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varied carpet beetle

Anthrenus verbasci

What do they look like?

Adult varied carpet beetles are 2-3 mm long and shaped like ovals. Adult varied carpet beetles have wings. The top side is covered in small scales of brownish-yellow, white, and black color. The white scales make up patterns that form three wavy bands. The bottom side has scales of greyish-yellow color. Varied carpet beetles are different than other beetles in their genus (Anthrenus) in having body scales more than twice as long as they are wide. (Bousquet, 1990; Robinson, 2005; Shetlar, 2011)

Full-grown larval varied carpet beetles are 4-5 mm long. They are covered in tufts of hairs. Their bodies are narrow in the front and broad in the rear. They have hairs that form light- and dark-brown stripes across their bodies. Closely packed hairs cover each side of their back end. (Robinson, 2005; Shetlar, 2011)

  • Range length
    2 to 3 mm
    0.08 to 0.12 in

Where do they live?

Varied carpet beetles (Anthrenus verbasci) are a species of beetle that can be found all around the world. They live indoors and outdoors, anywhere that they can find a lot of food. Varied carpet beetles are from Europe, Asia, and North Africa, but came to North America around 1850. (Abdel-Dayem, et al., 2017; Bousquet, 1990; Majka, 2007; Robinson, 2005)

What kind of habitat do they need?

Varied carpet beetles can live anywhere that they can find food. As long as they have warm temperatures, food, and light, they can survive. Outdoor adult varied carpet beetles are found on flowering plants like meadowsweets. They live in wasp nests in attics and under the siding of homes. Outdoor larvae can be in the nests of birds, such as sparrows, starlings, corvids, swifts, and in bat roosts. (Bousquet, 1990; Majka, 2007; Robinson, 2005)

Indoor varied carpet beetles are a household pest. They are found in stored food materials, plant materials (dried fruit and nuts), and animal materials (wool, fur, and skins). Indoor larvae are known to eat dried insect collections and silkworm moth cocoons. They can be found in dried-milk factories, warehouses, and sometimes in flour mills. (Bousquet, 1990; Majka, 2007; Robinson, 2005)

How do they grow?

Eggs are laid individually or in batches. Hatching times are dependent on temperature, lasting 30–35 days at 18 ◦C and decreasing to 10–12 days at 29 ◦C. Larval development is affected by temperature, relative humidity, and food quality; typically taking 222-323 days at a temperature between 15–25 ◦C. The last larval skin serves as the pupal case for pupation; adults remain inactive for 1-8 days before emerging from the case. The pupal period lasts 17–19 days at 18 ◦C and decreases with increasing temperature to 7–8 days at 29 ◦C. Adults live and reproduce 20-60 days after emerging from pupation. (Blake, 1961; Robinson, 2005)

Pupation occurs in a circannual rhythm. The periodicity of pupation is dependent on the temperature and environment. Diapause depends on temperature; one diapause occurs at 25 ◦C with complete development in one year, while two diapause stages occur at 15 ◦C with a life cycle of 2 years. Household varied carpet beetles produce adults in the fall, while outdoor populations produce adults in the spring. (Miyazaki, et al., 2009; Robinson, 2005)

Female beetles lay eggs in singles or in batches. The time it takes to hatch depends on the temperature. The warmer it is, the faster the eggs hatch. It only takes 10-12 days for the eggs to hatch at 29◦C. Larval development depends on temperature, humidity, and food quality. It takes 222-323 days at a temperature between 15–25◦C. The larvae eat until they are fully grown, then they go through metamorphosis. Adults leave the cocoon 1-8 days later. As temperature increases, the length of time spent going through metamorphosis shortens. Adults live and reproduce 20-60 days after leaving the cocoon. (Blake, 1961; Robinson, 2005)

Metamorphosis happens around the same time each year. The specific time it happens depends on the temperature and environment. Household adult carpet beetles produce adults in the fall. Field populations produce adults in the spring. (Miyazaki, et al., 2009; Robinson, 2005)

How do they reproduce?

Copulation can last from 1-9 minutes. Males and females take multiple mates. (Wojcik, 1969)

Varied carpet beetles live and reproduce for 20-60 days after undergoing metamorphosis. Adult varied carpet beetles from outdoor populations are always attracted to light. They will mate on the plants that they eat during the daytime. Those from indoor populations are only attracted to light when they are ready to mate. They will look for somewhere well lit to mate. Adult beetles do not require food or water to reproduce. Female beetles carry the eggs and lay them in singles or in batches. (Blake, 1961; Robinson, 2005)

  • How often does reproduction occur?
    Varied carpet beetles breed yearly.
  • Breeding season
    Varied carpet beetles breed in spring and early summer.
  • Range eggs per season
    50 (high)
  • Range gestation period
    4 to 35 days
  • Average gestation period
    18 days
  • Average time to independence
    0 minutes
  • Range age at sexual or reproductive maturity (female)
    1 to 2 years
  • Range age at sexual or reproductive maturity (male)
    1 to 2 years

No parental involvement occurs. (Robinson, 2005)

  • Parental Investment
  • no parental involvement

How long do they live?

