Butterflies are often associated with delicate beauty and sweet floral nectar, but their diet is far more resourceful than their reputation suggests. Many species of the order Lepidoptera, which includes butterflies and moths, feed on decaying animal matter, including corpses, as part of their foraging behavior. This strategy allows them to acquire nutrients beyond the simple carbohydrates found in flowers. Fluids from carrion supplement their sugary diet, providing essential components that a typical flower-based meal lacks.
The Reason Behind Unconventional Feeding
The primary energy source for adult butterflies is nectar, which is rich in sugars needed for flight and daily activity. However, nectar is deficient in certain minerals and amino acids. These components are required for reproduction and maintaining flight muscle tissue, driving butterflies to seek alternative food sources.
Butterflies specifically need sodium, which is scarce in plant-based diets, and nitrogen, an element necessary for building amino acids and proteins. Decomposing animal matter, such as a corpse or scat, is an excellent source of these compounds because the proteins and salts are broken down into a liquid slurry. This behavior is especially common for male butterflies, who incorporate the collected nutrients into the spermatophore transferred to the female during mating.
This “nuptial gift” of essential minerals enhances the female’s reproductive success and the viability of her eggs. The consumption of decaying matter is a targeted biological imperative aimed at securing resources for the next generation. The carcass provides a concentrated source of these elements, making it an attractive feeding site.
How Butterflies Consume Non-Nectar Sources
Since butterflies cannot chew or bite solid food, their entire adult diet must consist of liquids. Their mouthpart, called a proboscis, is a long, coiled tube that functions like a straw. When the insect detects a suitable fluid source, the proboscis unfurls from beneath the butterfly’s head.
When a butterfly lands on a corpse or semi-solid material like rotting fruit, it cannot simply suck up the nutrients. It must first release specialized digestive enzymes onto the solid matter to break it down externally. These enzymes liquefy the tissue and dissolved minerals, creating a solution the butterfly can then ingest.
The proboscis is composed of two interlocking halves, or galeae, which form a central food canal. The butterfly uses a muscular sucking pump located in its head to draw the liquid up this canal. This combination of external digestion and internal suction allows the insect to harvest mineral-rich fluids from surfaces that appear solid.
Dietary Variety Beyond Nectar
The consumption of animal remains, known as necrophagy, is one example of nutrient foraging within the broader category of “puddling.” Puddling originally described butterflies gathering at moist soil or mud puddles to sip water containing dissolved salts and minerals. This is the most common way butterflies supplement their diet with sodium.
Butterflies utilize a wide range of other nutrient-dense sources to fulfill their mineral requirements. They feed on animal scat, or feces, which provides a rich concentration of nitrogenous waste and salts. Rotting fruit and tree sap are also frequently visited, as fermentation breaks down the plant material into easily digestible liquids containing micronutrients.
Some species land on mammals, including humans, to sip the salt-rich moisture from sweat or tears. This variety of unconventional feeding shows that the butterfly’s diet is highly opportunistic. It is driven by a search for the sodium and nitrogen compounds missing from sweet flower nectar.