What kinds of caterpillars can you find in Arizona?
Caterpillars are some of the MOST fascinating insects in the world! It always amazes me that caterpillars eventually turn into butterflies or moths.
There are hundreds of different caterpillar species found in Arizona!
Since it would be impossible to list them all in one article, I chose the 23 most interesting and common ones to share with you. 🙂
#1. Monarch Caterpillar
- Danaus plexippus
- This famous caterpillar is plump with black, white, and yellow bands.
- Its legs and pro-legs are pronounced, and each end of its body has spindly black tentacles.
- The Monarch’s preferred host plant is milkweed.
Like the adult butterfly, the Monarch is one of the most well-recognized caterpillars in Arizona!
Their distinctive stripes and tentacles make them look cartoonish. But this highly visible coloring sends a message to predators: Back Off!
Monarch Caterpillars are toxic to most animals, and at the very least, taste bad! This poison comes from their diet, which is almost entirely made up of milkweed. Toxins from the milkweed plant stay in the caterpillar, producing a bitter taste and poisonous effects.
If you have milkweed in your yard or nearby, your chance of finding Monarch Caterpillars is excellent! Honestly, there is nothing more fun than finding these colorful insects on our milkweed plants and getting to watch them transform into adults!
- Coloring is light green with small yellow dots along the sides.
- This species is small and relatively thin and appears velvety.
- Cabbageworms’ host plants are Brassicas, including cabbage, kale, broccoli, and chard.
In Arizona, this species is often called the Imported Cabbageworm because it isn’t native to North America. It was introduced in shipments of cabbage and other brassica plants and soon became an invasive species.
Cabbageworms are considered agricultural pests and can do severe damage to crops to their host plants. Cabbage, brussels sprouts, broccoli, and cauliflower are all susceptible to damage. For a home gardener, the best way to deal with Cabbageworms is to prevent a large infestation. Plant covers, regular weeding, and varied plantings can all help with preventing this hungry invader!
One reason Cabbageworms are so damaging is that they are voracious eaters! They can easily skeletonize entire plants, eating everything but the toughest stems and midveins. Boring through heads of cabbage and making huge dents in broccoli are no problem for this Very Hungry Caterpillar!
Cabbageworms grow into Cabbage White Butterflies, which are one of the most abundant butterflies in Arizona! If you see a white butterfly in the spring, chances are it’s a Cabbage White!
#3. Woolly Bear
- Pyrrharctia isabella
- Coloring is black with a wide rusty-red band in the middle.
- As its name suggests, the Woolly Bear caterpillar is covered in dense, coarse hairs.
- Transform into Isabella Tiger Moths.
- Woolly Bears are generalist feeders, meaning they will live on and eat nearly any plant!
As a kid, I can remember hearing tons of stories about Woolly Bear caterpillars – and the coolest part about them is that most of the stories are true! One myth you might have heard is that Woolly Bears can predict the type of winter we’ll have. Unfortunately, this one isn’t true. But there’s plenty of other interesting facts about this cute little caterpillar!
The most fascinating thing about Woolly Bears is the way they hibernate.
That’s to say, they don’t hibernate at all! Instead of burrowing or pupating to escape the cold, Woolly Bears allow themselves to freeze solid. They have a unique chemical in their blood that allows them to thaw out and continue in the spring as if nothing happened!
You may have heard that Woolly Bear Caterpillars are venomous, but this isn’t entirely true. Their hairs don’t contain any toxins or irritants, but some people are sensitive to the hairs and may get a slight rash if they touch one. It’s best to observe the species without touching them, just in case.
Woolly Bear Caterpillars and their adult-form, Isabella Tiger Moths, are found in incredibly varied climates, even the Arctic! Because they will eat almost anything, including herbs, tree leaves, and grasses, they can be found pretty much anywhere plants are growing. Look for them in groups near the base of plants.
