Virginia Ctenucha

Welcome to Insect Appreciation Days, celebrated from June 8 – 13^th annually, thanks to the Entomological Society of Canada. And what better insect to profile than PEI’s most commonly-reported moth, the Virginia Ctenucha (Ctenucha virginica)!

First, what’s up with that name? Ctenucha (ten-OOO-sha) comes from a Greek word for ‘comb’, and refers to the feathery, comb-like antennae of the male moths. (The individual shown here is a female, with more wiry, less feathery antennae). Virginia is just a common epithet for species native to eastern North America; for example, more than a dozen PEI plants – from Ironwood to Wild Strawberry – share the species name ‘virginiana’.

Virginia Ctenucha is common, distinctive, and active during the day as well as at night, which explains why it is so often seen and recorded. With its unmistakeable combination of bright orange head, shiny blue body, and grey-black wings, this moth always reminds me of someone wearing a floor-length, flowing cape.

This native insect overwinters as a caterpillar, pupating in May and emerging in June as the adult you see here. After mating, the female lays her eggs on grasses and sedges that will feed the caterpillars once they hatch. Those caterpillars mature through several stages (instars) and pupate to emerge as a second flight of adults later in the summer, starting the cycle again. Caterpillars from this second generation burrow under rocks or leaf little in fall to overwinter.

Being a moth is not easy, and Virginia Ctenucha has three strategies to protect itself from predators. First, that metallic blue body mimics certain types of stinging wasps; the Virginia Ctenucha is one of the Wasp Moths, a whole group that uses mimicry to deter predators. Second, this moth is able to make high-frequency sounds that confound bats’ echolocation system, essentially jamming that predator’s sonar. Finally, Virginia Ctenuchas are able to concentrate toxic chemicals called pyrrolizidine alkaloids (PAs) from some of the plants they feed on (regular followers of this page may remember that PAs are found in species including Borage, Coltsfoot, Comfrey, and Tansy Ragwort).

Adult Virginia Ctenucha moths feed on nectar, providing pollination services as they go. They are lovely and helpful parts of PEI Untamed!