and fall.
Families across the Gulf Coast raise monarchs indoors to watch the full transformation from egg to chrysalis to butterfly, a project that pairs well with a broader look at caterpillar species found in neighboring Georgia, where the same migratory monarchs also pass through.
2. Spicebush Swallowtail Caterpillar
The spicebush swallowtail caterpillar (Papilio troilus) is a master of disguise. Early instars mimic bird droppings, while older larvae turn green or yellow-green with two large, eye-like spots near the head that make the caterpillar look like a tiny snake to startled predators. True to its name, it feeds mainly on spicebush and sassafras, both common understory plants in Louisiana’s hardwood forests.
This defensive mimicry strategy shows up in several other swallowtail species documented in our roundup of caterpillars in Tennessee, where spicebush and sassafras grow alongside similar host plants.
3. Cabbageworm (Imported Cabbageworm)
The imported cabbageworm (Pieris rapae) is a small, velvety green caterpillar with a faint yellow stripe down its back, and it is one of the most persistent pests in Louisiana vegetable gardens. It feeds on cabbage, broccoli, kale, and other brassicas, often chewing ragged holes through leaves while blending in almost perfectly with the foliage. Because it produces several generations each growing season, a single uncontrolled population can strip a garden bed quickly.
Gardeners dealing with this pest alongside other common nuisance insects may find useful context in our broader look at different types of insects that affect home gardens across the region.
4. Milkweed Tussock Caterpillar
The milkweed tussock caterpillar (Euchaetes egle) is covered in dense tufts of black, white, and orange hair-like setae, giving it a punk-rock appearance that stands in sharp contrast to the smooth monarch caterpillars it often shares milkweed plants with. Unlike monarchs, tussock caterpillars feed in groups when young, skeletonizing leaves from the underside before dispersing as they mature. The hairs are irritating to skin for some people, though nowhere near as severe as Louisiana’s true stinging species.
Because it shares host plants with monarchs, gardeners cultivating milkweed for pollinator gardens should expect to see both species, a pattern also noted among the poisonous caterpillars that rely on irritating hairs rather than venomous spines for defense.
5. American Dagger Moth Caterpillar
The American dagger moth caterpillar (Acronicta americana) is pale yellow to white and densely furred, with several longer black “pencil” tufts projecting from its front and rear. It feeds on a wide range of deciduous trees, including oak, maple, and sycamore, making it a common sight on Louisiana shade trees in late summer and fall. While it looks soft and approachable, the fine hairs can cause a mild skin reaction in sensitive individuals.
Similar tussock-family caterpillars with dense fur and defensive hairs also turn up in colder climates, as detailed in our guide to caterpillars found in Wisconsin.
6. Buck Moth Caterpillar
The buck moth caterpillar (Hemileuca maia) is arguably the caterpillar Louisiana residents complain about most. This purple-black caterpillar has a reddish head and small round white spots over its body, with several spiny structures located on each segment of the body. When touched, these spiny structures cause a burning, itching and reddening of the areas stung. Buck moth larvae tend to cluster on branches and move about in a follow-the-leader fashion, and primary hosts include oak, willow, and wild cherry.
In Louisiana, particularly in cities such as Baton Rouge or New Orleans, where use of live oaks as street trees is extensive, the caterpillars can become a significant nuisance for humans. The caterpillars become most troublesome in spring when they descend from oak canopies to pupate in the soil below, dropping onto sidewalks, cars, and unsuspecting pedestrians along the way. Buck moths are not unique to Louisiana — the same species ranges across much of the Gulf South, including the insects documented in Texas.
| Stinging Caterpillar | Peak Season in Louisiana | Sting Severity | Common Host Plants |
|---|---|---|---|
| Buck Moth | March through May | Immediate burning and swelling | Live oak, willow, wild cherry |
| Puss Caterpillar (Asp) | June–July, with a second peak September–October | Severe; may require medical care | Oak, elm, sycamore |
| IO Moth | Summer into fall | Sharp, immediate burning | Wide range of trees and shrubs |
| Saddleback | Summer into fall | Painful welts | Many ornamentals and fruit trees |
| Hag Moth | Summer | Mild to moderate | Oak, hickory, cherry |
7. Puss Caterpillar (Asp Caterpillar)
Few insects in Louisiana cause as much alarm as the puss caterpillar (Megalopyge opercularis), also known as the asp. It looks like a tuft of soft fur, but it is one of the most toxic caterpillars in North America. The asp caterpillar produces two generations a year, leading to a bimodal peak in late spring and late fall, which lines up with reports of New Orleans residents encountering them in both early summer and again in September and October.