Just don’t expect them to take over for your meteorologist! 🙂
#4. Viceroy Caterpillar
- Limenitis archippus
- The coloring is mottled brown or green and white to resemble bird droppings.
- Two dark-colored horns on the head and small spines on the body.
- The chrysalis also resembles bird droppings hanging from a tree branch.
- The preferred host plants of Viceroy Caterpillars are willow, poplar, and cottonwood trees.
Viceroy Caterpillars are one of the ugliest caterpillars in Arizona!
This is by design; their lumpy, mottled appearance makes them look like bird droppings, warding off predators!
Interestingly, this isn’t the Viceroy’s only protection against predators. Viceroy Caterpillars eat plants that are rich in salicylic acid, which they store in their bodies. When predators try to eat them, they are rewarded with a strong, bitter flavor and an upset stomach. One taste and they learn to stay away!
Viceroy Caterpillars primarily live in open forests or fields, and they’re found across many different climates. Look for them during spring and summer, which is when the adults typically mate.
Interestingly, Viceroy and Monarch Caterpillars look almost identical.
#5. Variegated Fritillary Caterpillar
- Euptoieta claudia
- Stripes of black, red, and white run the length of the body.
- Black branched spines stick out from each body segment in even rows.
- Variegated Fritillaries will use any plant in the violet or alder family as a host plant. These include common blue violets, yellow alder, and pansies.
Variegated Fritillary Caterpillars share the same name as their adult-form butterflies. They eat ornamental plants like violets, pansies, and passionflower.
Look for these caterpillars in Arizona in meadows, open lots, and fields.
The Variegated Fritillary’s chrysalis is the most beautiful of all the caterpillars in Arizona. This protective shell is where the caterpillar transforms into the adult butterfly. Its pearly white color and shiny gold spikes make it look like an expensive jeweled pendant!
- Manduca sexta – Tobacco Hornworm
- Manduca quinquemaculata – Tomato Hornworm
- These two species have nearly identical coloring: bright green with tiny white lines and black dots.
- There’s a thin, filament-like “horn” on the rear end.
- Hornworms grow up to 3.5 inches in length before metamorphosis.
Tobacco and Tomato Hornworms are so similar that they’re often mistaken for one another! The easiest way to tell them apart is by the color of their horns. Tobacco Hornworms have a red horn, and Tomato Hornworms have a green or black horn. While the adult moths they grow into aren’t quite as similar, they do have the same coloring.
Hornworms are considered one of the most destructive caterpillars in Arizona.
They specialize in eating tobacco, tomato, and other similar plants and regularly cause problems for farms and growers who don’t use pesticides. However, relocating or killing the caterpillars can be enough for many home gardeners to deter any more from eating your plants.
One particularly disgusting enemy of the hornworm is Cotesia congregata. It’s a parasitoid wasp that attacks the caterpillar with venom and then lays its eggs INSIDE the living body. As the caterpillar matures, so do the wasp eggs, slowly feeding on the hornworm until it dies and the wasps hatch. Gross!
#7. Parsley Caterpillar (Black Swallowtail)
- Papilio polyxenes
- The coloring is bright green, with rings of black and yellow dots down the length of the body.
- The head and thorax are slightly larger than the back, and the legs and pro-legs are pronounced and visible even from a distance.
- Parsley plants are the preferred host of this species.
Parsley Caterpillars, sometimes called parsley worms, are the larva of the Black Swallowtail butterfly. They get their name from their preferred host and favorite snack, the parsley plant.
At first glance, it’s easy to mistake a Parsley Caterpillar for a Monarch. But, the coloring is slightly different, and the stripes on the Monarch Caterpillar are a bit thinner. It would also be unusual for a Monarch Caterpillar to eat parsley or other garden herbs since they eat milkweed almost exclusively!
If you’re a gardener, you might consider Parsley Caterpillars a bit of a nuisance since they can decimate a parsley plant quickly. But, if you plant some extra, you’ll be rewarded with sightings of the beautiful Black Swallowtail butterfly in a few weeks!
