Wednesday, June 11, 2014

Promethea Silkmoth (Callosamia promethea)

The Promethea Moth is common in most of its range, which includes south-central Hastings County in Ontario. Yet despite their large size and striking appearance these moths are seldom encountered due to their nocturnal habits, and when resting they hang out the trees where their patterning makes them difficult to spot. (Another seldom seen Saturniid is the Io Moth – live moths are few and far between but it's not uncommon to find the remnants of the wings of individuals that have been bagged by bats.)

This pair stood out like a sore thumb, but then again, as a rule one doesn't expect to see a pair of these moths in the grass at the edge of a parking lot ensuring their genes are passed on to the next generation. In the case of Callosamia promethea this happens from late afternoon until evening, and the eggs are laid at night.

The larvae eat the leaves of a variety of trees – maple, cherry, birch – this caterpillar was found on White Ash. In our area they pupate in early autumn, and the adults emerge in late May or early June to begin the cycle anew. Adult Promethea Moths don't have functional mouthparts and live only a few days, surviving on the energy stored in their tissues from their time as a caterpillar.

Promethea Moths are sexually dimorphic, with the male being smaller and much darker than the female, and lacking the chevron-shaped spots on the upper surfaces of its wings.

The wingspan varies from 75 mm to 95 mm, but the female seemed larger than this.

As if finding a mating pair of these large moths wasn't surprise enough, not fifteen meters away was another female taking shelter in an alcove. She looked like she had only recently emerged and was moved to the safety of a nearby park, as there was too much traffic, both pedestrian and vehicular, in the area.

To learn more about this beautiful insect visit Butterflies and Moths of North America.