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goldsmith beetle

Cotalpa lanigera

What do they look like?

Goldsmith beetles are yellow or green in color with a metallic gold tint. Their bodies are shaped like eggs, and are big and heavy for a bug. They are about 20 to 26 mm long. Underneath, they have whitish woolly hairs. Their hardened front wings have rows of small holes. (Coin, 2005; Lockwood, 1868)

  • Range length
    20 to 26 mm
    0.79 to 1.02 in

Where do they live?

Goldsmith beetles live in the eastern, central, and southwestern United States. They also live in southeastern Canada. (Coin, 2005)

What kind of habitat do they need?

Goldsmith beetles live in forests with trees that lose their leaves, woodlands, and fields near woodlands. (Coin, 2005)

  • These animals are found in the following types of habitat
  • terrestrial

How do they grow?

Like most beetles, goldsmith beetles transform from larvae to pupae to adults. The eggs hatch into grubs, which are whitish, C-shaped larvae. They can't move much, but they burrow to find a food source. They eat more as larvae than in other parts of their life. After 1 or 2 years, they enter the next stage of transformation, called pupae. Then, they transform again into adult beetles. (Libich, 2000; Williams, 2006)

How do they reproduce?

The mating systems of goldmith beetles are probably similar to their relatives. Most beetles use their sense of smell to help them find mates. (Libich, 2000)

Goldsmith beetles breed from April and July. The eggs grow inside the females for about 6 months, and then they lay them in clumps on top of the soil under a tree. They don't lay very many eggs compared to similar species. They stay as larvae for 1 to 2 years, and then become pupae. The adults come out from the pupa stage between May and July. (Breda, 2001; Coin, 2005; Lockwood, 1868; Williams, 2006)

  • Breeding season
    Goldsmith beetles breed from April to July.
  • Average gestation period
    6 months
  • Range time to independence
    12 to 24 months

Female goldsmith beetles lay their eggs on the soil near the roots of a tree or in rotting logs, because these are possible sources of food. Goldsmith beetles don't care for their young after the females lay the eggs. (Coin, 2005; Libich, 2000; Williams, 2006)

How long do they live?

Goldsmith beetles develop for 1 to 2 years, and often hibernate for 4 to 6 months. This means that they live about 16 to 30 months in total. (Breda, 2001; Coin, 2005; Lockwood, 1868)

How do they behave?

Goldsmith beetles live the first 1 to 2 years of their life underground as larvae while they develop. Larvae burrow through the soil around tree roots. They make large round burrows that allow them to move around a lot. While resting in burrows, they curl up on their side to protect their soft parts. Very young larvae can't move very much, but they can crawl on their bellies. As they get bigger, they can move forward by laying on their back and moving back and forth like a snake. After they become adults, they live life in the trees. They fly between trees eating. They are most active from twilight to dawn. In the daytime, they make themselves a little shaded tent of leaves that they hold together. At night, they fly around bright lights like at gas stations. Goldsmith beetles usually hibernate in the soil at about 38 cm deep. Larvae burrow down deeper in the ground. (Coin, 2005; Lockwood, 1868; McColloch, et al., 1928)

Home Range

Scientists don't know the home range of goldsmith beetles. Adults probably have a larger home range because they can fly. (Coin, 2005; Milne and Milne, 1980; Williams, 2006)

How do they communicate with each other?

Like many of their close relatives, goldsmith beetles communicate by making noises with their legs. They move a ridged part of their body across thin ribs. They may use the sounds for mating or a different reason. In other similar beetles, these kind of sounds are used for courting, aggression, and defense. (Wessel, 2006)

What do they eat?

Goldsmith beetle larvae eat tree roots and rotting logs. Adults eat leaves of willow, pear, hickory, oak, and poplar trees. Goldsmith beetles usually feed at night. (Lockwood, 1868; Milne and Milne, 1980)

  • Plant Foods
  • leaves
  • roots and tubers
  • wood, bark, or stems

What eats them and how do they avoid being eaten?

