The question of whether moths consume human or animal remains is complex. Moths do not feed on soft tissues like many other insects, but certain species are attracted to and feed on specific components of a body. Their presence indicates a later, drier stage of decomposition, not early decay. Forensic science uses the life cycles of these insects to help determine the time and circumstances of a death.
Moths and Keratin: The True Diet
Moths that interact with remains are specialized feeders on keratin, a tough structural protein. Keratin is a major component of hair, fingernails, dried skin, feathers, and natural fibers like wool and silk. The larvae of the Tineidae family, commonly known as clothes moths, are the primary species involved. These larvae possess unique digestive enzymes required to break down keratin, which is indigestible to most other organisms. This specialization means they only colonize a body once soft, moist tissues have been consumed or dried out, targeting dry parts like hair or remaining skin.
Moths in Forensic Entomology
The appearance of moths indicates the post-decay stage, when remains are mummified, skeletonized, or significantly dried. Forensic entomologists study their presence to help determine the Post Mortem Interval (PMI), the estimated time since death. Moths are considered secondary or tertiary decomposers because they follow the initial waves of insects that consume soft, moist tissues.
Key Species and Evidence
Moth larvae are attracted to protected, dark, and dry environments, such as inside clothing or mummified remains found indoors. The casemaking clothes moth (Tinea pellionella) and the webbing clothes moth (Tineola bisselliella) provide evidence to investigators through their larval cases and feeding activity. For example, casemaking clothes moth larvae incorporate human hair into their portable silk shelters, a behavior that can provide recoverable DNA evidence.
Contrasting Moths with Primary Decomposers
Moths operate on a different timeline and food source than the primary decomposers that first colonize a body. Insects like blowflies (family Calliphoridae) and flesh flies (family Sarcophagidae) are the initial responders, often arriving within minutes to hours of death. These flies are flesh feeders, laying eggs or depositing live larvae on moist tissues, and their maggots rapidly consume soft tissue during the early, wet stages of decomposition.
Late-Stage Clean-up
The slow, keratin-based feeding of moths contrasts sharply with the rapid consumption of carrion by fly larvae. The blowfly and flesh fly life cycles are used to estimate the PMI during the first weeks after death based on their predictable growth rates. Moths, along with dermestid beetles, arrive much later to clean up tough, dry remnants like hair and dried skin, which early decomposers cannot easily process.