When you spot a mysterious caterpillar crawling across your garden path or munching on your prized plants, you’re witnessing one of nature’s most remarkable transformation stories in progress.
Delaware hosts an incredible diversity of caterpillars in Delaware, from the iconic striped Monarch larvae to the fuzzy Woolly Bears that signal changing seasons.
Whether you’re a curious gardener, nature enthusiast, or simply want to know what’s living in your backyard, this comprehensive guide will help you identify the 25 most common species you’ll encounter throughout the First State.
Understanding these fascinating larvae isn’t just about satisfying curiosity—it’s about appreciating the vital role they play in Delaware’s ecosystem. These future butterflies and moths serve as essential pollinators, provide crucial protein for songbirds, and indicate the health of our local environment.
Some species you’ll want to protect and encourage, while others might require gentle management in your garden spaces.
1. Forest Tent Caterpillar
The Forest Tent caterpillar presents a distinctive appearance with its blue body decorated with white keyhole-shaped spots along the back. Despite its name, this species doesn’t actually build tents like its Eastern Tent caterpillar relatives.
Forest Tent caterpillars (Malacosoma disstria) emerge in late spring when oak, maple, and cherry trees begin leafing out. You’ll find them creating silk mats on tree trunks and branches rather than enclosed tents. These gregarious feeders can cause significant defoliation during outbreak years, though healthy trees typically recover.
Key Insight: Forest Tent caterpillars are cyclical pests that experience population booms roughly every 10 years, making them more noticeable during certain seasons.
Look for them crawling in long processions between feeding sites, often traveling considerable distances to find suitable pupation spots. Their feeding damage appears as partially consumed leaves with only the main veins remaining.
2. Gypsy Moth Caterpillar (Spongy Moth)
The Gypsy Moth caterpillar, recently renamed Spongy Moth (Lymantria dispar), ranks among Delaware’s most concerning invasive species. These hairy larvae display distinctive blue and red spots along their gray-brown bodies, making them relatively easy to identify.
Young larvae prefer oak leaves but become less selective as they mature, eventually feeding on over 300 plant species. The caterpillars are most active during nighttime hours, climbing down trees during daylight to hide in bark crevices and leaf litter.
Important Note: Spongy Moth caterpillars can cause severe allergic reactions in sensitive individuals due to their irritating hairs, so avoid direct contact.
Female moths lay tan, fuzzy egg masses on tree trunks, outdoor furniture, and vehicles, which can inadvertently spread the species to new areas. Early detection and removal of egg masses provides the most effective control method.
3. Luna Moth Caterpillar
Luna Moth caterpillars (Actias luna) transform Delaware’s woodlands into scenes from a fairy tale with their impressive size and striking green coloration. These chunky, lime-green larvae can reach four inches in length and sport small orange spots along their sides.
You’ll find Luna caterpillars feeding on walnut, hickory, sweetgum, and birch trees from June through August. Their feeding typically doesn’t cause noticeable damage to healthy trees since they maintain relatively low population densities.
Pro Tip: Luna caterpillars change color as they prepare to pupate, shifting from bright green to a reddish-brown hue before spinning their papery cocoons.
The species produces one generation per year in Delaware’s climate, with adults emerging in late spring. Luna caterpillars are considered beneficial since the adult moths serve as important pollinators and provide food for bats and other nocturnal predators.
4. Monarch Caterpillar
The Monarch caterpillar stands as one of Delaware’s most recognizable larvae, featuring distinctive black, white, and yellow stripes with prominent black tentacles. These iconic caterpillars exclusively feed on milkweed plants, making them easy to locate if you know where to look.
Monarch caterpillars (Danaus plexippus) accumulate toxins from their milkweed diet, making them unpalatable to most predators. Their bold coloration serves as a warning signal to potential threats. Finding these colorful insects on milkweed plants offers an excellent opportunity to observe their remarkable transformation into adult butterflies.
Delaware supports multiple generations of Monarchs each year, with the final generation undertaking an extraordinary migration to Mexico. Creating milkweed habitat in your garden directly supports this iconic species and their incredible journey.