Goldsmith beetles are eaten by birds that live in trees and eat insects. They are eaten by blue jays, yellow-billed cuckoos, and purple martins. Goldsmith beetles hide from predators in the tents they make to give them shade. This provides shade as well as cover from predators. Their bright gold color is probably a warning to predators, but scientists don't know if it's effective. (Judd, 1899; Lockwood, 1868)

  • These animal colors help protect them
  • aposematic

What roles do they have in the ecosystem?

Adult goldsmith beetles pull leaves from the trees where they live, which are usually willow and poplar trees. They are eaten by many birds that eat insects and live in trees. Goldsmith beetle larvae add air into the soil when they burrow and help dead logs decay. Goldsmith beetles and their close relatives get infected by sporeforming bacteria and milky disease bacteria. (Coin, 2005; Klein and Jackson, 1992; Lockwood, 1868; Williams, 2006)

Commensal or parasitic species (or larger taxonomic groups) that use this species as a host
  • spore-forming bacteria (Clostridium)
  • milky disease bacteria (Bacillus popilliae)

Do they cause problems?

Goldsmith beetles are possibly a nuisance to farmers and gardeners because they pull leaves from trees, but most of the time they live in trees. They are often confused with Japanese beetles, which can cause a lot of damage to soybean and corn crops. (Johnson, 1999)

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

How do they interact with us?

Goldsmith beetles help their ecosystem by adding air into the soil and breaking down rotting logs.

Are they endangered?

Goldsmith beetles are uncommon, but they are not endangered or threatened. (Coin, 2005)

Some more information...

Goldsmith beetles are in the short story "The Gold Bug" by Edgar Allan Poe. (Breda, 2001)


Charles Park (author), Rutgers University, Asha Parmar (author), Rutgers University, Lauren Seyler (author), Rutgers University, Hetal Shah (author), Rutgers University, David V. Howe (editor), Rutgers University, Gail McCormick (editor), Animal Diversity Web Staff, Catherine Kent (editor), Special Projects.


Breda, J. 2001. "Cotalpa lanigera" (On-line). Accessed December 14, 2006 at

Coin, P. 2005. "Species Cotalpa lanigera - Goldsmith Beetle" (On-line). BugGuide. Accessed December 09, 2006 at

Johnson, D. 1999. "Japanese Beetle in Soybean" (On-line). Accessed December 09, 2006 at

Judd, S. 1899. The Efficiency of Some Protective Adaptations in Securing Insects from Birds. The American Naturalist, 33(390): 461-484.

Klein, M., T. Jackson. 1992. Bacterial Diseases of Scarabs. Pp. 43-62 in T Glare, T Jackson, eds. Use of Pathogens in Scarab Pest Management. Hampshire: Intercept Limited.

Libich, T. 2000. "Beetles" (On-line). Accessed December 13, 2006 at

Lockwood, S. 1868. The Goldsmith Beetle and its Habits. The American Naturalist, 2(4): 186-192.

McColloch, J., W. Hayes, H. Bryson. 1928. Hibernation of Certain Scarabaeids and their Tiphia Parasites. Ecology, 9(1): 34-42.

Milne, L., M. Milne. 1980. National Audubon Society Field Guide to Insects and Spiders. New York: Knopf.

Wessel, A. 2006. Stridulation in the Coleoptera - An Overview. Pp. 397-403 in S Drosopoulos, M Claridge, eds. Insect Sounds and Communication: Physiology, Behavior, Ecology and Evolution. Boca Raton: Taylor and Francis Group.

Williams, L. 2006. "Northeast Region Forest Pest Update - 06/14/06" (On-line pdf). Wisconsin Department of Natural Resources. Accessed December 09, 2006 at

University of Michigan Museum of ZoologyNational Science Foundation

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Park, C.; A. Parmar; L. Seyler and H. Shah 2012. "Cotalpa lanigera" (On-line), Animal Diversity Web. Accessed May 20, 2024 at

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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