Sciaridae

Sciaridae
Sciara hemerobioides
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Diptera
Suborder:	Nematocera
Infraorder:	Bibionomorpha
Superfamily:	Sciaroidea
Family:	Sciaridae
Genera
Bradysia Winnertz, 1867 Bradysiopsis Tuomikoski, 1960 Camptochaeta Hippa & Vilkamaa, 1994 Claustropyga Hippa, Vilkamaa & Mohrig, 2003 Corynoptera Winnertz, 1867 Cratyna Winnertz, 1867 Ctenosciara Tuomikoski, 1960 Epidapus Haliday in Walker, 1851 Leptosciarella Tuomikoski, 1960 Lycoriella Frey, 1942 Phytosciara Frey, 1942 Pnyxia Johannsen, 1912 Pseudolycoriella Menzel & Mohrig, 1998 Scatopsciara Edwards, 1927 Schwenckfeldina Frey, 1942 Sciara Meigen, 1803 Scythropochroa Enderlein, 1911 Trichosia Winnertz, 1867 Xylosciara Tuomikoski, 1957 Zygoneura Meigen, 1830 Many others

Sciaridae is a family of flies, commonly known as dark-winged fungus gnats. Commonly found in moist environments, they are known to be a pest of mushroom farms and are commonly found in household plant pots. This is one of the least studied of the large Diptera families, probably due to the small size of these insects and the difficulty in specific identification. There are currently around 1700 described species but there are estimated to be up to 20,000 species awaiting discovery, mainly in the tropics. More than 600 species are known from Europe.

Description

These gnats are small, from one to at the very most seven millimetres long. They have a slender, darkly colored body and dark wings. However, the females of several species are wingless. Their long legs and antennae with 8 to 16 segments are typical of many gnats.

Family Description (formal)

See [1] and images at Diptera.info

The slender whitish larvae feature a sclerotized head capsule.

Distribution

The Sciaridae occur worldwide, even in extreme habitats like antarctic islands and mountainous regions above 4,000 metres. Others (like Parapnyxia) are found in deserts, where they dig into the sand at extreme temperatures. Several species live exclusively in caves. However, most species live in forests, swamps, and moist meadows, where they live in the foliage. They are also often found in flowerpots. In moist and shadowy areas up to 70% of all diptera species can be Sciaridae.

They are distributed through wind and drifting, for example on dead wood, and are often introduced by humans, by means of transported humus or similar.

Species lists

• Palaearctic
• Nearctic
• Australasian/Oceanian
• Japan

Life cycle

The life cycle of only a few species has been studied in any detail, mainly those which are pests of commercially grown mushrooms. Sciarid larvae are mainly found in soil and plant litter where they seem to feed mainly on fungi and animal faeces. There are also species that mine in plant parts above and below the earth. The larvae play an important role in turning forest leaf litter into soil.

Adult females lay about 200 transparent eggs (each about one millimeter long) into moist soil. After about one week the larvae hatch. 90% of larvae are female. Up to 2,500 per m² can be found. Several species, especially Sciara militaris, can be found to migrate in processions of up to ten meters, containing thousands of individuals. These processions occur from May to June in central Europe. The larvae there pupate from July to August.

The adults with their characteristical dancing flight do not sting. They only ingest liquids and live only long enough to mate and produce eggs. They die after about five days.

The use of cedar wood chips^[1] is one way to keep Sciaridae away from plants.

Mating and genetics

The Sciaridae practice paternal genome elimination, whereby the male passes on only the genetic material of his mother to his offspring. The functional result of this is similar to haplodiploidy, but via a very different mechanism.

Evolution

Sciarids are fairly common in amber deposits, the earliest known fossils dating from the Cretaceous period.

Sciarid fly in amber

See also

• Lasthenia conjugens

References

1. ^ "Windowsill Cactus: Growing Cactus Plants from Seeds". windowsillcactus.com. http://windowsillcactus.com/growing_cactus_plants_from_seeds_information.shtml#preventing_fungus_gnats. Retrieved 2008-04-14. 

• Expert website (Frank Menzel)
• Taxonomy and phylogeny of Sciaridae
• Family description
• Fossil Diptera catalog
• This page incorporates information from the German Wikipedia.

External links

• Fungus Gnats Online
• Bradysia spp., darkwinged fungus gnats on the UF / IFAS Featured Creatures Web site
• Diptera.info Gallery Images