Summary: Woolly bear caterpillars, also called Isabella tiger moth caterpillars, are some of the fuzziest pests ever – but are they secretly dangerous? This blog details the simple lives of these soft creatures, including their appearance, transformation, habitats, and food sources. Pointe Pest Control provides reliable pest control services for Missouri and Illinois homeowners.

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The critter that would win the award for “Most Puppet-Like Pest” is definitely the woolly bear caterpillar. It may look like a fuzzy stuffed animal, but it’s actually an active moth caterpillar that spends its time eating plants and searching for cozy shelter.

Found throughout the U.S., the woolly bear caterpillar looks like a harmless creature. But is it a hidden danger, or does it give us total warm fuzzies? Let’s find out by diving into the cozy activities and slow lifestyle of the fuzziest caterpillar around!

The Woolly Bear Basics

Since the woolly bear caterpillar is common in both Illinois and Missouri, you might already be familiar with this insect. It gets around by walking or creating a bit of silk to catch the wind and “balloon” the caterpillar to a new location. There are quite a few names for this caterpillar, including woolly bears, woolly worms, woolly bear caterpillars, and Isabella tiger moth caterpillars.

Woolly bear caterpillars are:

About 2 inches long
Covered in stiff hairs
Multi-colored, with black ends and a reddish-brown band in the middle

There’s an old wives’ tale that the size of this caterpillar’s bands predicts the incoming weather. Similar to the myth that cricket chirps determine the temperature (spoiler alert), this isn’t true. The color bands are impacted by the weather — just not in the way you think! Caterpillars that are exposed to lots of moisture have more black, while older caterpillars have more red.

The Flight Of Adult Isabella Tiger Moths

Before we move further into the lives of woolly bear caterpillars, it’s worth discussing the habits of their adult selves. After all, the patterns of the caterpillars aren’t too far off from the adult moths they become!

Isabella tiger moths have yellow-brown wings with dark spots. They rest with their wings pointed up, making the pattern more obvious. You’re most likely to see these moths from April through September. They stay near plants and foliage for the sake of their offspring, as they lay eggs directly on plants to give the larvae a food source. These eggs hatch less than 2 weeks later.

There are 2 broods of Isabella tiger moths — and woolly bear caterpillars — each year. One hatches in May and the other in August. The August brood overwinters as caterpillars, then becomes adults in the spring and lays eggs that hatch in May. The May brood becomes adults in the summer, then lays eggs that hatch in August.

Their Living Situation

We see more woolly bear caterpillars in the fall, but they’re technically active in other seasons as well. They molt about 5 times throughout their lives, shedding their outgrown skin each time. The goal of the woolly bear caterpillar is to grow and thicken in order to complete their metamorphosis, which is completed in a cocoon made of the caterpillar’s hair!

These caterpillars can overwinter because their strong hairs and glycerol (natural antifreeze) prevent them from being frozen. They typically overwinter under leaf litter and natural debris for additional warmth. You may see more of these caterpillars in the fall during their search. While other insects have already died off, this caterpillar is seen crossing sidewalks and streets in pursuit of shelter.

**Plants Are Food And Friends**

While woolly bear caterpillars aren’t the most destructive garden pests, they do eat enough for us to notice. They are herbivores and therefore only eat plants and plant materials. Isabella tiger moths hardly eat anything since their younger stages do all of the eating for them.

The woolly bear caterpillar’s favorite foods are:

Grasses
Dandelions
Elm trees
Clovers
Sunflowers
Maple trees
Ornamental plants
Weeds
Flowers

As we mentioned earlier, you don’t have to worry about woolly bear caterpillars devouring your entire garden. They’re not usually found in large groups, and a small number of caterpillars isn’t the worst garden presence ever. They also help control weeds, which is a major plus.

However, woolly bear caterpillars aren’t picky eaters. They’ll eat anything from dandelions to ornamentals to clovers. If you allow caterpillars to feed on your garden for a while, your plants will eventually pay the price.

A Dangerous Bear?

The woolly bear caterpillar is one of the more tempting pests to actually touch, thanks to their fuzzy exteriors. You don’t have to worry about being bitten or stung, but there is technically a risk to touching this caterpillar.

Some people get a rash when they touch woolly bear caterpillars. This reaction is entirely dependent on the person and their allergens, as well as the genetic makeup of the caterpillar. The rash isn’t permanent or lethal, so these insects aren’t worth fearing. If you do get a rash after handling one, wash it with soap and water before applying hydrocortisone cream.

The woolly bear caterpillar only really achieves “pest” status when they’re eating our gardens. They’re not the worst, but they’re still annoying in large numbers. The easiest way to control them is to pluck them off your plants by hand when you spot them. Make sure to wear thick work gloves when handling any caterpillars!

Protect The Plants With Pointe!

Woolly bear caterpillars aren’t a major pest that need to be controlled, but there are plenty of other plant pests to frustrate everyone. The licensed technicians of Pointe Pest Control provide customized treatment plans for every customer. We deliver long-term solutions — rather than temporary fixes — for even the toughest of pest problems. Our services operate on a year-round basis in order to provide you with constant protection from destructive pests.

Recurring pest services are the most efficient way to keep a pest-free home. Between the targeted treatments and our expert advice, you won’t have to face a pest problem alone when you choose Pointe. Contact us today for a free quote on our dependable services!

Citations

Are woolly bear caterpillars good for the garden?. (2025, January 7). Anleolife. Retrieved February 10, 2025, from https://www.anleolifeshop.com/blogs/garden-center/are-woolly-bear-caterpillars-good-for-the-garden?srsltid=AfmBOorZTUMCz5fsxJKKAlRkwvH01Av64KEyQglr4uaVkmI2KMXbmGNE

Beth. (2021, October 14). Wooly bear caterpillars. Nature, Garden, Life. Available at https://naturegardenlife.com/2021/10/14/wooly-bear-caterpillars/ (Accessed on February 7, 2025).

Hoff, M. (2024, Septemeber-October). Banded woolly bear (Pyrrharctia Isabella). Minnesota Conservation Volunteer. Available at https://www.dnr.state.mn.us/mcvmagazine/issues/2024/sep-oct/profile.html (Accessed on February 7, 2025).

Isabella tiger moth. (n.d.). University of Illinois Urbana-Campaign: Illinois Pollinators. Retrieved February 7, 2025, from https://illinoispollinators.org/isabella-tiger-moth/

Isabella tiger moth (woolly bear; wooly worm). (n.d.). Missouri Department of Conservation. Retrieved February 7, 2025, from https://mdc.mo.gov/discover-nature/field-guide/isabella-tiger-moth-woolly-bear-woolly-worm

Woollybear caterpillar. (2016, September 13). Iowa State University: Extension and Outreach. Retrieved February 7, 2025, from https://yardandgarden.extension.iastate.edu/encyclopedia/woollybear-caterpillar