Are Wooly Worms Poisonous (or Venomous)?

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When it comes to toxic or poisonous caterpillars, you may have heard that wooly worms are the worst offenders to be worried about. But are wooly worms poisonous? Or is this just another widely believed myth?

Woolly worms are also known as the Isabella tiger moth, woolly bear caterpillar, or woolly bears and there are many misconceptions about exactly how dangerous they are. Read below to discover everything you need to know about wooly worms and whether they pose a potential poisonous threat to you and your household.

Is a Wooly Worm Poisonous or Venomous?

Although woolly worms do not pose the same kind of venomous or poisonous in the sense that they will attack, bite or sting you – picking up these caterpillars will expose your skin to chemicals on their furry body which can irritate your skin and cause dermatitis.

Many people will be able to pick up these creatures without suffering from any stings, but some people will find that their skins are susceptible to an allergic reaction from the chemicals which are on the caterpillars hairs.

When you pick up woolly worms, they will likely roll up into a ball as a defense mechanism with their stinging hair up in spikes. They will not bite or sting despite what you may have heard.

If you pick them up in this state you will find that your skin may end up with a rash, red swollen skin, and a stinging sensation which causes you a considerable amount of discomfort. In extreme cases of allergic sensitivity, the area may begin to feel numb and you may begin to feel nauseous. Whether you react at all and to what severity will depend upon the sensitivity of your skin, your immune system, and whether you are naturally allergic to any of the chemicals on the caterpillar spikes.

If you are experiencing irritation after coming into contact with fuzzy caterpillars, you need to take steps to remove the remainder of the spikes and hair from your skin in order to stop the irritation. Rinsing and washing your skin gently with warm water may help to do this, you can also apply an antihistamine or hydrocortisone cream or other soothing over-the-counter creams. You can also use some adhesive tape to stick down onto your skin and hopefully remove the hairs when you remove the tape.

If symptoms worsen over time you should contact a doctor as you may be experiencing a more severe allergic reaction that needs medical attention.

Do Wooly Worms Bite?

Despite what you may have heard, wooly worms are not in the habit of biting people. As with most caterpillars, coming into contact with a woolly worm is actually usually a harmless encounter, unless your skin is susceptible to irritation caused by the chemicals on a woolly bear caterpillars hair.

If you have been bitten by a caterpillar, chances are it wasn’t a woolly worm. Some of the caterpillar species which do bite include saddleback caterpillars, flannel moths, and buck moth caterpillars. if you can see a bite mark on your arm after coming into contact with a caterpillar you should do an image check to double-check exactly what species you have come into contact with.

Do Wooly Worms Sting?

Coming into contact with woolly bear caterpillars may result in a stinging sensation, but it won’t be because they have actively tried to sting you. Instead, they may have assumed their defense mechanism pose with their spikes pointing outwards. If you have then come into contact with this furry creature’s stinging hairs, you may find that you have a sensitivity that results in a red stinging rash, bumps, and soreness. So, although the effect may feel the same, woolly bears will not sting you in the same way spiders or other insects might.

Some types of caterpillars will sting you, and these include flannel moths, saddleback moths, and gypsy moth caterpillars.

Are Wooly Worm Hairs Poisonous to the Touch?

Woolly bear caterpillars can irritate the skin of some people if their stinging hair spikes are left on the skin after an encounter. Although usually, this will result in an irritating rash in people who have sensitive skin or may be allergic, in some rare cases you may find that the area begins to feel numb and you may start to feel symptoms of nausea. But in the majority of cases, people will find that they can come into contact with these creatures with little to no irritation or pain felt at all.

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Can You Be Allergic to Wooly Bear Caterpillars?

It is possible to be allergic to the chemicals which are on the small stinging hairs that wooly bear caterpillars will expose to your skin when they roll up in a defensive position. The extent of the allergy and the reaction will vary from person to person, with some people experiencing minimal reactions and others experiencing more pronounced rashes, bumps, and numbness.

If you are worried about the symptoms you are experiencing after coming into contact with a woolly bear or any other caterpillar you should contact a medical professional as soon as possible. If you noticed the color and appearance of the caterpillars you came into contact with, do a google search so you can give the doctor a good idea of the skin irritation you are dealing with.


Woolly bears are by no means the most venomous or poisonous of caterpillars and will generally pose no health risks. In contrast to some other species of caterpillars, the banded woolly bear (aka the wooly worm) will not actively sting or bite you.

However, if your skin comes into contact with woolly bears, the creatures may roll up into a ball to defend themselves against what they perceive as predators. When they do this, their hair will form spikes which can cause irritation if you have sensitive skin or allergies. The extent to which you experience stinging, pain, or discomfort will depend upon your individual level of skin sensitivity and your immune system.