Moths generally do not attack or bite humans. The idea that these insects are aggressive is a common misconception, as most adult moths lack the physiological mechanisms to inflict harm. While some rare species possess specialized mouthparts or defensive hairs, the vast majority are harmless to humans.
Moth Behavior Towards Humans
Most adult moths do not bite or sting, as they lack the necessary mouthparts. Many have a proboscis for sipping liquids like nectar. Some species do not feed as adults, relying on energy reserves from their larval stage.
Moths are primarily nocturnal and attracted to artificial light. This positive phototaxis often causes them to fly erratically around lights, sometimes bumping into people. This is navigational confusion, not aggression. Their focus is on feeding or reproduction.
Moths may fly towards faces or bodies due to factors like body heat, carbon dioxide, or scents. These are accidental encounters or an attraction to human environmental cues, not deliberate pursuit. Moths do not chase people or nest in human hair.
Rare exceptions exist, such as “vampire moths” (genus Calyptra) in parts of Asia, Africa, and Europe, whose males can pierce skin to feed on blood. However, these are not common household pests and are geographically restricted.
Real Concerns and Nuisances
While adult moths generally pose no direct threat, their larvae, or caterpillars, can cause various issues. Certain moth larvae possess defensive hairs or spines that, upon contact, can cause skin irritation, rashes, or allergic reactions in humans. This condition, known as lepidopterism or caterpillar dermatitis, can manifest as itching, redness, swelling, and sometimes blistering. The hairs of some species, like the browntail moth caterpillar, contain toxins and can remain irritating in the environment for an extended period.
Moths can also become a nuisance through property damage, particularly by their larval stages. Clothes moths, such as the webbing clothes moth and casemaking clothes moth, cause holes and thinning in natural fibers like wool, silk, fur, and leather. The larvae feed on keratin, a protein found in these materials, and can extensively damage garments and upholstery if undetected.
Pantry moths, including the Indian meal moth, infest stored dry goods such as grains, cereals, nuts, and dried fruits. The larvae contaminate food with their webbing, droppings, and shed skins, making it aesthetically unacceptable. While accidentally consuming pantry moths or their larvae is generally not harmful to human health, it indicates food contamination and necessitates discarding infested items.