Moths of the Moraine

When it comes to Lepidoptera, butterflies tend to steal the spotlight. We get it; they fly around during the day, they come in a beautiful array of colours, and they hang around flowers. Moths are a much harder sell. They’re largely nocturnal, so it’s harder to get to know them. Some of them put holes in your clothes or eat the food in your pantry. Despite these apparent disadvantages, moths are an essential part of the ecosystems around us. They’re one of the most astonishingly diverse groups of animals alive today, with over 160,000 species around the world! As we approach our 2024 Moth Night, let's take a minute to appreciate the strange and wonderful world of these nocturnal insects. Here are a few of the more familiar native moths of the Oak Ridges Moraine.

·         The Isabella Tiger Moth (Pyrrharctia Isabella).

Here’s a species that almost all of u are familiar with. The fuzzy orange and black caterpillars of the Isabella tiger Moth are colloquially known as “woolly bears”.  They’re remarkably well adapted for surviving cold conditions, overwintering as caterpillars in subzero temperatures. They’re able to survive being frozen solid over the winter months. This widespread species is distributed from Mexico to Canada and across the US. The caterpillars are generalists, feeding on a wide variety of plants. This allows them to thrive in a variety of habitats.

·         The American Dagger (Acronicta americana)

Another moth species that’s more familiar in its larval form. The American Dagger caterpillar is covered in yellow setae (the insect equivalent of hairs) with a few longer black setae along their bodies. Despite playground rumors, the American Dagger isn’t poisonous. Regardless, handling can cause skin irritation in some people and should be avoided. American Daggers are generalists, using a wide variety of plants as host species for their young. Oaks, poplars, willows, birches, maples- they enjoy them all.  

·         The Virginia Ctenucha (Ctenucha virginica)

Pronounced “ten-OO-shA”. This gorgeous species has black wings, an orange head, and an iridescent blue abdomen. Unlike many other moths, the Virginia Ctenucha is mostly active during the day (diurnal). The hairy caterpillars of this species range in colour from white to yellow. The adults feed on flower nectar and are sometimes mistaken for butterflies. Originally confined to the eastern US and Canada, this species has expanded westward to the prairie provinces and British Columbia.

·         The Eastern Tent Caterpillar (Malacosoma americana)

This species is well known for its elaborate silk nests. This species prefers to lay its eggs on crabapple and cherry trees.  Eastern Tent Caterpillars will build their nests to face the direction of the sun. The warmth of the sun helps the caterpillars to bask. When basking, they clump together tightly to prevent heat loss. The adult moths are nocturnal. This species is a favourite prey item of cuckoos. While the hair-like setae of the Eastern Tent Caterpillar protect it from most predators, cuckoos have evolved to digest these sharp points. The Eastern Tent Caterpillar is sometimes confused with the Fall Webworm (Hyphantria cunea), another species that builds massive silk nests. As their name suggests, the Fall Webworm nests later in the year (summer and fall) versus the Eastern Tent Caterpillar, which nests in spring.

·         The North American Luna Moth (Actias luna)

The astonishingly beautiful luna moth has pastel green wings and a white body. They’re one of the largest moths in Canada, some individuals have wingspans of over 17cm! Bats are prominent predators of the Luna Moth. They’ve evolved a remarkable self-dense strategy, clicking loudly to interfere with the bat’s echolocation and evade capture. If that doesn’t work, they deter predators by regurgitating their stomach contents. In the early 20th century, a parasitic European fly (Compsilura concinnata) was introduced to North America to help control the invasive Spongy Moths (Lymantria dispar). Unfortunately, these flies have had a negative impact on the populations of several moth species including the Luna.