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Cotalpa lanigeragoldsmith beetle

By Charles Park; Asha Parmar; Lauren Seyler; Hetal Shah

Geographic Range

Goldsmith beetles, Cotalpa lanigera, are found in the eastern, central, and southwestern United States as well as southeastern Canada. (Coin, 2005)

Habitat

Goldsmith beetles inhabit deciduous forests, woodlands, and fields near those woodlands. (Coin, 2005)

Physical Description

Goldsmith beetles are yellow or green in color and have a gold, metallic tint. Their elytra has irregular rows of small holes, but they do not have elytral markings. Goldsmith beetles are egg-shaped and are relatively heavy and large, ranging from 20 to 26 mm in length. Their ventral side is covered with dense, whitish wool-like hairs. (Coin, 2005; Lockwood, 1868; Coin, 2005; Lockwood, 1868)

  • Range length
    20 to 26 mm
    0.79 to 1.02 in

Development

Like most beetles, goldsmith beetles are endopterygotes that completely metamorphose. Once eggs hatch, larvae burrow to reach a food source and tend to feed voraciously; the larval stage is the principal feeding stage of the life cycle of goldsmith beetles. Larvae, which are whitish and C-shaped, are called grubs and are have limited motion. After 1 or 2 years, larvae pupate, and a fully formed beetle emerges from a pupa. (Libich, 2000; Williams, 2006)

Reproduction

Specific mating systems have not been identified in goldsmith beetles. In most beetles, the sense of smell is thought to play a considerable role in the finding of a mate. Pairing is generally short but in some cases can last for several hours. During sexual pairing, sperm cells are transferred to the female to fertilize eggs. (Libich, 2000)

Goldsmith beetles breed between April and July. After a gestation period of about 6 months, females lay their eggs in clumps on top of the soil below a tree. They lay a small number of eggs relative to similar species. After a larval stage of 1 to 2 years, larvae enter a pupal stage. Adults emerge 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 below a tree near tree roots or rotting logs, potential food sources. Neither males nor females, however, are directly involved with parental care of their young after eggs are laid. (Coin, 2005; Libich, 2000; Williams, 2006)

Lifespan/Longevity

The lifespan of goldsmith beetles is not well documented. However, development takes 1 to 2 years, and they often hibernate for 4 to 6 months. Based on developmental times, goldsmith beetles may live at least 16 to 30 months. (Breda, 2001; Coin, 2005; Lockwood, 1868)

Behavior

Goldsmith beetles spend the first 1 to 2 years of their life underground as developing larvae. Larvae burrow through the soil surrounding the roots of trees, forming large round burrows that permit a great range of movement. When resting in burrows, they lie on the side of their body and curl up, protecting their delicate abdomens. Very young larvae are capable of limited movement that involves crawling on their ventral side. As larvae grow older and larger, they are able to move rapidly forward while lying on their dorsal side, legs facing upward, by making a serpentine motion. After pupation, they emerge from the soil as adults and begin an arboreal lifestyle, flying from tree to tree to feed. They are most active from twilight to dawn. During the day, they rest in the shade of leaves drawn together and held by their tarsi, forming an improvised tent. Adults are often seen at night flying around bright lights like those at gas stations. Adults usually hibernate during the winter, remaining about 38 cm below the soil surface. Larvae are usually found at greater depths. (Coin, 2005; Lockwood, 1868; McColloch, et al., 1928)

Home Range

The home range of goldsmith beetles has not yet been determined. Adults have a greater potential range because of their flight capabilities. (Coin, 2005; Milne and Milne, 1980; Williams, 2006)

Communication and Perception

Members of the subfamily Rutelinae, including goldsmith beetles, use stridulating organs on their legs to communicate. Sounds are produced by a plectrum, a sharply confined ridge, moving across femoral pars stridens that have fine parallel ribs, much like a rasp. It is uncertain whether these sounds are produced as a component of mating behavior or if they have some other purpose. In several taxa, including the superfamily Scarabaeoidea, these stridulating structures may produce several different sounds that serve varying functions, such as courtship, aggression, and defense. (Wessel, 2006)

