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Carpet, Flesh-Eating, and Trilobite Beetles: Strange Insects
Interesting and Successful Insects
Beetles are fascinating and abundant insects. The group contains some strange members, including carpet, flesh-eating, and trilobite beetles. The larvae of varied carpet beetles feed on natural fibers and can destroy carpets, clothing, and furniture coverings. Museums use flesh-eating beetles to strip the flesh off animal bones so that the bones can be displayed. The insects are also useful in forensic science. Female trilobite beetles have a flattened body that is covered by segmented plates and reminds researchers of the ancient trilobites that once roamed the oceans.
Beetles are very successful insects. One reason for this success is thought to be their wing structure. Most beetles (but not trilobite beetles) have a pair of thick and tough forewings called elytra on the surface of their bodies. When the beetles take off for flight, they raise the elytra out of the way to reveal the more delicate and membranous hindwings underneath, which are used for flying. The elytra help to protect the hindwings from injury as the beetles move over land.
The order Coleoptera contains different families. Carpet and flesh-eating beetles are classified in the family Dermestidae and are sometimes known as dermestid beetles. Trilobite beetles belong to the family Lycidae.
The Varied Carpet Beetle
The varied carpet beetle (Anthrenus verbasci) is an attractive insect in both its adult and its larval form. It has a widespread range and is found in many countries. The larva can be an extremely annoying and destructive pest in homes.
Varied carpet beetle adults have a blotched brown, orange, yellow, and white appearance and are covered with scales. They feed on pollen and aren't pests. They are short-lived compared to the larvae, however. A larva is covered with brown hair-like structures called setae and looks furry. It's often called a "woolly bear". (This term is also used for the larvae of some other insects, such as the caterpillar of certain moths.)
The larvae of varied carpet beetles live between one and three years. This could be bad news, since they feed on many different things in our homes. They eat the natural fibers in our carpets, clothing, upholstery, and tapestries. They also eat animal hair and skins, leather, feathers, silk, horn, dead insects, other dead animals, dried meat, and pet food. They eat some plant material as well, including ground grains, cereals, and spices.
The Living Insect
Although many beetles are black in color, some are beautiful. Metallic and iridescent sheens, attractive colors, and interesting patterns produce a lovely appearance.
How to Get Rid of Carpet Beetles
Pest experts say that one of the best ways to prevent or get rid of a carpet beetle infestation is to follow good housekeeping practices. It’s important to vacuum carpets and areas where the beetles hide, such as shelves, baseboards, corners, and cracks. Other places that need to kept clean are the area behind radiators, the spaces inside heating ducts and furniture, and the edges of carpets. It's essential to get right to the back of a crevice with a vacuum cleaner when fighting an infestation. The bag of the vacuum cleaner needs to be discarded after use.
Infested clothing needs to be thoroughly cleaned or thrown away. Heating infested items in a hot dryer for an hour or more or cooling them in a freezer for several days can kill the beetles, according to pest controllers. Once it’s certain that clothing contains no beetles, it should be stored in a sealed chest or in carefully sealed plastic bags.
A serious carpet beetle infestation may need professional help. The beetles sometimes hide in nearby wasp and bird nests as well as homes, so it's important to watch for new infestations once one has been eliminated.
Flesh-Eating Beetles in Museums
The species of beetle that is most often used to clean skeletons is Dermestes maculatus. This species is sometimes called the hide beetle. It's native to Canada, continental USA, and Hawaii but is also found in Europe and Asia.
When museums have a mammal or bird body which they would like to "skeletonize" for display, they sometimes place their flesh-eating beetle colony in contact with the body. Both the adults and the larvae eat flesh, but the larvae do most of the work in cleaning bones. The beetles may be used in preference to a chemical method of removing flesh, which can damage the bones.
Flesh-eating beetles have to be used with care. Like carpet beetles, they will eat fibers from living things, including paper fibers. They must be kept away from books, wood, carpets, and stuffed animals in museums.
Dermestids (Adults and Larvae) Cleaning a Rabbit Skull
Other Uses of the Insects
Wildlife Law Enforcement
The United States Fish and Wildlife Service operates a forensic laboratory. The lab uses beetles to skeletonize partial or damaged animal remains in order to positively identify the specimens. This can be useful in investigations related to wildlife law enforcement.
Flesh-eating beetles are also helpful in forensic science, which is used to investigate crimes. The presence of the beetles on or in a dead body can be used to estimate the time of a person's death, for example. The presence of adults, larvae, and the beetle's feces provide significant clues for a knowledgeable person. The recent daily temperatures where the body was found are important, since the time needed for the beetle to complete its life cycle is different at different temperatures.
Home and School Use
Flesh-eating beetles are offered for sale to the public as “Dermestid Beetles”. People use them to clean the skeletons of dead animals. If the beetles are kept in a home or school, though, they must be contained or kept under control to prevent problems. If they can't find animal flesh they will feed on other material if they can get to it.
A Trilobite Beetle in Laos
Trilobite beetles are strange but little-known insects that have been found in the tropical rainforests of Southeast Asia and India. They belong to the family Lycidae and the genus Platerodrilus (or Duliticola in an older naming system).
A female trilobite beetle looks very different from other beetles. Her body is flattened and is divided into segments that look like plates of armour. The plates are decorated with knobs and projections. The head is tiny in relation to the size of the plates and is retractable. The beetle’s appearance reminded early observers of extinct marine animals called trilobites. Some of the females that have been discovered are colorful and beautiful insects.
Male trilobite beetles appear to be much smaller than the females and seem to have a typical beetle appearance. The fact that the genders are so different in both appearance and size makes it hard for researchers to recognize that they belong to the same species.
In many insects, the egg hatches into a larva. There may be several larval stages. The final stage changes into a pupa, from which the adult emerges. The adult has a very different appearance from the larvae. Female trilobite beetles stay in the larviform phase their whole lives (although they do molt and grow bigger), a phenomenon known as neoteny.
A Glowing Insect
The Life of a Trilobite Beetle
Trilobite beetles are thought to feed on microbes in the plant liquids obtained from rotting wood. This is by no means certain, however. They may survive on fungi and slime molds. They may even be predators and hunt for prey, which may include other insects and snails. The beetles don't have wings and explore their environment by walking.
Some trilobite beetles are bioluminescent, which means that they can produce light inside their bodies. In other bioluminescent beetles, the light is produced when an enzyme breaks down a chemical called luciferin, producing energy as light. This may be the method by which trilobite beetles produce light, too. Other beetles use bioluminescence to attract prey or mates or to warn would-be predators that the beetle tastes bad.
A Bioluminescent Trilobite Beetle in Thailand
The Importance of Research
Beetles are intriguing insects and are interesting animals to study. Many affect our lives, sometimes significantly, so understanding their anatomy, physiology, and behavior is important. It's also important that we know how to support the lives and reproduction of useful species and how to control the harmful ones.
There are almost certainly many more species of beetles still to be discovered on Earth. Perhaps some of them will be as strange as—or even stranger than—the carpet, flesh-eating, and trilobite beetles.
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© 2011 Linda Crampton