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“Treasures of the Ottawa Valley” Nature Talk, March 16 2023

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Science & NatureWhat is That?What Is That ... Fuzzy Caterpillar?

What Is That … Fuzzy Caterpillar?


This time of year, the sights at the cottage are less varied and the sounds more peaceful.  Gone are the jet skis and the high-powered bass boats.  We are left with a few intrepid resident and migratory birds, some hardy mammals, and a juvenile loon diligently learning to fly.  Sightings along the road are fewer and farther between.  The whitetail deer are still with us but they have turned brown like the forest.  Our focus is down, down, down to the roadside and the surface of the road where some caterpillars are rushing to the south side while others of the same species are heading for the north shoulder.

Carolyn prefers to scrutinize the fuzzy caterpillars which somehow seem friendlier, less worm-like, than their less bristly cousins.  Perhaps they remind us of childhood.  We were quite young when we learned to identify the woolly bear  caterpillar but quite old before we began to associate it with the Isabella tiger moth, its adult form.  Stories abound about this caterpillar’s role in foretelling the severity of the winter, some saying thickness of the ‘coat’ portends a heavy winter, others saying it is the breadth of the orange or the black bands that are the predictors.  Our dry, factual sources tell us such stories are myths.  The woolly bear over winters in leaf litter, the hardy ones reappearing in spring to pupate into the Isabella tiger moth.

The other fuzzy bear in the neighbourhood is the yellow bear caterpillar whose colouration varies considerably from individual to individual from beige to yellow to dark red-brown.  It may be spotted on low-growing woody plants and trees.  The yellow bear pupates into a lovely white moth, known as the Virginia tiger moth.

A cousin of the Isabella and Virginia tiger moth caterpillars is the great tiger moth caterpillar, its hairs or bristles presenting as two distinct lengths.  The bristles of the under layer which show as an orangey brown colour are interspersed with longer black bristles, termed lashes, which form a protective barrier.  We see the great tiger moth caterpillar early in June and the adult moth in mid-August.  Our sources tell us the great tiger moth caterpillar over winters, completing its development in the spring, before emerging as an adult.


We have managed to photograph three different species of tussock moth caterpillar at the cottage.  These pretty caterpillars get their name from the clusters of bristles which form their protective coats.  Caution is recommended as some sensitive people may be allergic to the toxins of these bristles.  Carolyn’s favourite is the hickory tussock moth caterpillar with its base of white and its prominent black lashes.  These caterpillars feed on a wide variety of woody forest plants.

You may be able to see the cousinly similarities of the hickory tussock moth caterpillar with the banded tussock moth caterpillars which also feed on a wide variety of woody shrubs and trees. The banded tussock moth caterpillar varies in colour from yellow-brown to grey-black with conspicuous white and black lashes at either or both ends.

Our third tussock caterpillar is the streaked tussock moth caterpillar whose picture Bruce took shortly after one of our many rain storms this summer.  It is clear to see that this dirty brown caterpillar was moving from left to right.  The streaked tussock moth caterpillar also feeds on the woody plants of the forest.

Some people may be concerned about these moth caterpillars munching away our forests but bear in mind they are an important food source for many of our lovely birds, in addition to being important prey items for bats, amphibians, and other invertebrates.  In addition, many of the adult forms are significant pollinators.

Wagner’s Caterpillars of Eastern North America provided the main scientific information used for this article, supplemented by Beadle and Leckie’s Peterson Field Guide to Moths of Northeastern North America.  Of course, the observations are our own, as are the photographs.




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