Food Habits

As larvae, goldsmith beetles feed on tree roots and rotting logs around which they burrow. Adults feed on willow (Salix), pear (Pyrus), hickory (Carya), oak (Quercus), and poplar (Populus) foliage. They generally feed at night. (Lockwood, 1868; Milne and Milne, 1980)

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

Predation

Goldsmith beetles are preyed upon by arboreal, insectivorous birds, including blue jays, yellow-billed cuckoo, and purple martins. Adult goldsmith beetles form tents by folding surrounding tree leaves around their bodies and holding them in place with their telsi. This provides shade as well as cover from predators. Their bright metallic color is also thought to be a form of warning coloration, though its effectiveness is unknown. (Judd, 1899; Lockwood, 1868)

Ecosystem Roles

Adult goldsmith beetles strip foliage from the trees in which they take up residence, most commonly willow (Salix) and poplars (Populus). They are also a source of food for many arboreal, insectivorous birds. Larvae help aerate the soil and play an important role in the decaying process of dead logs. Members of the subfamily Rutelinae, including goldsmith beetles, also act as hosts to sporeforming bacteria such as Clostridium as well as milky disease bacteria (Bacillus popilliae). (Coin, 2005; Klein and Jackson, 1992; Lockwood, 1868; Williams, 2006)

Commensal/Parasitic Species
  • spore-forming bacteria (Clostridium)
  • milky disease bacteria (Bacillus popilliae)

Economic Importance for Humans: Positive

There are no known direct positive effects of goldsmith beetles on humans. Because they help aerate soil, break down rotting logs, and act as prey to a variety of birds, they help maintain a thriving ecosystem.

Economic Importance for Humans: Negative

Because adult goldsmith beetles are quite effective at stripping foliage from trees, they are potential nuisances to some farmers and gardeners. However, members of this species tend to remain in forested areas. They are often confused with far more destructive Japanese beetles, which are capable of causing a great amount of damage to soybean and corn crops. (Johnson, 1999)

  • Negative Impacts
  • crop pest

Conservation Status

Goldsmith beetles are usually considered uncommon, but have no special conservation status. (Coin, 2005)

Other Comments

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

Contributors

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.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

acoustic

uses sound to communicate

aposematic

having coloration that serves a protective function for the animal, usually used to refer to animals with colors that warn predators of their toxicity. For example: animals with bright red or yellow coloration are often toxic or distasteful.

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

crepuscular

active at dawn and dusk

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

female parental care

parental care is carried out by females

folivore

an animal that mainly eats leaves.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

fossorial

Referring to a burrowing life-style or behavior, specialized for digging or burrowing.

herbivore

An animal that eats mainly plants or parts of plants.

hibernation

the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

soil aeration

digs and breaks up soil so air and water can get in

solitary

lives alone

tactile

uses touch to communicate

terrestrial

Living on the ground.

vibrations

movements of a hard surface that are produced by animals as signals to others

visual

uses sight to communicate

References

Breda, J. 2001. "Cotalpa lanigera" (On-line). Accessed December 14, 2006 at http://entweb.clemson.edu/museum/beetles/local/btle28.htm.

Coin, P. 2005. "Species Cotalpa lanigera - Goldsmith Beetle" (On-line). BugGuide. Accessed December 09, 2006 at http://bugguide.net/node/view/4293.

Johnson, D. 1999. "Japanese Beetle in Soybean" (On-line). Accessed December 09, 2006 at http://www.uky.edu/Ag/kpn/kpn_99/pn990628.htm.

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 http://www.goliathus.com/en/beetles.php.

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 http://prodwbin99.dnr.state.wi.us/org/land/Forestry/Fh/PDF/NER-pestsupdate-2006-6-14.pdf.

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