A reader recently wrote to us inquiring about the possible health threat that tent caterpillars (sometimes called “tent worms” because, well, caterpillars look like worms) may present to children. The reader is worried that a child’s habit of playing with tent caterpillars (or perhaps just a single tent caterpillar) is dangerous. In this article, we’ll cover the potential dangerous of tent caterpillars, first addressing the topic with regard to humans, and then with regard to animals and plants.

Given that playing with caterpillars is a great amusement (er, for children, that is), we are happy to report that playing with tent caterpillars is not very dangerous, as they are generally not poisonous (at least not to humans). However, tent worms do have small hairs on their bodies that can be irritating to people and animals. If a child is experiencing irritation, most likely on the skin, this may be due to him or her playing with tent caterpillars.

Tent caterpillars can also cause problems beyond mere skin irritation in animals. For example, a large number of mares in Kentucky were being afflicted by a phenomenon known as Mare Reproductive Loss Syndrome, which causes pregnancy failures in female horses, and this was attributed to an outbreak of tent caterpillars.

As we have seen, tent caterpillars aren’t very harmful to humans, and only in rare instances do they negatively affect animals. To us sentient beings, there isn’t much to fear when it comes to interacting with tent caterpillars, but this is emphatically not the case with trees and plants, which can be severely compromised by tent caterpillars. A tent caterpillar infestation can wreck havoc on tress, gardens, and crops, making them a huge pest for landscapers, gardeners, and farmers. Tent caterpillars have enormous appetites and they eat vegetation until there is basically nothing left. Despite the damage they can cause, it is worth noting that trees can be surprisingly resilient in the face of an infestation. Tent caterpillars cause trees to defoliate, which is a problem, but an established tree can withstand 25 percent defoliation without succumbing to any problems. Newer and smaller trees, on the other hand, can be damaged by lesser infestations, so it is important to address a tent caterpillar infestation soon after discovering it if you are dealing with trees that aren’t fully developed.

To conclude, caterpillars do not present a significant risk to humans per se, but they can affect things that people care about, namely, their animals and their plants. Thus, in an indirect way, tent caterpillars can harm humans, but not the way our reader was concerned about.

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