Underneath the deceptively soft hair sit venomous spines that trigger intense throbbing pain, burning, and a rash with erythematous spots on contact. In more sensitive individuals, more susceptible patients can experience swelling, nausea, abdominal pain, headache, lymphadenopathy, lymphadenitis, shock, and respiratory distress. Allergies to these stings have been documented, and persons stung should be watched for any potential anaphylactic reaction.
Pro Tip: Never brush a puss caterpillar off with a bare hand. Use a stick, credit card, or piece of tape to lift it away, then wash the area with soap and water before applying a cold compress.
Even after the caterpillar is removed, antihistamines should be taken and a cold compress applied, since the pain can last over 24 hours. For more on how to recognize this species alongside Louisiana’s other venomous larvae, see our dedicated breakdown of caterpillars in Louisiana that sting.
8. IO Moth Caterpillar
The IO moth caterpillar (Automeris io) is hard to miss once you know what to look for. The Io moth forms aggregations like the buck moth caterpillars, but these are typically bright lime green with a white line. Young larvae cluster together on the underside of leaves, moving in loose groups as they feed on a wide variety of host trees and shrubs found throughout Louisiana landscapes.
Despite the bright, almost cheerful coloring, every spine on this caterpillar’s body is loaded with venom that causes immediate stinging pain on contact. These caterpillars turn into vibrant yellow moths by fall, closing out a life cycle that makes them one of the four stinging species Louisiana entomologists flag most often alongside buck moth, puss, and saddleback caterpillars.
9. Saddleback Caterpillar
The saddleback caterpillar (Acharia stimulea) gets its name from the distinctive marking on its back — a green “saddle blanket” with a brown oval “saddle” in the center. The saddleback caterpillar has distinctive coloring, and its stout, slug-like body bristles with fleshy horns at both ends, each tipped with venomous spines. It feeds on a broad range of plants, from ornamental shrubs to fruit trees, making it a common surprise for home gardeners.
A brush against a saddleback caterpillar produces sharp, immediate pain followed by welts that can last for hours. Because it shares garden habitat with several other venomous Louisiana species, homeowners dealing with mixed arthropod concerns may also want to check our guide to spiders found in Louisiana before working barehanded in dense foliage.
10. Hag Moth Caterpillar
The hag moth caterpillar (Phobetron pithecium) is one of the strangest-looking larvae in the state, earning the nickname “monkey slug” for its lobed, hairy appendages that curl outward like tiny tentacles. It feeds on oak, hickory, and cherry trees, and its unusual silhouette — more reminiscent of a piece of dried leaf debris than an insect — helps it avoid predators through simple misdirection.
The fine hairs on a hag moth caterpillar can cause mild to moderate skin irritation, though reactions are generally milder than those from the puss or saddleback caterpillars. Caterpillars with similarly unusual defensive shapes also appear further north, as cataloged in our guide to caterpillars in Connecticut.
11. Tent Caterpillar
Eastern tent caterpillars (Malacosoma americanum) are easy to spot once their communal silk nests appear in the forks of wild cherry and other hardwood branches each spring. The caterpillars themselves are dark with a pale stripe down the back and a row of blue spots along each side, and they emerge from the tent each day to feed before returning at night. Louisiana also hosts the forest tent caterpillar, a close relative that skips the silk tent but can defoliate entire stands of oak and gum trees during outbreak years.
Neither species stings, though heavy infestations can strip trees bare for a season. Gardeners further north dealing with similar seasonal outbreaks can compare notes in our coverage of caterpillars in Iowa.
12. Fall Webworm
The fall webworm (Hyphantria cunea) builds loose, messy silk webs at the ends of branches rather than in the branch forks favored by tent caterpillars. The caterpillars inside are pale yellow-green to nearly white, covered in fine hairs, and feed as a group inside the protection of their web through late summer and fall. They attack a huge range of hardwood trees across Louisiana, including pecan, persimmon, and sweetgum.
Because the caterpillars themselves run pale and fuzzy, homeowners sometimes confuse them with other light-colored larvae. Our guide to white caterpillars helps sort out the look-alikes.
13. Gray Hairstreak Caterpillar
The gray hairstreak caterpillar (Strymon melinus) is a small, slug-shaped larva that ranges from green to brown with faint diagonal stripes, blending easily into the wide variety of plants it feeds on. This species is remarkably unpicky as caterpillars go, feeding on everything from beans and clover to cotton and mallow, which is part of why the adult gray hairstreak butterfly is one of the most widespread hairstreaks in North America.
Its broad host-plant range means it turns up in gardens far beyond Louisiana, including those covered in our look at insects found in Canada, where the species reaches the northern edge of its range.
14. Juniper Hairstreak Caterpillar
The juniper hairstreak caterpillar (Callophrys gryneus) feeds almost exclusively on eastern redcedar and other juniper species, and its green, slightly flattened body is colored and ridged to mimic the scaly foliage it rests on. This camouflage is so effective that the caterpillar is far easier to find by searching cedar branches methodically than by scanning for movement.
