Moths, a diverse group of insects, exhibit a wide array of feeding behaviors. Their diets are highly dependent on both the species and their specific life stage. Understanding what moths consume provides insight into their ecological roles, from pollination to decomposition.
Adult Moth Diets
Adult moths primarily sustain themselves on liquid diets, utilizing a specialized mouthpart called a proboscis. This straw-like structure allows them to sip fluids. Most adult moths are nectar feeders, extending their proboscis into flowers to access sugary nectar, which provides energy for flight and reproduction. This feeding behavior also makes them important pollinators for many plants.
Beyond nectar, adult moths consume other sugary liquids. They are attracted to juices of ripe or fermenting fruits, and some can pierce fruit skin. Tree sap is another food source, with certain moths tapping into sugary excretions from wounded trees. Honeydew, a sugary byproduct secreted by aphids, also serves as food.
Some species, known as saprophagous moths, feed on decaying organic matter like fungi or rotting plant material, contributing to nutrient recycling. Certain moths may obtain nutrients from bird droppings or animal dung.
Caterpillars’ Food Sources
The larval stage of moths, known as caterpillars, is the primary feeding period for growth and energy storage before metamorphosis. Unlike adult moths, caterpillars possess chewing mouthparts, allowing them to consume solid food. Most caterpillars are herbivorous, feeding on various plant parts, including leaves, stems, flowers, and roots.
Some caterpillars are generalists, consuming a wide range of plants, while others are specialized, feeding exclusively on specific plant species. For instance, silkworm moth caterpillars (Bombyx mori) feed solely on mulberry leaves. Other moth larvae consume materials beyond living plant matter. Clothes moth larvae, such as the common clothes moth, feed on natural animal fibers like wool, silk, fur, and feathers. These materials contain keratin, a protein the larvae can digest, making them a household pest.
Pantry moth larvae, including the Indian meal moth, target stored dry goods such as grains, cereals, flour, nuts, dried fruits, and pet food. They can chew through packaging and contaminate food with webbing and feces. Unusual caterpillar diets include wood, as seen in carpenter moths, and even the shells of dead gopher tortoises or other insects for some carnivorous species.
Moths That Do Not Feed
Some moth species do not feed during their adult stage. These moths, often large and striking, rely entirely on energy reserves accumulated as caterpillars to fuel their brief adult lives. Their primary purpose upon emerging as adults is reproduction, as they do not possess functional mouthparts or a digestive system.
Species like the Luna moth (Actias luna), Atlas moth, and other giant silk moths (Saturniidae family) exemplify this non-feeding strategy. Their adult lifespan is very short, lasting only about one week, just long enough to find a mate and lay eggs. The energy stored as fat during their voracious caterpillar stage is sufficient to sustain them through this reproductive phase. This adaptation allows them to focus solely on perpetuating their species without expending energy on foraging.