Common Mistake: Never relocate Monarch caterpillars far from their original location, as this can disrupt their natural navigation abilities and migration patterns.
The species faces significant conservation challenges due to habitat loss, making every milkweed plant in Delaware valuable for their survival.
5. Black Swallowtail Caterpillar
Black Swallowtail caterpillars (Papilio polyxenes) undergo dramatic transformations throughout their development. Early instars appear as tiny black caterpillars with white bands, eventually becoming large green larvae decorated with black stripes and orange spots.
These adaptable feeders target plants in the carrot family, including garden herbs like parsley, dill, and fennel. You might also discover them on wild Queen Anne’s lace growing along roadsides and field edges.
Black Swallowtail larvae possess a defensive mechanism called an osmeterium—a bright orange, fork-shaped organ they can extend from behind their head when threatened. This startling display often deters predators and curious humans alike.
Garden Integration Tips:
- Plant extra parsley and dill to share with these beautiful caterpillars
- Allow some Queen Anne’s lace to grow in wilder garden areas
- Position host plants near nectar sources for adult butterflies
The species produces two to three generations annually in Delaware, with overwintering occurring in the pupal stage.
6. Tiger Swallowtail Caterpillar
Tiger Swallowtail caterpillars demonstrate remarkable adaptability by feeding on various tree species throughout Delaware. These impressive larvae start small and green but develop into chunky, smooth caterpillars with prominent false eyespots.
Eastern Tiger Swallowtail caterpillars (Papilio glaucus) prefer cherry, tulip poplar, ash, and cottonwood trees. During daylight hours, the caterpillars use silk to wrap themselves in leaves for protection, making them challenging to spot during casual observation.
The eyespots serve as an effective predator deterrent, making the caterpillar appear larger and more threatening than it actually is. When disturbed, they can also extend their osmeterium for additional protection.
Seasonal Timing: Look for Tiger Swallowtail caterpillars from late spring through early fall, with peak numbers occurring during mid-summer months.
Before pupating, the caterpillars change from green to brown coloration and purge their digestive systems, leaving behind noticeable watery deposits that can help locate pupation sites.
7. Spicebush Swallowtail Caterpillar
Spicebush Swallowtail caterpillars (Papilio troilus) master the art of disguise throughout their development. Young larvae mimic bird droppings with their brown and white mottled appearance, while mature caterpillars develop into smooth, green individuals with prominent yellow-ringed eyespots.
The distinctive caterpillars prefer white sassafras and spicebush plants, which contributed to their common name. They also accept bay laurel and other plants in the laurel family when their preferred hosts aren’t available.
These caterpillars create individual leaf shelters by folding leaves and securing them with silk. Inside these protective enclosures, they feed safely during the day and molt between instars.
Habitat Preferences:
- Woodland edges with dappled sunlight
- Areas near streams and moist soils
- Native plant gardens featuring spicebush
- Suburban landscapes with mature trees
Spicebush Swallowtails possess unique thermal regulation abilities, allowing them to remain active at cooler temperatures compared to other swallowtail species in Delaware.
8. Pipevine Swallowtail Caterpillar
Pipevine Swallowtail caterpillars (Battus philenor) represent one of Delaware’s most toxic species, accumulating dangerous alkaloids from their host plants. These dark caterpillars feature rows of orange-red tubercles along their black bodies, advertising their unpalatable nature to potential predators.
The species specifically targets Dutchman’s pipe (Aristolochia) and related vines, though these native plants are becoming increasingly rare in Delaware’s landscape. Conservation efforts often focus on protecting and establishing pipevine populations to support these specialized butterflies.
Pipevine Swallowtail caterpillars feed communally when young, creating obvious feeding damage on their host vines. As they mature, they become more solitary and can strip entire vine sections of foliage.
Conservation Status: Pipevine Swallowtails are considered uncommon in Delaware due to limited host plant availability, making any sighting noteworthy for local naturalists.
The toxicity acquired during the larval stage persists through metamorphosis, making adult Pipevine Swallowtails unpalatable as well. Several other butterfly species have evolved to mimic their warning coloration.
