The Atlas moth, Attacus atlas, is one of the largest Lepidopterans globally, recognized for its impressive size and striking wing patterns. Found across the tropical and subtropical forests of Southeast Asia, its wingspan can reach up to 30 centimeters, comparable to a small bird. The common name may refer to the map-like patterns on its wings or to the Titan of Greek mythology, Atlas, due to its scale. It is also called the “snake’s head moth” because the prominent extensions at the tips of the forewings resemble a cobra’s head.
The Voracious Larval Stage: Host Plants
The Atlas moth’s diet is confined entirely to its larval stage, where the creature exists as a massive, pale-green caterpillar. This phase is characterized by consumption, as the larva must accumulate all the energy reserves required for its entire life cycle. The caterpillar is a generalist feeder, utilizing a wide variety of host plants found in its native habitat.
Its diet includes the foliage of several tree species, such as cinnamon (Cinnamomum), guava (Psidium), and various citrus plants. Other food sources include willow (Salix) and plants from the Annona genus, like sugar apple. The caterpillar grows to an imposing size, reaching lengths of up to 11.5 centimeters and a thickness of approximately 2.5 centimeters. The stored fat powers the subsequent pupal and adult stages of development.
The Adult Moth: A Life Without Eating
The adult Atlas moth is completely unable to consume any food, a trait shared by many large silk moths. This lack of feeding is due to a biological transformation during pupation.
The adult insect possesses only vestigial mouthparts. Its proboscis—the tube-like structure used by many other moths and butterflies to drink nectar—is tiny and non-functional. Consequently, the adult moth cannot ingest liquids or solids. The entire adult lifespan is sustained solely by the fat reserves built up during the caterpillar phase.
The adult stage is entirely dedicated to reproduction, not growth or foraging. Every movement, including flight, expends the finite energy supply carried over from its larval form. To conserve fuel, the moths are weak, unsteady flyers that remain motionless during the day, only becoming active at night to seek a mate.
Fueling Reproduction: The Atlas Moth Life Cycle
The Atlas moth’s life cycle contrasts the long, feeding larval stage with the brief, reproductive adult phase. Following the weeks-long period of intensive growth, the caterpillar spins a silken cocoon in which it pupates. After approximately four weeks inside the cocoon, the adult moth emerges with a singular purpose.
The adult’s existence is extremely short, typically lasting only one to two weeks. This short duration is a direct consequence of its inability to replenish energy stores. The male moth must quickly locate a female, detecting her pheromones from a long distance using his large, feathery antennae. The female, noticeably larger than the male, will then lay her eggs, ensuring the next generation before her stored energy is depleted.