#8. Flannel Moth Caterpillar (Asp)
- The coloring is off-white to brown and long, thick hair covers the entire body, making this caterpillar resemble a wig.
- Generally, about 1 inch long and 0.5 inches wide.
- Prefers oak, elm, and wild plum trees as hosts.
If you see a very furry caterpillar in Arizona, STAY BACK!
It’s most likely a member of the Flannel Moth family, the most venomous caterpillars in our area. Victims have described the pain from this caterpillar’s sting as similar to a broken bone or a white-hot burning sensation.
Their sting can cause tons of unpleasant symptoms, including swelling, nausea, headache, chest pain, and difficulty breathing. Especially in young children, the symptoms require medical attention, so if you think you’ve been stung, seek help!
Contact with Flannel Moth Caterpillars often happens during gardening or clearing brush. They use many common yard plants as hosts. You should be extra careful if you have oak or elm trees, roses, or ivy in your yard since these are its favorites. These caterpillars are most common in late spring and summer.
It’s always a good idea to wear gloves if you’re working outside, but especially if you have them in your neighborhood!
Adult Flannel Moths are just as furry as their caterpillars, but they aren’t nearly as painful to touch!
#9. Hubbard’s Silk Moth Caterpillar
- Syssphinx hubbardi
- Coloring is green with a violet stripe along the sides, and white dots speckle the body.
- Thin, hair-like spikes cover the body.
- Honey mesquite and catclaw acacia are this species’ favorite host plants.
This caterpillar has an extraordinary talent – it glows in the dark!
While technically this species displays bio-fluorescence, meaning it glows under UV light, it’s one of the only caterpillars in Arizona that can be compared to a glowstick. 🙂
Look for Hubbard’s Silk Moth Caterpillars on desert plants like Wright’s acacia, honey mesquite, and catclaw acacia. They’re most active in the spring and summer.
Interestingly, this species doesn’t attach their chrysalis to a tree when it comes time to transform into a moth. Instead, it creates a shallow hole in the ground, spins its tough outer shell of silk, and settles in for the winter!
Adult Hubbard’s Silk Moths are much more unassuming than their larva, however, they do hide a bright secret under their wings – the top of the lower wings are bright pink!
#10. Large Yellow Underwing
- Noctua pronuba
You’re most likely to find these caterpillars in Arizona in open or shrubby areas, but they are habitat generalists that can adapt to various conditions. For example, they’re happy in urban and suburban areas, fields, agricultural areas, yards, and parks.
The adult moths are mostly nocturnal and are attracted to outdoor lights. You may occasionally spot large groups of them around bright lights.
Large Yellow Underwings might not have the most creative name, but it’s certainly accurate! At rest, their brown forewings usually cover their brightly colored hindwings, but you’ll see a flash of color when they take off! This flash helps to confuse and startle would-be predators.
Large Yellow Underwings have a longer lifespan than many other moth species. In captivity, males live an average of 55 days, and females live about 75 days. Despite their long lifespan, they only have one new generation per year.
#11. Pipevine Swallowtail
- Battus Philenor
Pipevine Swallowtail butterflies constantly move around to find nectar. They particularly like pink and purple flowers! If you want to attract these beautiful visitors, plant nectar-producing flowers like Phlox.
Males actively seek out females when they are ready to mate. Once the female mates, she places her eggs on the undersides of the host plant. After hatching, the caterpillars feed in groups on host plants in the Aristolochia family, like Virginia Snakeroot and Dutchman’s pipe.
Like some other caterpillars in Arizona, the Pipevine Swallowtail is unpalatable to birds and other predators.
#12. Painted Lady
- Vanessa cardui
- The caterpillars’ coloring is variable, ranging from greenish-yellow to charcoal. Most have light-colored spots.
Look for Painted Lady caterpillars in Arizona in open areas that are quiet and undisturbed, like roadsides, pastures, and gardens.