Eastern redcedar grows throughout Louisiana’s uplands and fence lines, giving this hairstreak a steady supply of host plants across the state. The same cedar-dependent relationship shows up in populations documented in our guide to caterpillars in Virginia.
15. Striped Hairstreak Caterpillar
The striped hairstreak caterpillar (Satyrium liparops) is a pale green larva with faint white diagonal stripes, closely resembling several other hairstreak species but distinguished by its preference for hawthorn, wild plum, and blueberry as host plants. It is less commonly reported in Louisiana than the gray or juniper hairstreaks, making sightings a modest treat for backyard butterfly watchers.
Because striped hairstreaks share range and habitat with several eastern hairstreak species, comparing populations across states can help with identification — our guide to insects in New York covers the same species near the northern edge of its distribution.
16. Gulf Fritillary Caterpillar
The Gulf fritillary caterpillar (Agraulis vanillae) is bright orange with rows of black branching spines running down its back, a warning coloration that mirrors the toxic alkaloids it absorbs from its sole host plant, passionvine. Louisiana’s warm climate and abundant wild and cultivated passionvine make this one of the more reliably spotted caterpillars in home gardens from spring through fall.
Despite its spiky appearance, the Gulf fritillary caterpillar does not sting; the spines are soft and purely visual deterrents. The species’ range extends well into the tropics, overlapping with related fritillary relatives covered in our look at insects of the Amazon rainforest.
17. Luna Moth Caterpillar
The luna moth caterpillar (Actias luna) is a plump, pale green giant with small reddish-orange spots along its sides and faint rows of tiny spines that look fiercer than they feel. It feeds on a range of Louisiana hardwoods, including sweetgum, hickory, and persimmon, growing to an impressive size before spinning a papery brown cocoon.
Unlike several of the state’s other large caterpillars, the luna moth larva is completely harmless to handle. Its range stretches north into colder climates as well, a pattern explored further in our coverage of caterpillars in Canada.
18. Giant Swallowtail Caterpillar
The giant swallowtail caterpillar (Papilio cresphontes) is often mistaken for bird droppings thanks to its mottled brown and cream coloring, a disguise that works remarkably well against predators scanning citrus leaves for prey. In Louisiana, this caterpillar is a familiar, if sometimes unwelcome, visitor to backyard citrus trees, where it is sometimes called the “orangedog” for its appetite for citrus foliage.
It also feeds on hoptree and prickly ash where citrus isn’t available. The same species ranges west into desert citrus-growing regions, including populations tracked in our guide to caterpillars in Arizona, where giant swallowtails turn up on cultivated citrus in a very different climate.
19. Sphinx Moth Caterpillar
Sphinx moth caterpillars, commonly called hornworms, are instantly recognizable by their thick bodies and the curved horn-like projection at the rear end. The tobacco hornworm (Manduca sexta) is one of the most frequently reported in Louisiana, showing up on tomato, pepper, and tobacco plants where it can strip foliage remarkably fast for its size.
Despite the alarming horn, sphinx moth caterpillars are not venomous and pose no sting risk to humans. Gardeners dealing with hornworm damage alongside other common pests may find it useful to browse our broader survey of different types of insects that affect vegetable gardens.
20. Live Oak Tussock Moth Caterpillar
The live oak tussock moth caterpillar (Orgyia detrita) rounds out this list as another frequent visitor to Louisiana’s signature live oaks. It carries dense tufts of hair-like setae in white, yellow, and black, along with longer “pencil” tufts projecting from the front and rear of its body, a defensive arrangement similar to the American dagger moth but on a smaller scale.
These caterpillars often drop from oak canopies in numbers large enough to be a minor nuisance during peak season, though their sting is far milder than that of the buck moth caterpillars they frequently share trees with. Anyone cataloging the full range of small arthropods living in Louisiana’s oak canopies may also want to check our guide to spiders found in Louisiana, since several web-building species favor the same branches.
Final Thoughts on Louisiana’s Caterpillars
From the harmless monarch munching milkweed in a backyard garden to the buck moth caterpillar waiting to drop from a live oak overhead, Louisiana’s caterpillar population reflects the state’s humid climate and dense mix of native trees, shrubs, and wildflowers. Most species, including every butterfly caterpillar on this list, are completely safe to observe up close. The handful of stinging species — buck moth, puss, IO moth, saddleback, and hag moth — are the exceptions worth remembering before reaching out to touch anything fuzzy or spiny.
Whether you are trying to identify a caterpillar on a porch screen or planning a pollinator garden to attract more of them, a little knowledge goes a long way toward enjoying Louisiana’s insect life safely.