Moth Monday: Oak Processionary

Quite a notorious moth, the moth for today! The Oak Processionary (Thaumetopoea processionea) makes headlines when spotted. The main reason for that is the hairiness of the caterpillars. Yes, even certain moths go through a hairy phase when hitting puberty 😉 Caterpillars molt a number of times before pupating. During this period, more and more hairs (setae) grow. In the later stages, these hairs readily break and come into the environment. Normally, hairs aren’t a problem, but these particular hairs contain a toxic protein that causes skin and respiratory allergies. A few hairs wouldn’t be a real issue, but these caterpillars tend to stick together in large groups. When they move in large rows or processions, the hairs fall off their bodies and are spread out by wind and water. Humans who come in contact with these hairs might experience skin rashes, conjunctivitis, asthma or severe allergic reactions, although the caterpillars never caused any deaths. As a moth, the animals are relatively harmless. The number of caterpillars fluctuate over the years. Some years there are serious outbreaks of these caterpillars. Several countries have methods in place to counteract such outbreaks and warnings are posted when entering an area where these animals were seen.


I have seen small numbers of these caterpillars (no pictures), but at that time I never wondered what the adult would look like. Then, during one of my lunch breaks in 2015, I spotted this moth. It wasn’t until this year that I rediscovered this picture. For this blog series, I tried to determined the moth and was surprised to find that it was a male Oak processionary moth. Fortunately, I never experienced any side effects 🙂


Another fun fact: The name for the oak processionary is the same across languages. No strange names from the Brits this time!



3 thoughts on “Moth Monday: Oak Processionary

  1. Very interesting moth/caterpillar. Not sure if I’m glad we don’t have then in the U.S. or a little disappointed.

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