The population of Painted Lady’s can drastically differ from year to year. It’s common for them not to be seen for years in some places, then suddenly show up in significant numbers.
The Painted Lady is the only butterfly that mates year-round! Because of its constant migration pattern, it spends its entire life in suitable areas for its eggs to hatch.
#13. Red Admiral
- Vanessa atalanta
- The caterpillars are pinkish-gray to charcoal with white spots. They have spines along the back that resemble hairs.
Look for this caterpillar in Arizona near the edge of forests in moist habitats.
Red Admiral Butterflies have a unique favorite food – they love fermented fruit! If you’d like to attract them, try placing overripe cut fruit in a sunny spot in your yard.
Red Admirals are migratory butterflies. They fly south toward warmer climates in winter and then move north again in late spring when food is more plentiful.
If you’re looking for a butterfly that’s easy to observe, you’re in luck! Red Admirals are very calm and easy to approach and frequently land on humans!
- RELATED: How to Attract Butterflies: 17 Tips!
#14. Hackberry Emperor
- Caterpillars are light green with two yellow stripes on the back. Two short spines top the head, with two small tails on the rear end.
Hackberry Emperor caterpillars are common in Arizona.
Look for them in moist wooded areas, parks, and suburban yards.
One place you WON’T find Hackberry Emperors BUTTERFLIES is on flowers since they don’t eat flower nectar at all!
Although flowers don’t attract them, these insects are naturally curious and will even land on humans who happen to be near them. One reason for this habit is to ingest sodium from our skin! This may be hard to believe, but Hackberry Emperors find the minerals they need to survive in many unusual places, like soil, rocks, and even pavement!
They also eat sap, dung, carrion, and rotting fruit and drink water from rain puddles. They might be one of the least picky eaters I’ve encountered!
#15. Pearl Crescent
- Phyciodes tharos
- Caterpillars are dark brown with cream stripes and spines all over their bodies.
The Pearl Crescent caterpillar’s preferred host plant is the Aster. Any flowering plants in your yard will attract this beautiful butterfly, but for best results, try to find one native to your area.
Look for Pearl Crescent butterflies in Arizona near moist ground.
They prefer open, sunny habitats, but many locations suit their needs, including forest edges, fields, meadows, and gardens.
When the caterpillars grow into butterflies, they will feed on the nectar of the Asters as well!
#16. Spotted Tussock Moth
- Lophocampa maculata
Spotted Tussock Moths are in the tiger moth family, named for their patterns of alternating dark and light colors. These moths and their caterpillars are what’s known as polymorphic, meaning that they come in many color variations.
You’ll most likely find Spotted Tussock Moth caterpillars in Arizona in deciduous forests. Researchers have found that Spotted Tussock Moths have a regional taste for cuisine, just like people! Caterpillars from certain regions often prefer specific tree species.
After about two months of feeding, the caterpillars pupate. They spin brown silk cocoons attached to leaves where they will overwinter, emerging as adults the following spring.
#17. Mourning Cloak
- Nymphalis Antiopa
- Caterpillars are black with white specks and a row of red spots on the back.
Mourning Cloak caterpillars are most often found near deciduous forests. However, their habitat includes many developed areas like suburban yards, parks, and golf courses.
You might have a hard time finding this caterpillar in Arizona.
Even though it’s fairly widespread, its preference for cold weather and solitary habits make it hard to spot, even for avid butterfly enthusiasts!
Mourning Cloaks are often the first butterflies to become active in the spring! In fact, some adults are even active through winter on warm days when snow is still on the ground.
They’re also one of the longest-lived butterflies, with some individuals living up to ten months!
#18. Western Tent Caterpillar Moth
- Malacosoma californica
In the fall, Western Tent Caterpillar Moths lay about 150 to 250 eggs in oval-shaped masses. They cover the eggs with a gluey cement substance called spumaline, which helps hold in heat and absorbs rainwater to prevent the eggs from drying out. It also protects the eggs from parasitoid wasps.
