Moths exhibit diverse dietary habits, varying significantly between their larval (caterpillar) and adult stages. Their food sources range from plant matter to animal products, and some adult moths do not feed at all.
Adult Moth Feeding Habits
Most adult moths primarily consume liquids, which provide energy for flight and reproduction. Nectar from flowers is a common food source, and moths often play a role in pollination as they gather these sugary fluids. Some also feed on the juices of rotting fruits, tree sap, or honeydew, a sugary liquid secreted by aphids. Certain species may even seek out unusual food sources like animal secretions, such as bird droppings or animal dung, to obtain necessary nutrients like sodium.
Adult moths focus on liquid meals to sustain their short lifespan, which is dedicated to reproduction. They do not typically consume solid foods. The hummingbird hawk-moth, for example, sips nectar while hovering. Some specialized moths, like certain Calyptra species, have evolved to pierce animal skin and drink blood.
The Diet of Moth Larvae
The larval stage, known as a caterpillar, is the primary feeding and growth phase for moths, and their diet differs significantly from adults. Caterpillars are voracious eaters, consuming large amounts of food to build energy reserves for their transformation. Their diets are incredibly diverse, often specializing in specific host plants or materials.
Many moth larvae are herbivorous, feeding on various plant parts, including leaves, stems, flowers, and roots. The silkworm moth caterpillar, for example, exclusively eats mulberry leaves. Other larvae consume household items, becoming pests. Clothes moth larvae feed on natural fibers like wool, silk, fur, felt, and leather, which contain keratin, causing considerable damage to clothing, carpets, and upholstery.
Pantry moth larvae, including the Indian meal moth and Mediterranean flour moth, target stored dry goods. Their diets include grains, cereals, flour, dried fruits, nuts, seeds, pasta, and pet food. These larvae can chew through plastic bags and thin cardboard to access food items. Some moth larvae also feed on fungi, lichens, or decaying organic matter.
Moths That Do Not Feed
Some adult moth species do not feed at all during their adult lives, relying entirely on energy reserves accumulated as caterpillars. Large silk moths, such as the Luna and Atlas moths, lack functional mouthparts and digestive systems as adults.
Their adult lifespan is typically very short, often lasting only a few days or weeks, with reproduction as their sole purpose. The substantial fat reserves built during their larval stage are sufficient to fuel their flight and mating activities. This evolutionary strategy allows them to dedicate all their adult energy to finding a mate and laying eggs without the need to forage for food.
How Moths Consume Food
Adult moths that feed typically possess a specialized mouthpart called a proboscis, adapted for consuming liquids. This long, tube-like structure is usually coiled beneath the moth’s head when not in use. When a moth detects a food source, it unfurls its proboscis and inserts it into the liquid, effectively using it like a straw to draw in nectar, fruit juices, or other fluids. The proboscis contains muscles that allow for its extension and retraction, and its internal structure, composed of two concave tubes, facilitates the suction of moisture into the digestive tract.
Moths use their visual sense to target the nectary within flowers. They may also employ tactile sensing with their proboscis to explore the flower’s surface and locate the tiny opening where nectar is found. In contrast, moth larvae have chewing mouthparts, including a labrum (an upper lip) and strong mandibles, which enable them to tear and chew solid food like leaves or fibers. This difference in mouthparts highlights the distinct feeding strategies between the larval and adult stages of a moth’s life cycle.