Sweater-Eater Lad

Kelly’s Field Notes

Common Name: Dermestid Beetles

Order: Coleoptera

Family: Dermestidae (Skin/Hide)

Species of Note Near You (There are over 1800 species of dermestid beetle! ):

• Carpet beetle (Attagenus unicolor, Anthrenus flavipes, Anthrenus verbasci) - found in your house, eating your animal matter such as pet hair, silk, feathers, wool, felt, fur, etc.

• Hide beetle (Dermestes maculatus) - found on all continents save Antarctica, they feed on animal bodies often reducing them to skeletons. This species is used in forensic science to estimate postmortem interval (time since death) in cases involving human death. These are the beetles Producer Derek keeps on his desk.

• Tissue paper beetle (Thylodrias contractus) - the only beetle in its genus, these little guys do not eat tissue paper but do consume animal products such as wool, silk, meat, etc. Females are larviform, or never resemble adults despite reaching adulthood.

• Larder beetle (Dermestes lardarius) - found on all continents save Antarctica, they consume animal products such as pet food, dried meat, hides, feathers, etc. 

Description: 

Dermestid beetles are fairly small, between 0.1 and 1.2 cm (0.04 - 0.5 in) in length. Carpet beetles are pretty tiny, only a few mm in length, hide beetles are larger at about 0.5 - 1 cm (0.2 - 0.4 in). They tend to come in shades of brown, tan, black, or a blend of white, tan and orange. Their elytra are often very scaly which can create interesting patterns, such as in the carpet beetles. Adults are oval in shape and feed on pollen and nectar. Larvae look like spiky brushes, covered in dense, long setae (bristles) to longer thinner grubs with less densely packed setae.

Life Cycle: 

Carpet Beetle

Female adult carpet beetles lay between 30 and 100 eggs, depending on species, which hatch in about one to two weeks. The larvae are covered in dense hair (setae) and spend their time feeding on animal matter (they do not feed on synthetic material). Depending on environmental conditions, this stage can last from about 60 days to a year. When the larvae have fed enough they become a pupa, which lasts for between 10 and 17 days. Adult beetles can live for between 20 and 60 days. Depending on the species, they may only have one generation, but some do have three to four a year.

Common places for carpet beetle eggs and larvae are between your wall and floorboard, in your linens, dresser drawers, air ducts, under furniture, and in unprotected cereals, flours, and other dry goods. In the wild, adults can be found on flowers consuming pollen while their offspring are in rodent nests, bird nests, and other spaces they can readily feed on fur and feathers.

Hide Beetles

It starts with a corpse. First, males are attracted to a decaying animal body. The male pheromones and when the body is at a specific stage of decomposition attracts virgin females. The male and female then mate multiple times before she lays between three and 20 eggs, 24 hours later. Over her entire lifetime she can lay between 198 to 845 eggs. Larvae will undergo five to 11 instars, which can take five to 6 weeks, or longer depending on conditions. The larvae will then find a safe space to pupate or will be consumed by other larvae. Pupation takes about 7 or 8 days, but again can be delayed up to 20 days if conditions are unfavorable. Adults live between four and six months.

Depending on what the insect and carrion feeding community looks like, and the weather, it can take around a month for a 100lb corpse to be reduced to bones.

Super Powers:

• Flight - these guys can and do fly. 

• Barbed Bristles - some species of dermestid beetles larvae have hastisetae, which are barbed setae that can detach and entangle predators. They can also cause health issues in humans when inhaled, cause vomiting and diarrhea if ingested, and dermatitis if touched.

• Clean Up Crew - hide beetles can consume animals down to the bone and are often used in museums to clean specimens for mounting.

• Solving Cases - hide beetles are often used in forensic entomology to determine the time of death of humans where bodies are found. Testing their shed skins can also be used in toxicology reports. One French study, looking at over 1,000 cases, found 8 species of dermestid beetles on bodies.

Dermestid Beetles in Culture:

• Carpet beetles are common pests in homes all over the world. While it can be difficult to tell if the holes in your clothes come from beetles or clothes moths, carpet beetle larvae tend to create large focused holes in one area. They prefer to feed in dark undisturbed spaces, like under beds or along the edges of the floor. Thorough vacuuming is often the best method of control. 

• Hide beetles are used to clean museum specimens for mounting. They are also often used by hobbyist taxidermists for the same reason. They are easy to keep as pets and can be fed meat and vegetable scraps. 

• Hide beetles are considered a pest in the silk industry and can cause damage to cork, plaster, timber, and cotton when boring into them to pupate. Several other dermestid beetle species are also stored product pests in warehouses.

References:

“Carpet Beetle Management Guidelines--UC IPM.” Ipm.ucanr.edu, ipm.ucanr.edu/PMG/PESTNOTES/pn7436.html.

Charabidze, Damien, et al. "Involvement of larder beetles (Coleoptera: Dermestidae) on human cadavers: a review of 81 forensic cases." International Journal of Legal Medicine 128 (2014): 1021-1030.

“Dermestid Carpet Beetles - Oklahoma State University.” Extension.okstate.edu, 21 Apr. 2021, extension.okstate.edu/programs/digital-diagnostics/insects-and-arthropods/dermestid-carpet-beetles. Accessed 29 Mar. 2024.

“Dermestidae.” Wikipedia, 12 Feb. 2023, en.wikipedia.org/wiki/Dermestidae.

‌“EENY466/IN836: Hide Beetle Dermestes maculatus DeGeer.” Ask IFAS - Powered by EDIS, edis.ifas.ufl.edu/publication/IN836.

Sonker, R., Rawat, S., and Singh, K. "Succession and life cycle of beetles on the exposed carcass." Int J Sci Innov Res 1.3 (2015): 46-50.