The life cycle of varied carpet beetles ranges from 1-2 years depending on temperatures. Low temperatures make the larval stage and metamorphosis last longer. High temperatures shorten the time spent in development. Outdoor varied carpet beetles have longer lifespans because winter temperatures slow down their rate of development. (Blake, 1958; Robinson, 2005)

  • Range lifespan
    Status: wild
    2+ (high) years
  • Typical lifespan
    Status: wild
    1 to 2 years

How do they behave?

Varied carpet beetles live in colonies. Indoor colonies can get into stores of food. Adults can fly, but they like to stay close to their homes. (Robinson, 2005)

How do they communicate with each other?

Varied carpet beetles use their sense of sight, touch, and chemical receptors to get information. They use pheromones to find mates. (Mayer, 2019; Wojcik, 1969)

What do they eat?

Indoor populations feed on stored food materials, such as wheat, maize, oats, rice, biscuits, cakes, seeds, cayenne pepper, cacao, and dried cheese. They also feed on wool, fur, skins, and are known to feed on insect collections and silkworm cocoons. Outdoor populations of adult varied carpet beetles feed primarily on pollen and nectar from the meadowsweet genus, but also from the hogweed, chervil, ground elder, umbellifer, yarrow, chamomile genera, and the daisy family. (Majka, 2007; Robinson, 2005)

  • Animal Foods
  • insects
  • Plant Foods
  • seeds, grains, and nuts
  • fruit
  • pollen
  • flowers

What eats them and how do they avoid being eaten?

Adult parasitoid wasps in the family Bethylidae are predators of varied carpet beetles. (Robinson, 2005)

Adult wasps in the family Bethylidae are predators of varied carpet beetles. (Robinson, 2005)

  • Known Predators

What roles do they have in the ecosystem?

Adult varied carpet beetles are pollinators of the species of plants they feed and mate on. Parasitic wasps (Bethylidae) have been recorded. (Robinson, 2005)

  • Ecosystem Impact
  • pollinates
Commensal or parasitic species (or larger taxonomic groups) that use this species as a host

Do they cause problems?

Varied carpet beetles are a well-known household pest. They are known to infest factories, museums, and warehouses. Often feeding on dried food stores and animal products, they destroy household goods. (Bousquet, 1990; Robinson, 2005)

  • Ways that these animals might be a problem for humans
  • household pest

How do they interact with us?

Varied carpet beetles are a pollinator of flowering plants. (Robinson, 2005)

  • Ways that people benefit from these animals:
  • pollinates crops

Are they endangered?

Contributors

Deena Hauze (author), Animal Diversity Web Staff.

References

Abdel-Dayem, M., H. Fad, A. El-Torkey, A. Elgharbawy, Y. Aldryhim, B. Kondratieff, A. Al Ansi, H. Aldhafer. 2017. The beetle fauna (Insecta, Coleoptera) of the Rawdhat Khorim National Park, Central Saudi Arabia. ZooKeys, 653: 1-78. Accessed April 26, 2020 at https://zookeys.pensoft.net/article/10252/list/9/.

Blake, G. 1958. Diapause and the Regulation of Development in Anthrenus verbasci (L.) (Col., Dermestidae). Bulletin of Entomological Research, 49(4): 751-775.

Blake, G. 1961. Length of life, fecundity and the oviposition cycle in Anthrenus verbasci (L.) (Col., Dermestidae) as affected by adult diet.. Bulletin of Entomological Research, 52(3): 459-472.

Bousquet, Y. 1990. Beetles Associated with Stored Products in Canada: An identification guide. Ottawa: Research Branch Agriculture Canada, Publication 1837.

Majka, C. 2007. The Derodontidae, Dermestidae, Bostrichidae, and Anobiidae of the Maritime Provinces of Canada (Coleoptera: Bostrichiformia). Zootaxa, 1573: 1-38. Accessed April 26, 2020 at https://www.researchgate.net/publication/228385936_The_Derodontidae_Dermestidae_Bostrichidae_and_Anobiidae_of_the_Maritime_Provinces_of_Canada_Coleoptera_Bostrichiformia.

Mayer, M. 2019. Handbook of Insect Pheromones and Sex Attractants. Boca Raton: CRC Press.

Miyazaki, Y., T. Nisimura, H. Numata. 2009. A circadian system is involved in photoperiodic entrainment of the circannual rhythm of Anthrenus verbasci. Journal of Insect Physiology, 55 (4): 494-498. Accessed April 26, 2020 at https://doi.org/10.1016/j.jinsphys.2008.12.003.

Robinson, W. 2005. Urban Insects and Arachnids: A Handbook of Urban Entomology. Cambridge: Cambridge University Press. Accessed April 24, 2020 at http://www.bio-nica.info/biblioteca/Robinson2005UrbanInsects.pdf.

Shetlar, D. 2011. "Carpet Beetles" (On-line). Ohioline. Accessed April 24, 2020 at https://ohioline.osu.edu/factsheet/HYG-2103-10.

Wojcik, D. 1969. Mating Behavior of 8 Stored-Product Beetles (Coleoptera: Dermestidae, Tenebrionidae, Cucujidae, and Curculionidae). Florida Entomologist, 52(3): 174-176. Accessed April 29, 2020 at https://journals.flvc.org/flaent/article/view/56506/54185.

 
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Hauze, D. 2020. "Anthrenus verbasci" (On-line), Animal Diversity Web. Accessed October 22, 2021 at http://www.biokids.umich.edu/accounts/Anthrenus_verbasci/

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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