Symphylans, also known as garden centipedes or glasshouse symphylans, are soil-dwelling arthropods of the class Symphyla in the subphylum Myriapoda. Symphylans resemble centipedes, but are smaller and translucent. They can move rapidly through the pores between soil particles, and are typically found from the surface down to a depth of about 50 cm. They consume decaying vegetation, but can do considerable harm in an agricultural setting by consuming seeds, roots, and root hairs in cultivated soil.
Juveniles have six pairs of legs, but, over a lifetime of several years, add an additional pair at each moult so that the adult instar has twelve pairs of legs. Lacking eyes, their long antennae serve as sense organs. They have several features linking them to early insects, such as a labium (fused second maxillae), an identical number of head segments and certain features of their legs.
About 200 species are known worldwide.
The head has long, segmented antennae, a postantennal organ, three pairs of mouthparts: mandibles, the long first maxillae, and the second pair of maxillae which are fused to form the lower lip or labium of the mouth. Disc-like organs of Tömösvary, which probably sense vibrations, are attached to the base of the antennae, as they are in centipedes.
The trunk comprises 15–24 segments, which are protected by overlapping dorsal plates. Ten or twelve segments bear legs. The first segment is large and usually provided with a pair of legs, the last segment is slender, lacks legs, and possesses a pair of cerci. Immature individuals have six pairs of legs on hatching. Each pair of legs is associated with an eversible structure, called a "coxal sac", that helps the animal absorb moisture, and a small stylus that may be sensory in function. Similar structures are found in the most primitive insects.
Symphyla are rapid runners. They are primarily herbivores and detritus feeders living deep in the soil, under stones, in decaying wood, and in other moist places where they feed on the root hairs and rootlets and can sometimes cause crop failure. The garden centipede, Scutigerella immaculata can be a serious pest of vegetable crops and tree seedlings and occurs in greenhouses as well as agricultural situations. A species of Hanseniella has been recorded as a pest of sugar cane and pineapples in Queensland . A few species are found up trees  and in caves . A species of Symphylella has been shown to be predominantly predatory , and some species are saprophagous.
The genital openings are located on the fourth body segment, but the animals do not copulate. Instead, the male deposits 150 to 450 packages of sperm, or spermatophores, on small stalks. The female then picks these up in her mouth, which contains special pouches for storing the sperm. She then lays her eggs, and attaches them to the sides of crevices or to moss or lichen with her mouth, smearing the sperm over them as she does so. The eggs are laid in groups of 8 to 12.
- "Garden Symphylans". Integrated Pest Management on Peppermint-IPMP3.0. Oregon State University. Retrieved 2007-07-02.
- C. Gillott (2005). Entomology, 3rd Edition. Springer Verlag. ISBN 1-4020-3182-3.
- A. D. Chapman (2005). Numbers of Living Species in Australia and the World. Department of the Environment and Heritage. ISBN 0-642-56850-2.
- Penny Greenslade (2002-03-31). "Class: Symphyla". Australian Faunal Directory. Australian National University.
- Barnes, Robert D. (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. pp. 817–818. ISBN 0-03-056747-5.
- H. Boyle (1981). "Symphyla control in young plant cane". Cane Growers' Quarterly Bulletin 44: 115–116.
- D. A. H. Murray & D. Smith (1983). "Effect of Symphyla, Hanseniella sp., on establishment of pineappes in south-east Queensland". Queensland Journal of Agricultural Science 40: 121–123.
- J. Adis & U. Scheller (1984). "On the natural history and ecology of Hanseniella arborea (Myriapoda, Symphyla, Scutigerellidae), a migrating symphylan from an Amazonian black-water inundation forest". Pedobiologia 27: 35–41.
- S. Clark & P. Greenslade (1996). "Review of Tasmanian Hanseniella Bagnall (Symphyla: Scutigerellidae)". Invertebrate Taxonomy 10 (1): 189–212. doi:10.1071/IT9960189.
- Eberhard, S.M. & Spate (1995). "Cave Invertebrate Survey; toward an atlas of NSW Cave Fauna". A report prepared under NSW Heritage Assistance Program NEP 94: 765.
- D. E. Walter, J. C. Moore & S. Loring (1989). "Symphylella sp. (Symphyla: Scolopendrellidae predators of arthropods and nematodes in grassland soils". Pedobiologia 33: 113–116.
- The complete mitochondrial genome of Symphylella sp. (Myriapodaa: Symphyla): Extensive gene order rearrangement and evidence in favor of Progoneata.
Further reading 
- C. A. Edwards (1990). "Symphyla". In Daniel L. Dindal. Soil Biology Guide. New York: Wiley. pp. 891–910. ISBN 978-0-471-04551-9.
- U. Scheller (1961). "A review of the Australian Symphyla (Myriapoda)". Australian Journal of Zoology 9 (1): 140–171. doi:10.1071/ZO9610140.
- U. Scheller (1982). "Symphyla". In Sybil P. Parker. Synopsis and Classification of Living Organisms. New York: McGraw-Hill. pp. 688–689. ISBN 978-0-07-079031-5.
- R. J. Tillyard (1930). "The evolution of the class Insecta". Papers and Proceedings of the Royal Society of Tasmania 1930: 1–89.
- Data related to Symphyla at Wikispecies