Long-horned Beetles, Family Cerambycidae

Habits and Traits of Long-Horned Beetles

Elderberry borer, a long-horned beetle.
The elderberry borer is one of the more brightly colored long-horned beetles. Wikimedia Commons/ Quer0zen CC BY-SA 3.0

With well over 30,000 species worldwide, the long-horned beetle family is one of the most diverse and important groups of insects on the planet. The family name, Cerambycidae, is believed to derive from the Greek kerambyx, meaning a horned beetle (which itself derives from the Greek keras, meaning horn).

Description:

Although they're called long-horned beetles, Cerambycids don't have horns like their rhinoceros beetle cousins.

The horns in question are actually their long antennae, which extend at least half the length of the beetle's body (and in some cases, are longer than its body). Their compound eyes are usually notched and wrapped around the base of the antennae. A key trait for the identification of long-horned beetles is their five-segmented tarsi, but this can be difficult to see because the small fourth segment is usually hidden.

In general, long-horned beetles tend to be elongate in shape, though they vary greatly in size from just a few millimeters to 150 mm long. North American species fall in the smaller end of this size range, rarely exceeding 60 millimeters in length. Nocturnal long-horned beetles are usually dark in color, while the day-flying species are often brightly marked and colored, like the flowers they visit.

Long-horned beetle larvae are rather nondescript ­– white or pale, elongate and cylindrical, and essentially legless.

They bore into wood, making circular tunnels (in contrast to the oval tunnels made by boring jewel beetle larvae). Some long-horned beetles cause galls to form on their host plants.

While long-horned beetles perform a vital ecosystem function as recyclers of wood, their feeding habits can be destructive to ornamental and shade trees, especially those that are stressed or injured.

And when a long-horned beetle invades a new habitat, it can be a serious threat to native trees. The Asian longhorned beetle (ALB), an exotic species that was first detected in North America in the early 1990's, has caused the destruction of thousands of trees in the eastern U.S.

Classification:

Kingdom – Animalia
Phylum – Arthropoda
Class – Insecta
Order – Coleoptera
Family - Cerambycidae

Diet:

Long-horned beetles are phytophagous, although they vary greatly in their feeding habits. Most long-horned beetle larvae feed in dead or decaying wood, and are therefore important decomposers of wood. It is believed that special enzymes enable the larvae to digest the tough cellulose fibers of the wood. Some feed on plant roots in the soil, and others feed on living plant tissues.

Some adult long-horned beetles visit flowers, and consume nectar and pollen. Within this large beetle family, there are species that feed on everything from sap to fungi.

Life Cycle:

Like all beetles, long-horned beetles undergo complete metamorphosis with four stages: egg, larva, pupa, and adult. Adult long-horned beetles deposit eggs in the crevices of bark on the host tree. When the larvae hatch, they bore into the wood (they are sometimes referred to as round-headed wood borers during this stage).

In temperate regions, the life cycle may last up to 3 years, with most of that time spent in the larval stage. Long-horned beetle larvae pupate inside the host tree, and the adult emerges ready to reproduce soon after. Depending on the species, the adult stage may last only a few days, or as long as several months.

Special Behaviors and Defenses:

Some long-horned beetles stridulate when handled, and will produce an audible squeak in protest. Many species that visit flowers are black and yellow in mimicry of wasps.

Range and Distribution:

The Cerambycidae family is one of the ten largest beetle families, with well over 30,000 species known worldwide. About 1,000 species of long-horned beetles inhabit North America, and these are organized into over 300 genera.

Sources:

  • Borror and DeLong's Introduction to the Study of Insects, 7th edition, by Charles A. Triplehorn and Norman F. Johnson.
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Hadley, Debbie. "Long-horned Beetles, Family Cerambycidae." ThoughtCo, Sep. 28, 2015, thoughtco.com/jewel-beetles-family-buprestidae-p2-1968128. Hadley, Debbie. (2015, September 28). Long-horned Beetles, Family Cerambycidae. Retrieved from https://www.thoughtco.com/jewel-beetles-family-buprestidae-p2-1968128 Hadley, Debbie. "Long-horned Beetles, Family Cerambycidae." ThoughtCo. https://www.thoughtco.com/jewel-beetles-family-buprestidae-p2-1968128 (accessed December 11, 2017).