Scutigera coleoptrata (one of several species commonly known as the house centipede), is a typically yellowish-grey centipede with up to 15 pairs of legs. Originating in the Mediterranean region, the species has spread to other parts of the world, where it usually lives in human homes. It is an insectivore; it kills and eats other arthropods, such as insects and arachnids.
S. coleoptrata is 25 mm (1 in) to 50 mm (2 in) in length and has up to 15 pairs of remarkably long legs. These delicate legs are attached to a rigid body. This enables it to reach surprising speeds of up to 0.4 meters per second (1.3 ft/s) running across floors, up walls and along ceilings. Its body is yellowish-grey and has three dark dorsal stripes running down its length; the legs also have dark stripes. Unlike most other centipedes, house centipedes and their close relatives have well-developed, faceted eyes. S. coleoptrata has developed automimicry in that its hind legs present the appearance of antennae. When the centipede is at rest, it is not easy to tell its front from its back.
Reproduction and development
House centipedes lay their eggs in spring. In a laboratory observation of 24 house centipedes, an average of 63 and a maximum of 151 eggs were laid. As with many other arthropods, the larvae look like miniature versions of the adult, albeit with fewer legs. Young centipedes have four pairs of legs when they are hatched. They gain a new pair with the first molting, and two pairs with each of their five subsequent moltings. Adults with 15 pairs of legs retain that number through three more molting stages (sequence 4-5-7-9-11-13-15-15-15-15 pairs). They live anywhere from three to seven years, depending on the environment. They can start breeding in their third year. To begin mating, the male and female circle around each other. They initiate contact with their antennae. The male deposits his sperm on the ground and the female then uses it to fertilize her eggs.
Behavior and ecology
House centipedes feed on spiders, bed bugs, termites, cockroaches, silverfish, ants, and other household arthropods. They administer venom through modified legs. These are not part of their mandibles, so strictly speaking they sting rather than bite. They are mostly nocturnal hunters. Despite their developed eyes they seem to rely mostly on their antennae when hunting. Their antennae are sensitive to both smells and tactile information. They use both their mandibles and their legs for holding prey. This way they can deal with several small insects at the same time. To capture prey they either jump onto it or use their legs in a technique described as "lassoing". Using their legs to beat prey has also been described. In a feeding study, S. coleoptrata showed the ability to distinguish between possible prey. They avoid dangerous insects. They also adapted their feeding pattern to the hazard the prey might pose to them. For wasps, they retreat after applying the venom to give it time to take effect. When the centipede is in danger of becoming prey itself, it can detach any legs that have become trapped. House centipedes have been observed to groom their legs by curling around and grooming them with their forcipules.
It may often be seen darting across floors with very great speed, occasionally stopping suddenly and remaining absolutely motionless, presently to resume its rapid movements, often darting directly at inmates of the house, particularly women, evidently with a desire to conceal itself beneath their dresses, and thus creating much consternation.
Outdoors, house centipedes prefer to live in cool, damp places. Centipede respiratory systems do not provide any mechanism for shutting the spiracles, and that is why they need an environment that protects them from dehydration and excessive cold. Most live outside, primarily under large rocks, piles of wood, and especially in compost piles. Within the home, these centipedes are found in almost any part of the house. Most commonly they are encountered in basements, bathrooms, and lavatories, which tend to be humid, but they can also be found in drier places like offices, bedrooms and dining rooms. The greatest likelihood of encountering them is in spring, when they come out because the weather gets warmer, and in autumn/fall, when the cooling weather forces them to find shelter in human habitats.
Scutigera coleoptrata is indigenous to the Mediterranean region, but it has spread through much of Europe, Asia, North America and South America. It is thought to have first been introduced to the Americas in Mexico and Guatemala and now it reaches north into Canada and south to Argentina.
In the United States, it spread north from the southern states, reaching Pennsylvania in 1849, New York in 1885, and Massachusetts and Connecticut in about 1890. In 2009, its distribution extended from Virginia in the east to the coast of California in the west. At the University of Illinois's Smith Hall, it has known to be called the "Smith Crawler" or "Smith Bug" by students attending the university.
In South Africa, they have been found in the Western Cape, in and around Cape Town (sightings have been reported in Pinelands, Vredehoek, Mowbray, Edgemead, Green Point, Cape Town, Zonnebloem, Cape Town, Woodstock, Cape Town and Gordon's Bay) and also in KwaZulu-Natal, in the city of Pietermaritzburg.
The faceted eyes of Scutigera coleoptrata are sensitive to daylight as well as very sensitive to ultraviolet light. They were shown to be able to visually distinguish between different mutations of Drosophila melanogaster. How this ability fits with its nocturnal lifestyle and underground natural habitat is still under study. They do not instantly change direction when light is suddenly shone at them, but retreat to a darker hiding spot.
Some of the plates covering the body segments fused and became smaller during the evolution to S. coleoptrata's current state. The resulting mismatch between body segments and dorsal plates (tergites) is the cause for this centipede's rigid body.
|Segments||1||2||3, 4||5, 6||7, 8, 9||10, 11||12, 13||14, 15||16||17||18|
|Leg pairs||Forcipules||1||2, 3||4, 5||6, 7, 8||9, 10||11, 12||13, 14||15 (antenna-like snare legs)||(gonopod)||(anus)|
Interaction with humans
Unlike its shorter-legged but much larger tropical cousins, Scutigera coleoptrata can live its entire life inside a building, usually the ground levels of homes. They are generally considered harmless to humans. Bites (stings) are extremely uncommon, and the forcipules of most house centipedes are not strong enough to penetrate human skin. Stings are generally no worse than a bee's sting, with its venom causing redness and mild to severe swelling.
Techniques for eliminating centipedes from homes include drying up the areas where they thrive, eliminating large indoor insect populations, sealing cracks in the walls, and seeking the assistance of an exterminator.
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- Victor Benno Meyer-Rochow, Carsten H. G. Müller & Magnus Lindström (2006). "Spectral sensitivity of the eye of Scutigera coleoptrata (Linnaeus, 1758) (Chilopoda: Scutigeromorpha: Scutigeridae)". Applied Entomology and Zoology 41 (1): 117–122. doi:10.1303/aez.2006.117.
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- Enrico Negrisolo, Alessandro Minelli & Giorgio Valle (2004). "The mitochondrial genome of the house centipede Scutigera and the monophyly versus paraphyly of myriapods". Molecular Biology and Evolution 21 (4): 770–780. doi:10.1093/molbev/msh078. PMID 14963096. http://mbe.oxfordjournals.org/cgi/content/full/21/4/770.
- Eric R. Eaton (2007). Kaufman Field Guide to Insects of North America. HMCo Field Guides. p. 26. ISBN 0-618-15310-1. http://books.google.com/books?id=aWVi0IF_jcQC&lpg=PA50&dq=House%20Centipede%20&pg=PA26. Retrieved July 3, 2009.
- Jeffrey K. Barnes (2003). "House Centipede". http://www.uark.edu/ua/arthmuse//house_centipede.html.
- Steve Jacobs (2006). "House Centipedes". http://ento.psu.edu/extension/factsheets/house-centipedes.