Moths (order Lepidoptera) are generally known for their delicate nature and a diet centered on sweet liquids like floral nectar. However, the question of whether these insects consume blood yields a surprising answer: yes, a few specialized species have developed this rare behavior. This unusual adaptation is not a general trait of the over 160,000 moth species worldwide, but rather a unique feeding strategy employed by a select group.
Specific Moths That Drink Blood
The moths responsible for this blood-drinking behavior belong primarily to the genus Calyptra, often informally called Vampire Moths. This behavior has been documented in at least ten of the eighteen species within this genus, which is distributed across Europe, Africa, and Asia. The blood-feeding trait is most common in certain regions of Southeast Asia and the Russian Far East.
The ability to pierce skin and consume blood is almost exclusively exhibited by the adult male moths, such as Calyptra thalictri. Females of these species generally stick to their primary diet, but the males have adapted this specific behavior to gain a nutritional advantage.
The Unique Nutritional Motivation
The driving force behind this hematophagy (blood-feeding) is a biological requirement for specific nutrients, particularly sodium and other mineral salts. These essential minerals are scarce in the moth’s usual diet of fruit juices and nectar, which are high in sugar but low in salt. Males use the acquired sodium to create a nutrient-rich spermatophore, a package of sperm and nourishment, which is passed to the female during mating.
This transfer provides a significant nutritional boost to the female, enhancing the viability of her eggs and the survival rate of the next generation. The Calyptra possess a highly specialized proboscis, the long, straw-like mouthpart common to Lepidoptera. Unlike the soft proboscis of most moths, the Calyptra proboscis has a hardened, hooked, and barbed tip.
This specialized tip allows the moth to pierce the tough skin of fruit or the hide of a vertebrate host. The moth uses a distinctive rocking motion to drill the proboscis into the skin, sometimes anchoring itself to feed for an extended period. This skin-piercing ability is thought to have evolved from their pre-existing ability to pierce the rind of hard fruits.
The Typical Moth Diet
The occasional blood-feeding of Calyptra is an extreme exception in a group defined by a much softer palate. The vast majority of adult moths feed primarily on nectar, using their proboscis to sip liquids from flowers, making them important nocturnal pollinators. They are especially important for night-blooming plants, whose pale or white flowers are more easily located in the dark.
Beyond nectar, many species obtain sustenance from tree sap, the juices of fermenting or rotting fruit, or animal excretions to gain trace minerals. Some of the largest moth species, such as the giant silk moths, do not feed at all as adults. These non-feeding adults rely solely on energy reserves built up during their caterpillar stage and lack functional mouthparts, focusing entirely on reproduction.