A guide to help you identify 20 common types of caterpillars in Maryland, what they look like, where you can find them, and whether or not they’re harmful to plants.
All photos and information come from Maryland Extension Service publications, which are accurate and up-to-date!
Keep reading if you live in Maryland and want to learn more about caterpillars. You’ll learn how to identify the different types of caterpillars living here, their scientific names, lifecycles, and feeding preferences.
1. Monarch Caterpillar
The monarch caterpillar, or Danaus plexippus, is a beautiful orange caterpillar covered with black spots.
These types of caterpillars in Maryland have a large black dot at each segment near their head. Monarch caterpillars feed on milkweed plants.
The pupae turn into monarch butterflies that favoriting thousands of miles yearly bet America and Mexico. These butterflies may use your garden as their stopping point on their migration route!
If you want to keep monarchs coming back every year, leave some milkweed plants unharvested during fall so they can find them for shelter over winter.
Once spring arrives, your garden will be full of monarch caterpillars looking for a place to grow into adult butterflies.
The cabbage butterfly or cabbage worm (Pieris rapae) is probably one of the most commonly identified types of caterpillars in Maryland.
Cabbage worms are best identified by their white-colored stripes along either side, black dots scattered randomly, little ‘horns’ on their back end, and redhead.
Common host plants for cabbage worms include members from both family Brassicaceae (cabbages, Brussel sprouts, turnips) and Solanaceae (tomatoes), along with others such as brassicas (radish).
Heavy infestations can destroy a crop or ruin all leaves on a plant due to feeding damage caused by defoliation.
3. Woolly Bear
Woolly Bear caterpillars are large types of caterpillars in Maryland. They are hairy, green caterpillars with two pairs of fleshy spines along each side. The one pictured is ready to pupate; notice how it is beginning to remove its old skin.
That’s a good sign that it will soon spin a chrysalis. While these guys may look scary, they pose no harm whatsoever to humans or plants. You can help Woolly Bear thrive by planting milkweed (also known as Asclepias spp.).
Milkweed makes up about ninety percent of a monarch’s diet during both stages of its life cycle—as an egg and as a larva. Planting multiple varieties helps provide more nectar for adult monarchs, too!
4. Viceroy Caterpillar
The larvae are black with a yellow V-shaped mark on each side, giving them their name. This is a non-native species found throughout North America.
The adults mimic Monarch butterflies and lay eggs on milkweed plants; however, they are toxic to Monarch caterpillars.
If you spot Viceroy butterflies, note that they have no yellow markings on their wings. Instead, they have orange spots near their wingtips. There is only one generation per year.
5. Large Maple Spanworm
While they may look like moths or small butterflies, hornworms are caterpillars. These types of caterpillars in Maryland are green with red stripes on their backs, though they can also appear brownish or black. Their heads are narrow and have small horns sticking out from them.
Hornworms get their name from having bright orange horns at either end of their abdomens that look similar to those found on certain types of moths (though these horns don’t sting).
When mature, hornworms eat leaves almost exclusively but can sometimes devour whole fruits before hatching into adult moths.
6. Variegated Fritillary Caterpillar
The variegated fritillary is one of many caterpillar species that camouflage themselves by mimicking leaves. This one is hard to identify because it has no legs, but if you touch its body, it will curl itself into a ball.
So it’s probably best to avoid touching these, though variegated fritillaries are poisonous. Its body is green and black with white zigzags.
You’ll find them throughout most of Maryland from June through August, feeding on violets, dandelions, clover, phlox, and other wildflowers.
Plant more native flowers like goldenrod, milkweed, and Queen Anne’s lace to attract more butterflies.
These types of caterpillars in Maryland also like coneflower (Echinacea), buttonbush (Cephalanthus occidentalis), and butterfly bush (Buddleia davidii). Variegated fritillaries lay their eggs on or near violets; they eat violet leaves when they hatch.
7. Curve-Lined Owlet Moth Caterpillar
The Curve-Lined Owlet Moth caterpillar, also known as Hemeroplanes rubricaudalis, is a species of moth that belongs to several different genera depending on taxonomic views.
They are found throughout North America, a fairly common species in Maryland. These types of caterpillars in Maryland have some very distinct markings, including bright red coloring near their head and black spots that start at their head and then curve down along their abdomen.
