Moths belong to the order Lepidoptera, encompassing over 160,000 described species globally. Their dietary habits are complex because they undergo complete metamorphosis, resulting in distinct feeding strategies across their four life stages: egg, larva, pupa, and adult. The most dramatic difference in diet exists between the larval stage, focused entirely on growth, and the adult stage, focused on reproduction and dispersal. What a moth “eats” is entirely dependent on its current biological form and the specific species.
The Primary Eaters: Larval Diet
The caterpillar, or larval stage, is the phase where nearly all feeding and growth occurs. The vast majority of moth caterpillars are phytophagous, meaning they feed on plant material. Their diets are varied, ranging from chewing leaves and boring into woody stems to consuming roots, seeds, and flower tissues. Many species are highly specialized, feeding only on a single plant type, while others are generalists that consume a wide array of vegetation.
Beyond plant-based diets, some species consume materials indigestible to most other organisms. For instance, clothes moth larvae, such as the webbing clothes moth (Tineola bisselliella), digest keratin. This protein is the main component of wool, hair, feathers, and silk, allowing them to thrive on items like woolen clothing and natural fiber carpets. Pantry moth larvae, notably the Indianmeal moth (Plodia interpunctella), infest stored dry goods, consuming grains, flour, nuts, dried fruits, and cereals. A few exceptional species are also predatory, actively hunting smaller insects or other caterpillars.
Adult Moth Feeding Habits
For adult moths with functional mouthparts, feeding shifts from growth to energy maintenance for flight and reproduction. These moths utilize a coiled, straw-like proboscis to sip liquids, as they cannot chew solid food. Their caloric intake comes from liquid sugar sources that fuel their active lifestyle.
Nectar is a common food source, particularly for hawk moths, which are significant pollinators of night-blooming flowers. Other adult moths seek sugary liquids from non-floral sources, such as tree sap flows or the fermented juices of rotting fruit. Certain species may also feed on honeydew, a sugary excretion left by sap-sucking insects like aphids. These liquid meals provide energy reserves for the adult moth’s short period of flight and mating.
The Non-Feeding Adult Stage
A number of moth species, particularly within the giant silk moth family (Saturniidae), have an adult stage that does not feed. Species like the Luna moth (Actias luna) and the Atlas moth lack a functional proboscis and possess only vestigial mouthparts. These adults cannot consume any food or water after emerging from their cocoons.
Their entire existence is fueled by the energy and fat stores accumulated during their caterpillar phase. Since they do not need to forage for food, their adult life is extremely short, often lasting only about a week. This brief period is dedicated solely to finding a mate and reproducing.
Hydration and Mineral Intake
The consumption of water and minerals is an important behavior, often achieved through a process called “puddling.” This involves adult moths, most frequently males, congregating to drink from moist substrates like damp soil, wet sand, mud, or animal scat. Puddling is not about consuming sugar for energy, but rather acquiring essential salts and nutrients that are scarce in nectar or a purely herbivorous larval diet.
The most sought-after nutrient is often sodium, which is incorporated into the male’s spermatophore during mating. This acquired sodium is transferred to the female, providing her with minerals to improve the viability and survival rate of her eggs. Moths also consume dew or rainwater for basic hydration, especially in dry environments.