Animal Fact Sheets

darkling beetle range map

DARKLING BEETLE

(Eleodes spp.)
 

Classification and Range

Darkling beetles are in the class Insecta, order Coleoptera and family Tenebrionidae. Darkling beetles represent what most people would consider the typical beetle. There are approximately 1,400 species of darkling beetles in North America. Most live in the western United States, including about 100 species of the genus Eleodes. Only about 150 species of darkling beetles occur in the eastern United States.

Habitat

Darkling beetles are common in many habitats, but are especially adapted to arid regions.

Physical Characteristics

Darkling beetles are approximately 1.5 inches (3.8 cm) in length. They have chewing mouthparts and one pair of antennae. The antennae are often segmented into 11 parts and are thread-like, bead-like or slightly cubed. The darkling beetle does not have any major distinguishing characteristics. There are no bumps or outgrowths, as they are uniformly smooth and black; one end is easy to tell from the other. Wings of the darkling beetle are fused, rendering this beetle flightless.

Life Span

Darkling beetles can live from 3-15 years.

Diet

IIn the wild: Darkling beetles commonly eat decaying vegetation, such as dead leaves or rotting wood
At the zoo: Apples, oranges, romaine lettuce and monkey chow

Reproduction

The female lays her eggs in the soil. When larvae hatch, they look similar to commercial mealworms (genus Tenebrio). Larvae have six legs, and are slender, cylindrical, light brown and worm-like in appearance. When larvae reach the proper size, they pupate in the soil. They emerge as adult darkling beetles.

Life Cycle

Both larvae and adults are general feeders and scavengers, feeding on decaying fungi, leaves, seeds and other organic matter. They occasionally eat live plants. Darkling beetles are ground dwellers. They are active both day and night, but spend the hottest part of the day in moist areas, such as the undersides of logs and rocks, in fungi, and in other cool, dark places.

Rear Assault!

Members of the genus Eleodes have perfected an interesting defense against predators, which include birds, reptiles and amphibians. When threatened, a beetle stands on its head and elevates its rear end. When the aggressor gets within striking distance, the beetle emits a foul-smelling black fluid, driving away its adversary. This is why darkling beetles belonging to the genus Eleodes, have the nickname "stink" beetles.

Location at the Zoo

Incredible darkling beetles are located at Woodland Park Zoo's Bug World. You'll go "buggy" while viewing exciting seasonal displays that take you on a journey to different bioclimatic zones around the world. You may come face-to-face with recycling cockroaches, assassin bugs, web-spinning spiders or scuba diving beetles, to name only a few. The only way you'll find out which bugs you'll encounter is by visiting Bug World. Don't miss it!

Conservation Connection

Darkling beetles are common throughout the world. Human-caused changes in land use are escalating, and this affects the natural habitat required by darkling beetles and other animals for survival. Vast forests are being removed for timber or other paper products, and industrial emissions are polluting water and air resources. Additionally, habitat is rapidly converted by expanding human communities and agricultural needs. It's only a matter of time until many insect species populations will become severely reduced, or eliminated.

Humans need insects. Often unnoticed, darkling beetles and other insects are essential for maintaining the balance in nature and health of the living world. Here are only a few of the benefits insects provide:

  • Bees, butterflies and other insects pollinate wild plants and our crops, ensuring the production of seeds and fruits required for the continued survival of plants and animals.
  • Earwigs, beetles and other insect scavengers clean up the environment by consuming decaying plants and animals. Nutrients are recycled back into the soil, helping future generations of plants to grow.
  • Many species of carnivorous beetles, ants and wasps eat other harmful insects that damage or destroy our crops and spread disease.
  • Burrowing insects aerate and enrich the soil.
  • Insects are a source of food for animals, including humans!
  • Insects produce products used by people, including honey, beeswax, silk and dyes, to name only a few.

 

How You Can Help!

The effort to save animals and their habitat requires cooperation and support at the international, national, regional and individual levels. You can help in this cause. Join and become active in Woodland Park Zoo and other conservation organizations of your choice. To conserve habitat for beetles and other insects, reduce your use of pesticides and herbicides, and work to preserve vegetation in your neighborhood and in tropical regions.

Contact Woodland Park Zoo at webkeeper@zoo.org to find out how you can support conservation efforts at the zoo. Learn other ways you can help conserve wildlife and the habitats they require for survival by visiting our How You Can Help page.

 

Darkling Beetle Fascinating Facts

  • Darkling beetles do not need to drink water—they extract water from their food. Their fused wings also prevent water loss!
  • Approximately 290,000 species of beetles have been identified to date. That is nearly one-third of all insects which have been named!
  • All beetles go through complete metamorphosis where during the pupal stage, larvae rapidly change to adult form!
  • Measuring up to 6 inches (15 cm), the Goliath beetle is the largest beetle in the world!

Sources and Suggested Reading

Borror, Donald Joyce. 1974. A Field Guide to Insects: America North of Mexico (Petersen Field Guide Series). Houghton Mifflin Company, Boston, MA. 404 p.

Evans, Arthur V. and Charles L. Bellamy. 1996. An Indordinate Fondness for Beetles. Henry Holt and Company, Inc., New York, NY. 208 p.

Nuridsany, Claude and Marie Perennou. 1997. Microcosmos. Stewart, Tabori & Chang, New York, NY. 160 p.

For Kids!

Gaffrey, Michael. 1994. Secret Forest. Golden Book, Western Publishing Company, Inc., Racine, WI. 31 p.

Mound, Laurence. 1990. Insect (Eyewitness Book). Alfred A. Knopf, Inc., New York, NY. 64 p.

Zoobooks. 1994. Insects. Wildlife Education Ltd., San Diego, CA. 18 p.

 
 
 
 

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