You will also find similar bands down their sides with another set towards their back end. The larvae themselves grow up to be owlets, which are nocturnal moths with reddish or orange eyespot patterns on them.
Hornworms are a type of caterpillar that feed on your tomato plants. These types of caterpillars in Maryland can be identified by their brown color, though some green varieties exist.
In addition, the hornworm has several black stripes running down its body and a protruding horn on its head.
Like many types of caterpillars in Maryland, hornworms are somewhat defensive and curl up into a ball when they feel threatened.
Knowing these characteristics is important if you’re wondering how to get rid of a hornworm infestation. After identifying your pest, use Bacillus thuringiensis (BT) spray.
9. White-Marked Tussock Caterpillar
The White-Marked Tussock Moth (Lophocampa argentata) is iconic in most of North America. However, in Maryland, these types of caterpillars in Maryland are commonly found on their host plant, smooth buttonbush. The wingspan can reach up to 4 inches.
The White-Marked Tussock Moth has green forewings with white markings towards the tip and a red mark near its center. Its hindwings are orange with black spots at their tips.
Small tufts called tussocks appear at both ends of each segment along its body except for segments 3 through 5; these tussocks may become erect when threatened or disturbed.
10. Milkweed Tussock Caterpillar
These types of caterpillars in Maryland are yellowish-white with dark brown markings, but because they are covered in white hairs, it can be hard to see them at first glance.
These types of caterpillars in Maryland feed on milkweed, which explains their name. As they munch on their favorite plants, they produce venomous spines that stick to anything or anyone that tries to eat them.
This means that even when these caterpillars are dead (which occurs after 2–3 weeks), their bodies remain covered in poison-tipped bristles that can still cause harm—it’s not recommended you touch these little guys without gloves or tongs.
11. Banded Tussock Caterpillar
The banded Tussock Caterpillar is a medium-sized moth native to North America. The caterpillar, the family Lasiocampidae, grows up to 3.5 centimeters long.
It has a pink body with bright yellow stripes running down its side with black legs and pincers. When alarmed, it makes a hissing noise by rubbing two parts together like a snake.
In addition, the Banded Tussock caterpillar feeds on trees belonging to various plant families, such as the Beech family, Maple family, and Chestnut family, among others which includes linden(lime), basswood (linden), and poplar(birch). Both larvae and adults are active from March to May, depending on location.
12. Giant Leopard Moth Caterpillar
The Giant Leopard Moth (Hypercompe scribonia) is a tiger moth species. It is found across most of North America, south into Central America.
These types of caterpillars in Maryland are particularly common from Nova Scotia west to British Columbia and south through New England, Michigan, and Ohio into northern Georgia.
A member of its genus Hypercompe, it was at one time called Megalopyge. It generally resembles several other species (especially Hypercompe albicornis). However, its forewing has a prominent tuft at its base and three white spots along its margin.
These types of caterpillars in Maryland will readily identify them if seen. Its habitat consists mainly of moist woodlands throughout North America. The wingspan is 80–120 mm.
13. Parsley Caterpillar
Parsley Caterpillar (Black Swallowtail) adults are a major pest on parsley, carrot, celery, dill, fennel, lovage, parsnip, and Queen Anne’s lace.
Adult populations may be destroyed by picking them off crops and placing them in a container filled with soapy water or kerosene.
Eggs are laid on leaves and, when fully grown, resemble bird droppings. The tiny yellowish-orange caterpillar (1/4 inch long) feeds at night on foliage.
A single female can lay up to 400 eggs during its life span, which lasts up to eight weeks. These types of caterpillars in Maryland feed on most herbaceous plants, including asparagus, beans, cabbage, corn, lettuce, and tomato. Control is usually unnecessary since there are usually only one or two generations per year.
14. Eastern Tiger Swallowtail Caterpillar
The Eastern Tiger Swallowtail Caterpillar is found throughout most of North America. It is easy to identify because it has a black head with bright green dots. However, its wings are orange with black stripes when it becomes an adult butterfly.
To avoid predation, a caterpillar will play dead when humans touch or pick them up. If you find one that isn’t moving, be sure not to disturb them because it may come alive at any moment!
