Hickory tussock moth caterpillar
Home Health And Wellbeing Circulating Health Warning: Beware of Little White and Black Caterpillars

Circulating Health Warning: Beware of Little White and Black Caterpillars

by Brett M. Christensen


Message circulating via social media and email warns people to watch out for little white and black caterpillars because numerous kids have experienced reactions and rashes after touching them. 

Brief Analysis

Hickory tussock moth caterpillars, which have a distinctive white and black colouring, can excrete a venomous substance on contact that can cause a painful rash and, in rarer cases, more severe reactions. However, they are not new nor are there any indications that the caterpillars are currently causing more health problems than they have in the past. It should also be noted that many other kinds of caterpillars that live in various parts of the world can also cause rashes and skin reactions when touched. 



FYI!!! Little white and black caterpillars are all over and are POISONOUS. They are apparently new to the area…. Doctors say there have been numerous kids having reactions to them. The rash spreads fast. The caterpillars have long white hairs that embed in skin and send poison throughout the body.… DO NOT TOUCH!! They look cute and fuzzy, BUT THEY ARE NOT!! Please re-post to anyone with little kids

Black and White Caterillars


Detailed Analysis

This message, which circulates via Facebook and other social media sites as well as email, warns recipients to watch out for little white and black caterpillars. According to the message, if touched, hairs from the caterpillars can embed in your skin and send poison throughout your body causing a fast-spreading rash. The message suggests that the caterpillars are “new to the area”. It also claims doctors have been reporting numerous cases in which children have experienced reactions after touching the wee beasties.

The core claims in the message are factual. Touching the creatures can often cause skin irritation and, sometimes, more severe reactions. Nevertheless, the warning is somewhat overblown and its general vagueness lessens its credibility and value.
The message does not actually name the type of caterpillar it is warning people about. However, the description suggests that the message is referring to the hickory tussock moth caterpillar, which is indeed white, black and fuzzy. If touched, this caterpillar can excrete venom via sharp black hairs located near the creature’s front and rear. The venom can cause a rash similar to that caused by poison ivy. Information about this caterpillar published on AskTheExterminator.com explains:

Contact with the venom does not generally cause too much of a problem. A nettle or poison ivy-type rash often occurs, which can range from mild with slight reddening of the skin, to burning, swelling and pain, none of which should keep you away from your gardening duties for too long. Hypersensitive individuals may, of course, experience more severe symptoms that could include swelling and nausea.

The warning message claims that the caterpillars are “new to the area”. However, it does not state which region, or even which country, the “area” pertains to. The hickory tussock moth caterpillar can be found in southern regions of Canada and in the south-western and north-eastern United States. I could find no reports that suggest that contact with caterpillars are currently causing significantly more doctor visits or hospitalizations than they have in the past.

Another problem with the warning is that it focuses on only one type among many “hairy” caterpillars that can cause rashes and other reactions when touched. There are in fact dozens of such stinging hair caterpillar species that live in various locations around the world. A fact sheet published on the Ohio State University website notes:

Caterpillars or larvae of certain moths possess stinging hairs. These sharp hairs or spines are either hollow, connected to poison glands (venom flows on contact), or similar to glass fibers (hairs break off in skin easily) sometimes causing pain like a needle prick. Depending on the individual, reaction to the sting ranges from mild, with local reddening, swelling, burning and itching to severe pain. Hypersensitive persons may experience severe swelling, nausea and generalized systemic reactions, occasionally requiring hospital treatment. In severe cases, entrance of hairs into the eye can cause blindness.

In 2013, another message began circulating that described an incident in which a child touched a white caterpillar and experienced swelling and a rash. The message notes:

Just to give all you parents a heads up…..Evan pet a white caterpillar this weekend and within 10 minutes his finger swelled up and this happened. These caterpillars are poisonous…alive AND dead so please caution your kids and tell them DONT touch caterpillars.

The message includes an image depicting how the child was affected. The message does not give enough details to identify the species of caterpillar that cause the child’s reaction. However, it may well have been a hickory tussock moth caterpillar

Many youngsters – my much younger self included – have found out the hard way that playing with cute hairy caterpillars is not a wise move. In Australia, such caterpillars are often colloquially referred to as “itchy grubs” for obvious reasons. As noted above, reactions to hairy caterpillars can sometimes be quite serious. But, most of the time, some basic rash first aid and a good cuddle from mum are enough to set things right.


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Brett Christensen