9. Painted Lady Caterpillar
Painted Lady caterpillars display variable coloration ranging from greenish-yellow to charcoal, with most individuals featuring light-colored spots scattered across their bodies. These adaptable feeders accept an remarkably wide range of host plants.
Painted Lady caterpillars (Vanessa cardui) commonly feed on thistles, mallows, legumes, and many garden plants. Their catholic tastes allow them to thrive in diverse habitats from wild fields to suburban gardens.
Population numbers can vary dramatically from year to year, with some seasons producing massive migrations while other years see very few individuals. This natural fluctuation reflects their complex migration patterns and weather sensitivities.
Individual caterpillars create silk webbing shelters on their host plants, often incorporating plant debris for camouflage. These shelters provide protection during molting and adverse weather conditions.
Migration Marvel: Painted Lady butterflies undertake multi-generational migrations spanning continents, making them one of the world’s most widely distributed butterfly species.
10. Red Admiral Caterpillar
Red Admiral caterpillars appear pinkish-gray to charcoal with distinctive white spots and hair-like spines along their backs. These solitary feeders specialize on stinging nettle plants, making them relatively easy to locate when you know their preferred habitat.
Red Admiral caterpillars (Vanessa atalanta) construct silk shelters by folding nettle leaves and securing them with webbing. Inside these protective enclosures, they feed safely while avoiding predators and harsh weather.
Look for Red Admiral butterflies near forest edges in moist habitats where nettles naturally grow. The adults show remarkable tameness around humans and frequently land on people, making them excellent subjects for close observation.
Ecological Benefits:
- Help control nettle populations in natural areas
- Provide protein for birds and small mammals
- Adult butterflies serve as pollinators for various flowers
- Indicate healthy wetland and woodland edge habitats
Red Admirals are migratory butterflies that move south during winter and return north in late spring when food sources become abundant.
11. Mourning Cloak Caterpillar
Mourning Cloak caterpillars (Nymphalis antiopa) congregate in large groups on willow, elm, and poplar trees, creating impressive feeding displays during peak summer months. These spiny, black caterpillars feature rows of red spots along their backs and can quickly defoliate small branches.
The gregarious feeding behavior serves multiple purposes: it overwhelms plant defenses, provides safety in numbers, and allows efficient processing of tough tree leaves. Groups can contain dozens of individuals working together to strip foliage.
Mourning Cloak caterpillars possess urticating hairs that can cause skin irritation in sensitive individuals. Handle them carefully if removal becomes necessary, and always wear gloves during management activities.
Unique Life Cycle: Unlike most butterflies, Mourning Cloaks overwinter as adults, hiding in tree cavities and other protected locations throughout Delaware’s cold months.
Adult Mourning Cloaks rank among the longest-lived butterflies in North America, potentially surviving nearly a full year from emergence to death.
12. Cabbage White Caterpillar
In Delaware, Cabbage White caterpillars are often called Imported Cabbageworms because they’re not native to North America. These velvety, light green larvae with small yellow dots can cause severe damage to brassica crops and garden plants.
Cabbageworms rank among the most destructive garden pests due to their voracious eating habits, easily skeletonizing entire plants by consuming everything except the toughest stems and midveins. They readily attack cabbage, broccoli, cauliflower, and related crops.
Integrated Management Approach:
- Regular monitoring and early detection
- Row covers during peak egg-laying periods
- Beneficial insect habitat to support natural enemies
- Crop rotation to disrupt life cycles
- Hand-picking when populations are manageable
For home gardeners, preventing large infestations through plant covers, regular weeding, and diverse plantings provides the most effective long-term control.
13. Woolly Bear Caterpillar
Woolly Bear caterpillars display distinctive black coloration with a wide rusty-red band around their middle, and their bodies are covered in dense, coarse hairs. These hardy caterpillars eventually transform into Isabella Tiger Moths.
Woolly Bears function as generalist feeders, accepting nearly any plant species they encounter. This adaptability allows them to thrive in diverse habitats from wild meadows to suburban lawns.
