By Barbara Mackay
The church service was about to begin when some breathless kids pulled me out of my seat to “come see this awesome, pretty, pink-and-yellow, fuzzy baby moth!” on the Sunday school door. It was a rosy maple moth, Dryocampa rubicunda, notable for its dipped-in-sherbet coloring.
The moth’s coloring can vary from pink to purple and from yellow to white. “Our” moth had purplish-pink forewings with a creamy-yellow band across the middle. The hind wings were pale yellow with a touch of pink along the edges. Its woolly body was bright yellow above and raspberry pink below. The same pink spilled onto the legs, much to the surprise and delight of the kids. The head looked like a yellow craft pompom. With wings spread wide, the moth was just over an inch across and just under an inch long.
As I coaxed it from the door handle to my finger, it spread its wings for a brief photo op, but then it seemed to die on the spot. Everyone gasped in shock as I placed it in a nearby bush, where it swung upside down, clinging to a leaf stem. Witness a nifty self-defense strategy: curling up deathlike on one’s side with wings folded in.
Because the moth stayed still for several moments (it is at its most sluggish on cool mornings), we were able to observe its antennae. Even without a hand lens, we could see that they were bright pink and feathery. Female antennae have a simple feather-like arrangement, while the male has a more complex structure. Our moth appeared to be a female. That supposition signified a need for increased observation of the nearby maples during the next few weeks: Dryocampa rubicunda adults may be darling, but their larvae can be destructive.
But before there are larvae, there are eggs. And before there are eggs, there is mating, which usually takes place in the evening. If successful, a female lays up to 200 eggs in groups of 10 to 30 on the undersides of the leaves of a host tree the next night. Trees of choice are silver, red, and sugar maples, but they might also select oak trees in some areas.
Two weeks later, the tiny yellow eggs hatch. At first, the caterpillars – called green-striped mapleworms – stay together and feed voraciously. Starting at the leaf margin where they were born, the caterpillars systematically eat their way toward the midvein of a leaf, then move on to the next. The adult moths don’t feed and few trees are completely defoliated – a tree would likely consider the insect a nuisance, but not a threat.
The caterpillars are pale yellow-green, with green stripes running the length of their body. Two rows of short black spikes grow out of each segment. The second segment has two long black horns. Two long black filaments protrude from the back of the head. There is a small pink marking near the rear of an immature larva. The caterpillar goes through three instars (molting stages) and as it grows these pink markings change to deep-red. The head changes from black to brown to red. The final molt results in a thick-skinned caterpillar that is almost two inches long and is a darker, greenish brown than was its pale, younger self.
Month-old caterpillars move to ground. They burrow just below the soil’s surface underneath the host tree, creating chambers in which to pupate and spend the winter. The pupae are dark brown, with the segments of the caterpillar stage still visible. Protected by insulating snowfalls, the pupae survive cold winter winds and temperatures. The adults emerge the following spring. In the Northeast, they fly from May to August, reproducing only once.
Like many moths, rosy maples are attracted to lights at night. You can increase your chance of seeing this “awesome, pretty, pink-and-yellow, fuzzy baby moth” if you have maple trees and a porch light.
Barbara Mackay is a teacher and naturalist who lives in northern Vermont. The illustration for this column was drawn by Adelaide Tyrol. The Outside Story is assigned and edited by Northern Woodlands magazine, and sponsored by the Wellborn Ecology Fund of the New Hampshire Charitable Foundation: firstname.lastname@example.org.