Hyalophora cecropia
North America's largest native moth, with a wingspan of up to 18 cm. A Saturniidae giant silk moth whose larvae feed on a variety of deciduous trees including maple, birch, cherry, and sassafras. Adults lack functional mouthparts and live only about two weeks.
Seasonal Activity
Diet
Foliage of maple, birch, cherry, apple, sassafras, and other deciduous trees and shrubs (larva); adults do not feed
Lifecycle
One generation per year. Eggs are laid in clusters on host leaves. Larvae pass through five instars: first instar is black, later instars become yellow-green then large and bluish-green with blue, yellow, and orange tubercles. Mature caterpillars reach 10-11 cm in length. In autumn, the caterpillar spins a large brown silk cocoon attached lengthwise to a tree branch, where it overwinters as a pupa. Adults emerge in early summer. Males detect female pheromones from over 1.5 km away; mating occurs in early morning. Adults live approximately two weeks.
Ecology
Native Habitats
Details
Description
The Cecropia Moth (Hyalophora cecropia) is North America's largest native moth, with females reaching a wingspan of 13-18 cm. It is a member of the Saturniidae, the giant silk moth family. The wings are rich brown with red near the base of the forewing and distinctive crescent-shaped spots of red with white centres on all four wings — larger on the hindwings. The body is hairy and banded with alternating red and white on the abdomen.
This species holds scientific significance: the insect juvenile hormone was first described from cecropia silkworms by Carroll Williams in 1956, and the antimicrobial protein cecropin was named after this moth. It is ranked Secure (G5) globally and ranges across eastern North America into the majority of Canadian provinces.
Lifecycle
Cecropia moths produce one generation per year. Females emit pheromones at night to attract males, which can detect these chemical signals from over 1.5 km away using their large, plumose antennae. After mating, a female lays up to 100 mottled reddish-brown eggs on host leaves.
Larvae progress through five instars over approximately five weeks. First-instar caterpillars are black. By the second instar, they become yellow-green, and in the third through fifth instars they grow very large and bluish-green, with prominent tubercles coloured blue, yellow, or orange depending on body location. Mature caterpillars reach 10-11 cm in length by autumn.
The caterpillar spins a large, brown, spindle-shaped silk cocoon attached lengthwise along a tree branch. The pupa overwinters within this cocoon. Adults emerge in the first weeks of warm weather in early summer (May-July). Like all Saturniidae, adult cecropia moths lack functional mouthparts and a digestive system — they survive solely on fat reserves and live only about two weeks, their brief adult life devoted entirely to reproduction.
Ecology
Larvae are generalist feeders on a wide variety of deciduous trees and shrubs. Common hosts include maple (Acer), birch (Betula), wild cherry (Prunus), apple (Malus), and sassafras (Sassafras albidum). The species does not cause significant defoliation of host trees.
Adult moths fall prey to birds, bats, and squirrels. The pupae are particularly vulnerable to woodpeckers, squirrels, and parasitoid wasps and flies. The introduced tachinid fly Compsilura concinnata, originally released to control Spongy Moth, is a significant threat to native cecropia populations. Light pollution and pruning of host trees also negatively impact the species.
Host Plants
Larvae feed on a broad range of deciduous trees and shrubs. Key hosts include:
- Maple (Acer species)
- Birch (Betula species)
- Wild Cherry (Prunus serotina)
- Apple (Malus species)
- Sassafras (Sassafras albidum)
- Willow (Salix species)
Habitat
Cecropia moths inhabit deciduous forests, woodland edges, and suburban areas with mature host trees throughout eastern North America. In Ontario, they occur across the Carolinian Forest zone and extend into the Great Lakes-St. Lawrence forest region. The species readily uses urban and suburban trees, and cocoons are often found on ornamental plantings.