COMET MOTH

Characteristics

The comet moth, also known as the Madagascan moon moth, is the one of the largest species of silk moths (family Saturniidae) and is only found in rainforests in Madagascar. The name comet moth comes from their “tails,” elongated parts of the lower wings that resemble the streaks trailing behind a comet. Males and females look very similar, although the female’s wings are more rounded. The most notable difference is the long, feathery antennae of the males.

Like many other species of Saturniidae, the comet moth has eyespots on its wings. These give the moth its genus name, Argema, meaning “speckled eye” in Greek. These eyespots are thought to surprise or confuse predators, making the moth seem larger than it is and seem to be “watching.” Because this moth is typically a night-flying insect, it might seem odd that it is so brightly colored in red and yellow. But in its native rainforest habitat, those colors and the patterns on its wings actually help camouflage it during the day. If it were sitting still against a background of leaves, flowers, and fruits, you could probably pass by it several times without spotting it.

Behavior

The comet moth’s long, red-and-yellow “tails” are a beautiful feature, but they have a useful purpose as well: they are thought to be used in defense. Studies have shown that the tails are good at diverting the attacks of bats! It seems that the tails spinning behind the moth as it is flying interferes with a bat’s echolocation, luring the bat to attack the tails rather than the moth’s body. The moth doesn’t really need the tails to fly, and because it only lives as an adult for about a week, it’s better to lose the tails and live to reproduce another day.

With only a few days as adults, comet moths have to make the most of their time. For one thing, they don’t eat—they are referred to as a “moth without a mouth.” They do actually have a mouth and a gut, but neither is functional. Rather than spending time looking for food, comet moths live on the energy stored from what they consumed as a caterpillar!

After emerging from their cocoon, it’s a race to reproduce. The males must take the initiative to find a mate; the females tend to stay in one location, waiting to be found. Since time is short, the males have built-in radar to help them: their large antennae. The feathery plumes increase the surface area, making it easier to catch molecules of a female’s pheromone wafting on the breeze. He then follows the scent to locate her. The antennae are quite an effective tool—males are thought to be able to sense females from miles away.

Reproduction and Life Cycle

After a female has mated, she will lay 120 to 170 eggs on proper host plants, mainly eucalyptus. The eggs are small and round, and they hatch in 10 to 20 days. The caterpillars are voracious eaters—storing up the fat and nutrients they will live on as adults—and they grow at a rapid rate, turning bright green as they get larger.

Once a caterpillar has reached the appropriate size, it spins a cocoon made of silky threads affixed to a sturdy stem or branch. The cocoon resembles a grayish-white sack. But it has a handy feature adapted for its wet rainforest environment: it is loosely woven with many holes, which allows rainwater to go through it, rather than accumulating inside and drowning the pupa!

Conservation and Threats

As with so many of Madagascar’s species, the comet moth is threatened by deforestation and habitat loss. Its survival depends on protecting the rainforests where it is uniquely adapted to live.