Folk Weather Prediction: While popular folklore suggests Woolly Bear band patterns predict winter severity, scientific evidence doesn’t support this charming belief. The bands reflect the caterpillar’s age and nutrition rather than future weather patterns.
These caterpillars possess remarkable cold tolerance, surviving freezing temperatures by producing natural antifreeze compounds. They may take two years to complete development in Delaware’s climate, overwintering twice before pupating.
Woolly Bears actively search for pupation sites during late fall, often crossing roads and sidewalks in their quest for suitable locations.
14. Yellow Woolly Bear Caterpillar
Yellow Woolly Bear caterpillars (Spilosoma virginica) sport dense, pale yellow to cream-colored fuzzy coats that distinguish them from their more famous Isabella relatives. These adaptable feeders accept an enormous variety of plants, from garden vegetables to wild weeds.
The caterpillars remain active later into fall than most species, often continuing to feed until hard freezes arrive. Their thick hair provides excellent insulation against Delaware’s variable autumn weather.
Yellow Woolly Bears produce two generations annually in favorable years, with the second generation overwintering as pupae. Spring emergence timing depends on accumulated heat units and soil temperature.
Garden Considerations:
- Generally beneficial as adults are important pollinators
- Feeding damage is usually minimal and scattered
- Prefer wild plants over cultivated garden crops
- Support birds and other wildlife as protein sources
Adult Virginia Tiger Moths emerge as pure white, medium-sized moths that visit night-blooming flowers and serve as important nocturnal pollinators.
15. Eastern Tent Caterpillar
Eastern Tent caterpillars (Malacosoma americanum) construct distinctive silk tents in the crotches of cherry, apple, and related trees. These social caterpillars create communal shelters where they retreat during bad weather and nighttime hours.
The caterpillars emerge from their tents to feed on surrounding foliage, following silk trails laid down by scouts. This cooperative behavior allows efficient exploitation of food resources while maintaining group cohesion.
Eastern Tent caterpillars have been linked to mare reproductive loss syndrome in horses, causing miscarriages and stillbirths when pregnant mares accidentally ingest the caterpillars.
Management Recommendations:
- Remove tents during cool morning hours when caterpillars are inside
- Prune out egg masses during winter tree maintenance
- Encourage natural predators like birds and beneficial insects
- Use biological controls like Bt if necessary
Tent caterpillar populations follow natural cycles, with outbreak years followed by several years of low numbers as natural controls reassert themselves.
16. Polyphemus Moth Caterpillar
Polyphemus Moth caterpillars appear in Delaware during June and again from August through September, feeding on oak, hickory, elm, maple, and other deciduous trees. These impressive green larvae can reach four inches in length and feature prominent red tubercles.
The caterpillars feed individually rather than in groups, typically causing minimal damage to healthy trees. Their feeding creates small holes in leaves but rarely results in significant defoliation.
Planting oak trees provides one of the most effective ways to support insect biodiversity, with even small specimens supporting numerous Lepidoptera species in the landscape.
Polyphemus caterpillars undergo five instars before pupating, growing dramatically in size with each molt. The final instar caterpillars actively search for suitable pupation sites, often appearing far from their host trees.
Important Note: Polyphemus Moths rank among North America’s largest native silk moths, with adult wingspans reaching six inches across.
17. Cecropia Moth Caterpillar
Cecropia Moth caterpillars (Hyalophora cecropia) represent Delaware’s largest native caterpillar species, reaching lengths of four to five inches at maturity. These spectacular larvae feature turquoise bodies decorated with coral-colored tubercles tipped in black.
The caterpillars feed on various deciduous trees including maple, cherry, apple, and lilac. Young larvae prefer tender new growth, while mature caterpillars can handle tougher, older leaves with ease.
Cecropia caterpillars change dramatically in appearance throughout their development. Early instars appear black and spiny, gradually developing their characteristic coloration and smooth texture through successive molts.
Habitat Requirements:
- Mixed deciduous woodlands with diverse tree species
- Suburban areas with mature shade trees
- Parks and natural areas with minimal pesticide use
- Gardens featuring native woody plants
Adult Cecropia Moths emerge without functional mouthparts and live only long enough to mate and reproduce, making the caterpillar stage crucial for accumulating energy reserves.
