The Rosy Maple Moth ( Dryocampa rubicunda ) is a North American moth belonging to the Saturniidae family, also known as the great silk moths. These moths are known for their striking and vibrant appearance, with both the adult moths and their caterpillars boasting unique colorations.
Physical Description
Rosy maple moths exhibit sexual dimorphism, with males and females having distinct appearances. Males have a wingspan of 32-44 mm (1.25 to 1.75 inches), while females are slightly larger, with a wingspan of 40-50 mm (1.5 to 2 inches).
The entire body, including the head, thorax, and abdomen, is covered in a dense coat of orange-yellow fur. The legs and antennae are reddish-to-pink, and the eyes are proportionately large and black. The wings, both primary and secondary, are soft pink with a dull white to yellowish-cream blotch running through the middle. However, coloration can vary significantly, ranging from bright yellow to cream to white. The side, legs, and antennae are usually rose pink.
Males have bushier, bipectinate (comb-like on both sides) antennae compared to the simple antennae of females. This adaptation allows males to better sense the pheromones released by females during mating. Males also have narrower and less rounded wings than females.
Distribution and Habitat
Rosy maple moths are found across eastern and northern United States and adjacent regions of Canada. Their range extends from Nova Scotia west through Quebec to Ontario and Minnesota, and south throughout Florida, the Gulf Coast, Dade County, and the eastern parts of Texas.
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They typically inhabit temperate deciduous forests, nearby suburban areas, and urban landscapes. Their common name derives from their preference for maple trees, including red maples (Acer rubrum), sugar maples (Acer saccharum), silver maples (Acer saccharinum), and box elder maples (Acer negundo).
Life Cycle
The rosy maple moth undergoes a complete metamorphosis, with four distinct life stages: egg, larva (caterpillar), pupa, and adult (imago).
Egg
Females lay pale yellow, ovular eggs in clusters of 10 to 40 on the undersides of maple leaves, and occasionally on oak leaves. Egg laying typically occurs in the warmer months, with a peak in July, although precise timing depends on the region. In northern regions, one brood is laid between May and August. Further south, two broods are laid between April and September. The eggs have a diameter of about 1.4 mm and hatch after about two weeks (10 to 14 days).
Larva (Caterpillar)
The emerging caterpillars, also known as greenstriped mapleworms, mainly feed on the leaves of their host maple trees. The larvae go through five instars (developmental stages) prior to adulthood, during which their coloration and eating behavior changes.
In early instars, the larvae have relatively large black heads and pale yellow-green bodies with faint green stripes. They have two large dark-green to black tubercles on the second thoracic segment and three rows of smaller spines, or setae, on each side of their body. The larvae undergo their first molt around 6-11 days after hatching, their second molt approximately 12 days after hatching, and their third molt around 19 days post hatching.
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In later instars, the black head becomes smaller relative to the diameter of the body and the longitudinal stripes darken and become reddish. In the final instar, the head becomes yellow, and eventually bright red. The mature larvae are light green with black lateral lines, red heads, and two filaments behind the head, and reach lengths of about 55 mm.
Caterpillars live and feed in groups until the fourth instar when they become solitary. Their host plants/trees usually include oak and maple.
Pupa
After about a month, full-grown caterpillars crawl to the bottom of the host tree and pupate in shallow underground chambers. The pupae are very dark, elongated, and have small spines. The pupa ends in a small forked point. Much of their time is spent in a pupal stage.
Adult (Imago)
When the imago (adult) ecloses, it has small wings which it has to pump full of fluid in order for them to expand and allow for flight. Adult rosy maple moths are distinguishable by their bright pink and yellow color, although exact coloration can vary significantly.
Diet
Larval Diet
As the name implies, rosy maple moth caterpillars mainly feed on Maples, particularly Red Maple, Silver Maple, and Sugar Maple. The emerging caterpillars, also known as the greenstriped mapleworm, mainly feed on the leaves of their host maple trees. The larvae primarily eat the underside of leaves, therefore preferentially staying in that location of their home tree. Since the caterpillars eat the entire leaf blade, in dense populations, caterpillars have been known to defoliate trees, resulting in aesthetic rather than permanent damage.
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Adult Diet
Adult Rosy Maple Moths do not eat. Instead, they focus on reproduction, relying on the energy reserves they accumulated during their larval stage.
Behavior
These moths are practically nocturnal creatures and lead a solitary life, except when it comes to mating. The adult moths generally fly around during the first third of the night. Adults undergo a stage of torpidity in the morning and afternoon, after which they come out around late evening for mating.
Mating and Reproduction
The moths usually breed one to three times per season. Mating occurs at night, when females release pheromones to attract males. Females lay eggs within 24 hours of mating, i.e., the following dusk after mating. Both sexes are polygamous, choosing a new partner every time they mate.
Lifespan/Longevity
Individual rosy maple moths typically live for about two to nine months. The upper limit comes down to five months in captivity. Between hatching and adulthood, the species undergoes five instars.
Predators
The predators of the rosy maple moth and larvae mostly consist of birds including blue jays, black-capped chickadees, and tufted titmice.
Interesting Facts
- The rosy maple moth is the smallest of the silk moths.
- The caterpillars are also known as "greenstriped mapleworms" due to their distinctive appearance.
- Adult rosy maple moths do not feed.
- The rosy maple moth is not a particularly destructive pest, and defoliation caused by the larvae is usually aesthetic rather than permanent.
- Rosy maple moths exhibit aposematic behavior with their bright yellow and pink coloring.
Conservation Status
The rosy maple moth is not currently considered to be threatened or endangered.
Management
Although larval feeding generally does not cause any long-term damage, the feeding damage may be bothersome and aesthetically displeasing. Several contact and systemic insecticides (e.g., carbaryl, bifenthrin, spinosad) are effective against larvae, though this is very rarely advised or economically worthwhile. Before treating a tree chemically, consultation with an arborist or County Extension Agent is advised. Rosy maple moths lay eggs in clusters on the undersides of leaves. These can be wiped off with your finger to prevent the larvae from feeding on your tree.