Even though it only takes three to four weeks for the caterpillars to mature, they must overwinter in this stage before pupating into moths. Their name comes from the silken tent they create to protect themselves from extreme cold during this time.
These caterpillars have a voracious appetite and can quickly defoliate trees in Arizona during a population outbreak. While it may be unsightly, the trees usually recover just fine. Interestingly, these caterpillars have regional tastes, and the specific trees they prefer are highly dependent on their location.
#19. Checkered White
- Pontia Protodice
Checkered White caterpillars are common in Arizona.
One of the most fascinating characteristics of this butterfly is its ability to use UV signals to communicate. These amazing insects can tell the difference between males and females of their species based on the UV radiation they give off! If a female notices that there are a lot of other females, she will migrate to a less dense population in hopes of attracting a mate.
Checkered White Range Map
Checkered White females lay their eggs on the host plants’ fruits and sometimes the stems. The larvae prefer to eat the flower or fruit of the host plant instead of the leaves.
This butterfly prefers open and sunny areas like deserts and plains, and it’s often found in vacant lots, airports, railroads, and dry grassland.
#20. Gulf Fritillary
- Dione vanillae
Gulf Fritillary caterpillars are common in butterfly gardens throughout Arizona.
They prefer sunny open grasslands, woodlands, or parks as their habitat. The best plants to attract these vibrant butterflies are passion vines and Lantana plants.
Gulf Fritillaries have a unique mating ritual where the female and male circle around each other while the male releases pheromones. When the female settles, the male hovers above her, showering her with more pheromones. Then, the male settles beside the female and flaps his wings, covering her antennae to assure her he is the same species.
After the pair mates, the female flies low into vegetation and lays one egg. The female continues laying her eggs on the host plant, usually a passion vine of the species Passiflora lutea or Passiflora incarnata.
#21. White-lined Sphinx
- Hyles lineata
In the spring, the adult females lay hundreds of eggs on host plants. Occasionally, explosive outbreaks of this species occur, and during these times, you might see large groups of caterpillars moving together. They have even been reported to cover entire sections of roadways!
The caterpillars pupate in burrows underground. Pupation takes about two to three weeks, and when they’re close to finished, they wiggle up closer to the surface of the soil before emerging as adult moths.
White-lined Sphinx Moths are sometimes mistaken for hummingbirds. They can rapidly beat their wings to hover at flowers and reach in to sip nectar with their long proboscis. Their favorite flowers include Cardinal Vine, Jimsonweed, Petunia, Phlox, Lilac, Hostas, Honeysuckles, Evening Primroses, and Penstemon.
- Danaus Gilippus
Queen caterpillars are found in open and arid areas in Arizona close to milkweed. Males have a black scale patch that releases pheromones, attracting females to mate with. After mating, the female will stay close to the area where she found the male and lay her eggs nearby.
Queen butterflies lay eggs on milkweed plants.
The fascinating reason for this comes down to self-preservation! Like other caterpillars, these insects consume Cardiac Glycosides from the milkweed plants. These chemicals taste bad to predators and are carried over to their adult stage, protecting them from being eaten.
#23. Two-Tailed Swallowtail
- Papilio Multicaudata
Two-Tailed Swallowtail caterpillars are found in Arizona in areas with open space and plenty of sunlight. Look for them in foothills, canyons, valleys, woodlands, roadsides, parks, cities, and suburb gardens.
Males of this species spend their entire lives finding a female to mate with due to their short lifespan. If it takes a long time to find a mate, males search for nutrients in rotten material, dirt, and sometimes feces, an odd behavior called mud puddling.
Although it’s one of the most recognizable features, the Two-tailed Swallowtail doesn’t need its tails to fly. Instead, they’re often used to escape predators. When a predator attacks the Swallowtail and grabs onto its tail, it breaks off, allowing the butterfly to escape.
Do you need more help identifying caterpillars in Arizona?
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Which of these caterpillars have you seen in Arizona?
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