18. Io Moth Caterpillar
Io Moth caterpillars (Automeris io) pack a powerful defensive punch with their venomous spines that can cause painful, long-lasting stings. These pale green caterpillars feature distinctive red and white stripes along their sides and clusters of branched spines.
The caterpillars feed on diverse plants including corn, roses, willows, and many garden species. Despite their intimidating appearance, they rarely cause significant plant damage due to their typically low population densities.
Safety Warning: Io caterpillar stings can cause severe pain, swelling, and allergic reactions. The effects may persist for several hours and can require medical attention in sensitive individuals.
Young Io caterpillars feed gregariously, but older larvae become solitary as they approach pupation. The gregarious phase provides safety in numbers while the later solitary behavior reduces intraspecific competition.
Adult Io Moths display dramatic sexual dimorphism, with males showing bright yellow wings and females exhibiting subdued brown coloration for camouflage during egg-laying activities.
19. American Dagger Moth Caterpillar
American Dagger Moth caterpillars (Acronicta americana) sport dense yellow fur interrupted by distinctive black “pencils” or tufts of longer hairs. These eye-catching larvae feed on various deciduous trees including maple, oak, elm, and poplar.
The caterpillars prefer feeding on tree leaves rather than herbaceous plants, making them more common in wooded areas and mature landscapes. Their feeding typically doesn’t cause noticeable damage to healthy trees.
Handling Precautions: The dense hairs can cause skin irritation and allergic reactions in sensitive individuals, similar to other fuzzy caterpillar species.
American Dagger caterpillars often rest on tree trunks during daylight hours, relying on their cryptic coloration to avoid detection by predators. Their fuzzy appearance helps break up their outline against bark surfaces.
The species produces one generation annually in Delaware, with caterpillars most commonly encountered during late summer and early fall months.
20. Hickory Tussock Moth Caterpillar
Hickory Tussock Moth caterpillars (Lophocampa caryae) display striking white fuzzy bodies accented with black tufts along their backs. These attractive larvae specialize on hickory, walnut, and related trees throughout Delaware’s woodlands.
The caterpillars feed in groups when young, creating noticeable feeding damage on hickory branches. As they mature, they become more dispersed and cause less concentrated defoliation.
Identification Features:
- Dense white body hairs with black tufts
- Prominent black head capsule
- Length of 1.5 to 2 inches when mature
- Distinctive “bottle brush” appearance
The urticating hairs can cause skin irritation and dermatitis in sensitive individuals. Avoid direct contact and handle with gloves if removal becomes necessary.
Hickory Tussock caterpillars overwinter as pupae in thin cocoons constructed from body hairs and silk, typically hidden under loose bark or in leaf litter.
21. Giant Leopard Moth Caterpillar
Giant Leopard Moth caterpillars, commonly called Woolly Worms (Hypercompe scribonia), feature jet-black fuzzy bodies with red bands between their segments. These impressive caterpillars can reach three inches in length and curl into defensive balls when threatened.
The species accepts an enormous variety of host plants, from garden vegetables to wild broadleaf weeds. This adaptability allows them to thrive in diverse habitats throughout Delaware.
Giant Leopard caterpillars remain active well into autumn, often continuing to feed until the first hard freezes. Their excellent cold tolerance allows extended feeding seasons compared to most species.
Defensive Behavior: When disturbed, these caterpillars curl into tight balls and remain motionless, a behavior called thanatosis or “playing dead.”
The adult moths display stunning white wings covered with black leopard-like spots, creating some of Delaware’s most beautiful large moths.
22. White-lined Sphinx Caterpillar
White-lined Sphinx caterpillars (Hyles lineata) come in two distinct color forms: bright green with yellow stripes or black with yellow markings. Both forms feature prominent horn-like tails characteristic of sphinx moth larvae.
These robust caterpillars feed on various plants including evening primrose, grape, tomato, and many garden species. Their feeding can occasionally cause noticeable damage to cultivated plants, especially during outbreak years.
