Processionary caterpillars in Québec: a false rumor

Pine processionary caterpillars
Credit: CC Flickr (rabiem22)
Pine processionary caterpillars
Processionary caterpillars in Québec: a false rumor

Every year for a few years the arrival of warmer weather has given new life to a false rumor, one that, with the help of social media, is gradually spreading through our society. According to that rumor, the European species Thaumetopoea pityocampa, commonly known as the “pine processionary caterpillar,” is now established in Québec territory. What’s the real story?

What are pine processionaries?

These are caterpillars that are found not in Québec but in all Mediterranean countries. The caterpillars live in colonies and weave silk shelters that allow them to feed on pine needles while remaining protected from bad weather and potential predators. They’re called “processionaries” because they move one behind the other, in single file, when they leave their shelters. Furthermore, in springtime these caterpillars shed their hairs, which are easily borne by the wind and which cause important skin and respiratory allergies in human beings and domestic animals. When the hairs break, they release an urticating substance that gives rise to serious stubborn itching, and which is in turn the source of important irritations and inflammations.

In Québec: caterpillars grouped together, but not the least bit irritating

In Québec we have caterpillars that live in colonies and that in springtime form silk shelters on trees, just like processionaries. Except, in la belle province these insects are called “tent caterpillars” and have very little in common with their European cousins. In fact, the only elements shared by these two groups of caterpillar are their herd mentality and the production of silk shelters. Besides, tent caterpillars never walk nose to tail; instead, they abandon their shelters alone and in different directions. On top of that, to this day their hairs have never provoked allergic reactions either in people or in their four-footed companions.

Let’s be vigilant!

In countries where pine processionary caterpillars are found, some veterinary clinics issue notices over the Internet to inform the owners of domestic animals about the threats these caterpillars represent and what to do to protect their canine or feline companions. So, no matter where we happen to be in the world, those notices quickly end up in our inboxes and on our Facebook pages. All we need to do is compare the insects found outside with those whose pictures are posted on the Web. Nevertheless, vigilance is needed to make sure that the insects we come across in our yards are really not those we hear about…in the virtual world.

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1 Comment(s)
Ronaldroscioli's picture

Interesting about some monarchs migrating up the center part of the United States to the Great Lakes area. Could explain why I have seen adults and full grown larva in the Toronto area in May. Several weeks before I see them in eastern Pennsylvania where I live.

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Anonymous's picture