The Eastern Tiger Swallowtail Caterpillar eats Black Cherry trees and Milkweed plants. You can help save their population by planting these two types of plants if you’d like!
15. Spicebush Swallowtail Caterpillar
Spicebush Swallowtail Caterpillar (Papilio Troilus) lives on flowering spicebushes, red cedar, alder, and sassafras.
The larvae feed on leaves for about a month before constructing a large portable cocoon made from silk-wrapped twigs from its host plant.
Mature caterpillars have four yellow spots on their body, which looks like a large bird dropping to dissuade predators. It takes three months and two years for Spicebush Swallowtail caterpillars to mature into adult butterflies.
16. Cecropia Moth Caterpillar
The cecropia moth caterpillar, also called an elephant trunk caterpillar, is found throughout North America and parts of South America.
The larvae are lime green with a pale yellow band around their middle. As they grow larger, they turn dark green, retaining their yellow band until they form their cocoon.
On its back are rows of purplish-blue spots that give it its Latin name: cecropia. Cecropia caterpillars feed on maple trees and can reach up to 3 inches (7.6 cm) long when mature.
These types of caterpillars in Maryland molt five times during their life cycle before entering their cocoon stage for about two weeks before emerging as a moth.
17. Monkey Slug
The monkey slug is a species of air-breathing land slug, a terrestrial pulmonate gastropod mollusk in the family Veronicellidae.
This slug species has a shiny black body with white spots on its back. It also has two small red eyes that sit on a retractable head that can move from side-to-side, up and down.
This slug species can grow up to 8 inches long. However, it is often shorter than 5 inches. Monkey slugs are nocturnal creatures and feed on snails, earthworms, insects, plant matter, and other slugs.
Monkey slugs are commonly found throughout Maryland along streams and around wetland areas, where they spend most of their time under logs or rocks to avoid being eaten by predators like frogs or birds.
These types of caterpillars in Maryland are hermaphroditic, meaning they have both male and female reproductive organs allowing them to self-fertilize if necessary.
18. Spotted Apatelodes Caterpillar
While Apatelodes caterpillars are known as fritillary caterpillars, they are not fritillaries. Rather, they look like fritillaries.
These types of caterpillars in Maryland feature a white body with dark spots on each side of their body that resemble eyes; all fritillaries have eyespots, but Apatelodes spot only has them on its back end.
Like most sphinx moth caterpillars, they eat leaves from willow trees (not just birch trees) during their larval stage. In Theyefer, poplar (Eastern cottonwood) over willow trees by a lot.
19. Io Caterpillar
The Io caterpillar has a blue body, yellow legs, black eyes, red spiracles (tiny holes where they breathe), a black-and-red stripe on each side of its body (look like upside-down exclamation points), and tufts or horns on each side of its head. The horn is an orange head that covers up another breathing hole.
The Io feeds on various types of trees, including willow, ash, apple, poplar, oak, hickory, and hawthorn. You can find them during spring in meadows or along streams.
In summer, it hides under leaves, entering its pupal stage for 3–4 weeks before emerging as a moth about 2 1/2 inches long with grayish wings covered with small bumps.
20. Flannel Moth Caterpillar (Asp)
The Flannel Moth caterpillar (also known as a Hornworm) is one of 20 types of caterpillars in Maryland. It has a single, large eye spot on its back side.
In addition, the caterpillar has reddish-brown mottled stripes along its body and chocolate-brown heads with orange jaws.
The most distinguishing feature is its velvety flannel skin. These types of caterpillars in Maryland are present from early summer to late fall, feeding on leaves and occasionally flowers (Pennsylvania).
This month does not create cocoons; instead, it pupates directly within their last larval skin, which turns brown when they finish growing.
Did you know there were so many different types of caterpillars in Maryland in your state? As an entomologist, I am always intrigued by them.
Each is unique, with its colors, structures, and patterns. Some caterpillars even have tufts on their head that stick up like a Mohawk!
Not all caterpillar species become butterflies or moths. Some will turn into wasps, beetles, or flies. So, if you ever see a weird-looking caterpillar that catches your eye, snap a picture and send it our way! It will be fun for us to figure out what kind it is.
Thank you for reading! We hope everyone who reads our post has a great time learning about different caterpillar species found in Maryland.