Remarkable Migration: White-lined Sphinx moths undertake impressive migrations, sometimes appearing in Delaware in large numbers during favorable weather conditions.
The caterpillars burrow into soil to pupate, creating underground chambers where they transform into adults. This behavior makes them less visible during their vulnerable pupal stage.
Adults emerge as powerful flying moths with distinctive white lines across their forewings, earning them the nickname “hummingbird moths” for their hovering flight patterns.
23. Hummingbird Clearwing Caterpillar
Hummingbird Clearwing caterpillars find their preferred host in possumhaw viburnum, which grows commonly in Delaware’s woodland areas. These green hornworms feature white diagonal stripes and the characteristic tail spine of sphinx moth larvae.
The caterpillars also accept other viburnum species and occasionally feed on honeysuckle and related plants. Their feeding rarely causes significant damage to healthy shrubs.
Hummingbird Clearwing caterpillars pupate in underground chambers, emerging as day-flying moths that closely mimic hummingbirds in flight. This remarkable mimicry helps protect them from predators that avoid the aggressive territorial behavior of actual hummingbirds.
Conservation Note: Delaware’s woodlands have declined to only 23% of their original area, making habitat conservation crucial for woodland-dependent species like this moth.
The adult moths visit flowers during daylight hours, serving as important pollinators for various native plants throughout Delaware’s remaining natural areas.
24. Buckeye Caterpillar
Buckeye caterpillars appear dark brown to black with distinctive stripes along their backs and sides, plus spines covering their entire bodies. These spiky larvae feed on plantain, snapdragon, and other plants in open, sunny locations.
Common Buckeye caterpillars (Junonia coenia) prefer disturbed habitats like roadsides, old fields, and garden edges where their host plants naturally establish. They’re often found in areas that might be considered “weedy” by traditional gardening standards.
The butterflies prefer open spaces like pastures and old fields throughout Delaware, flying low to the ground and remaining wary of predators.
The caterpillars feed individually rather than in groups, typically causing minimal damage to their host plants. Their spiny appearance provides effective protection against most predators.
Breeding Strategy: In northern states like Delaware, Common Buckeyes migrate south for winter and return in spring for mating, producing two to four generations each season.
25. Viceroy Caterpillar
Viceroy caterpillars (Limenitis archippus) display mottled brown and cream coloration that provides excellent camouflage against willow and poplar bark. These masters of disguise also feature distinctive horn-like projections behind their heads.
The caterpillars construct individual shelters called hibernacula by rolling leaves and securing them with silk. They use these shelters for protection during molting and overwintering, depending on the generation.
Viceroy caterpillars feed exclusively on willow and poplar trees, making them relatively easy to locate in appropriate habitats. Their feeding creates characteristic notched patterns along leaf edges.
Mimicry Marvel: Adult Viceroy butterflies famously mimic Monarch butterflies, gaining protection through their resemblance to the toxic species even though Viceroys are palatable.
The species produces multiple generations annually in Delaware, with different broods employing varying overwintering strategies depending on seasonal timing.
Conclusion
Delaware’s diverse caterpillar community reflects the state’s rich ecological heritage and varied habitats. From the iconic Monarch larvae that depend on native milkweeds to the spectacular sphinx moth caterpillars that transform into powerful night-flying adults, each species plays a crucial role in maintaining healthy ecosystem balance.
Key Takeaways: Understanding caterpillar identification helps you make informed decisions about garden management, supports conservation efforts for declining species, and deepens your appreciation for the complex web of life surrounding us. Many of these caterpillars face challenges from habitat loss, climate change, and pesticide use, making your backyard habitat choices increasingly important for their survival.
Creating caterpillar-friendly spaces doesn’t require extensive effort—simply reducing pesticide use, planting native host plants, and tolerating minor feeding damage can significantly impact local populations.
Whether you’re observing a fuzzy Woolly Bear crossing your path or discovering a magnificent Cecropia caterpillar on your maple tree, you’re witnessing one of nature’s most incredible transformation stories in progress.
