Dermestid Beetle

Wayne and Gladys Valley Children's Zoo


In the Zoo
9-14 mm
9-14 mm
350 pounds Maturity: 30 years

Geographic Range

North America

Scientific Information

Scientific Name:
Dermestes marmoratus

Lifestyle and Lifespan

Activity Time Frame:
Sexual Dimorphism:
60 days gestation, 8 month incubation Lifespan in the Wild: 70+ years
Lifespan in the Wild:
2-3 years
Lifespan in Captivity:
2-3 years


Not Evaluated


Of the 500 species of dermestid beetles worldwide, 123 live in North America. They are sometimes called museum beetles, bow bugs, or carpet beetles, depending on where they are found and what they eat.

Species Specifics

This is the largest dermestid in California with a length of 9 to 14 mm. An adult has a slightly flattened elongated oval carapace. It is black with gray scales forming spots and a broad band across the base of the wing covers. The underside is mostly whitish. Larvae are elongated and reddish brown with a pale stripe down the back. They are covered with long reddish brown hairs.

Physical Characteristics

The hair of the larvae break off readily and cause irritation of tender skin (e.g. in a bird’s mouth), thus acting as a defense mechanism. Coleoptera means sheathed wing. Beetles have their forewings strengthened and hardened with a special material called chitin as protective covers for the operative under pair.



Low to middle elevations in North America.


The Gila monster ranges from extreme southwestern Utah, southern Nevada and adjacent to San Bernadino County, California; southeastward through west and south Arizona and southwestern New Mexico. It can be found south into Mexico through Sonora to northwestern Sinaloa. It ranges from sea level to 1500 meters in altitude.


Dermestid beetles feed on decaying flesh but have expanded their diet to include human-made items. Beetles of the Dermestidae family feed on a great many things such as cereal products, grains, rugs and carpets, various stored foods, upholstery, fur coats, etc. and thus most are considered destructive pests. Some dermestids are harmful in museums since they may feed on mounted birds or mammals and specimens of plants and insects, while other dermestids are employed by museums to clean skeletons for exhibits.

Ecological Web

Dermestid beetles show up on carcasses when they start to dry-out. They break down and decompose decaying flesh which helps keep ecosystems clean and healthy. They will also eat fresh carcasses in captivity but in the wild they are pushed out by more aggressive maggots who need more moist food.

Activity and Behavior

Activity Pattern

Active in the day time periods and throughout spring and summer, retreating to burrows during the fall and winter months for brumation.


Once they bite, they will not usually let go on their own and must be pulled off. The longer this takes, the more venom they will excrete into the bite! Unlike most lizards, they come out at night!

Social Behavior

Solitary. Although monitors are not social, neither are they territorial. Bipedal ritual combat has been observed in the trees during the breeding season. Since their tails are so important, they defend their tails, rather than use them as whips. Black Tree Monitors in the wild are reported to be nervous and high-strung; they will flee if threatened, and if handled carelessly, will scratch, bite and then defecate on the offender.

Reproductive Behavior

Adult female insects emerge from the pupa with a full complement of eggs retained in the ovaries. Sperm introduced by the male is stored and released as the eggs pass out through the ovipositor. This beetle’s eggs are usually deposited in carrion.


Beetles lay eggs which produce larvae quite different in form from the adult. When full-size, such larvae undergo a further change of form to become a pupa which is inert and does not feed. The pupa undergoes metamorphosis and emerges as the adult. Adult female insects emerge from the pupa with a full complement of eggs retained in the ovaries. Sperm introduced by the male is stored and released as the eggs pass out through the ovipositor. This beetle’s eggs are usually deposited in carrion.



Not listed as endangered. (Listed as Data Deficient by IUCN.) But, it is vulnerable to loss of habitat due to the deforestation prevalent within its small, restricted range. It is also popular in the pet trade, with most specimens being captured from the wild, because they need so much room to breed in captivity.


It is thought dermestid beetles were introduced into California by hide traders in the early days.

Current Threats

Introduced Non-Native, Domestic, and Invasive Species

Our Role

Oakland Zoo exhibits dermestid beetles in the Bug House and educates the public about their role in ecosystems. At Halloween time, we have a special exhibit at our event, Boo at the Zoo, where you can see many different carcasses being eaten by dermestid beetles.

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Fascinating Facts

The name "dermestid" comes from the Greek word for "skin," a perfect name considering their favorite food.

Dermestid beetles are used to clean bones for zoo and museum displays, as well as in forensic investigations. Chemicals can also be used to clean bones but they can sometimes cause damage to marks or wounds on the bones.

Beetles typify the success of insects. This order contains not only the most numerous species (over 330,000 worldwide) of the insects, but also of the animal kingdom.


VanClay, Mary. "Bow Bugs, Dermestids." Johnson String Instrument.