Recently, on a somewhat remote hike in Northern Pennsylvania, I saw what I thought was a piece of trash rolling toward me on a steep incline. I started to ponder the harsh realization that trash often ends up in wild spaces, when the piece of “trash” corrected itself and started crawling back up the trail. I stopped to watch this larva (thinking it must have come out of Alice and Wonderland), and was amazed by just how incredibly large the insect was!

Two photos of cecropia larva on a dirt- and rock-filled trail.

Cecropia larva observed in Northern PA (Photo credit: Christine Danforth, Alliance for the Chesapeake Bay)

Hyalophora cecropia moths emerge from 10 month overwintered cocoons from early April into June. The nocturnal moths live for approximately two weeks with the intent of mating. Female cecropia moths emit mating pheromones that male moths can detect from over a mile away; on average a female moth will lay over 100 eggs. Upon hatching the caterpillars are black in coloration. As the instars progress and increase in size, larvae can reach around 5 inches in size and blueish-green in color. The larvae maintain reddish-orange tubercles with black points, and side rows of blue tubercles. The adult moths lack mouth parts and digestive mechanisms, so the larval stages feed on copious amounts of plant biomass to support the adult stage.

Cecropia moth with bright red legs and a speckled body clinging to a branch.

Hyalophora cecropia moth clinging to a branch (Photo credit: Birds and Blooms).

Cecropia moths are the largest moths in North America and are a member of the Saturniidae Family, the giant silkworm and royal moth family. Acer sp. (maples), Salix sp. (willows), Prunus sp. (cherries), Quercus sp. (oaks), Malus sp. (apples) and other commonly found hardwood species in forests east of the Rocky Mountains act as host plants for the charismatic moth species. The moths have stout hairy bodies and feathery antennae. They maintain brown and reddish-orange coloration. The insect’s average wingspan ranges from 4-7 inches!

Cecropia moth with it's wings spread wide open resting on a person's hand.

Hyalophora cecropia moth (Photo credit: South Caroline Public Radio)

Female bolas spiders, a type of orb-weaver, have the ability to mimic female cecropia moths’ pheromones; this lures in male moths for predation. This unique relationship is known as aggressive chemical mimicry. Another unique relationship that Cecropia moths may be afflicted by concerns the Spongy moth. It is reported that cecropia moths may be in decline in some of their range, as the tachnid fly introduced as a management tool (biocontrol) for the Spongy moth may parasitize larval stages of the cecropia moth. This limits the potential for the final instar to create and enter its pupa.

If you see something blooming, leafing out, ripening, or otherwise changing in your woods, send us photos (forestsforthebay@gmail.com) to include in next month’s Forests for the Bay newsletter for more phenological fun!