ThePiophilidae are afamily of "true flies", in theorderDiptera. The so-calledcheese flies are the best-known members, but most species of the Piophilidae are scavengers in animal products,carrion, and fungi. They may accordingly be important inforensic entomology^[1] andmedical entomology.^[2] For a fly maggot, the larvae of many species have an unusually well-developed ability to leap when alarmed or when abandoning their larval food to pupate; they accordingly may be known ascheese skippers or other kinds of skippers according to their food source.^[3]

Cheese flies
Piophila casei
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Diptera
Superfamily:	Tephritoidea
Family:	Piophilidae Macquart, 1835
Subfamilies
Neottiophilinae Piophilinae Thyreophorinae
Synonyms
Neottiophilidae Thyreophoridae

The most notorious member of the family is thecheese fly,Piophila casei; it iscosmopolitan, and a typical member of the family. It is a small species, about 4 mm (0.16 in) long. The fly'slarvae infest cured meats, smoked or salted fish, cheeses, andcarrion. The mature larva is about 8 mm (0.31 in) long and is sometimes called the cheese skipper because of its leaping ability - when disturbed, this tiny maggot can hop some 15 cm (6 in) into the air.^[4] Adults are also known as bacon flies and their larvae as bacon skippers, ham skippers, cheese maggots, cheese hoppers, etc. In theMediterranean island ofSardinia, the larvae are intentionally introduced intopecorinocheese to produce the characteristiccasu marzu ("rotten cheese" inSardinian).

The adult cheese fly's body is black, blue-black, or bronze, with some yellow on the head, antennae, and legs. The wings are faintlyiridescent and lie flat upon the fly'sabdomen when at rest. At 4 mm (0.16 in) long, the fly is one-third to one-half as long as the commonhousefly.

Like the larvae of various fly families, including the familyTephritidae, the larvae of typical piophilids are notorious for jumping or "skipping", especially in their finalinstar.^[5][6] The larvae accomplish their jumps by bending over, grabbing onto the rears of their own bodies with their mouth hooks, and tensing their muscles in a manner that increases the pressure on their own blood and internal organs. When they release their grip, the internal pressure straightens out the tubular body, propelling the forequarters upwards, the rest of the body following.^[4] Jumping is performed most typically when the larva is alarmed by a disturbance, or when it is abandoning its feeding site in preparation for pupation.

The tiny piophilid speciesProtopiophila litigata, commonly known as the antler fly,^[7] breeds on discarded antlers of moose and other deer. On discarded antlers, the males form complex, highly structuredaggregations in which a great deal ofterritorial competition occurs. In prime areas of the antler, near oviposition sites (cracks in the antler surface), males spend much of their time battling rival males. Males spend their entire lives competing on the same antler (only leaving to spend the night in nearby vegetation), making it possible to mark flies individually and obtain longitudinal field data on these tiny insects. This unique ecology made it possible to document senescence in wild insects for the first time.^[8]

The waltzing fly,Prochyliza xanthostoma, occurs in North America. It is one of the carrion-feeding piophilids and is remarkable for itssexual dimorphism and its patterns ofbehavioural adaptation and associatedmorphological adaptations. In particular, the antennae, forelegs, and heads of the males are adapted in unusual ways to their behaviour in combat and courtship.^[9] A male courts a female by dancing side-to-side, forequarters held high, displaying his elongated antennae and vibrating his elongated forelegs.^[10]

If swallowed (whether accidentally or otherwise), the larvae sometimes survive in theintestines and pass through the digestive system alive. Such behaviour is known asenteric orintestinalmyiasis. In the gut, the larvae may cause serious lesions by attempting to bore through the intestinal walls. Symptoms includenausea,vomiting, pain in the abdomen, and bloodydiarrhea. Both living and dead larvae may pass in thestool.^[11] Some species also have been known to cause naso-oral and urogenital myiasis.^[1]

Inforensic entomology, the presence ofP. casei larvae may be useful in estimating the date of death for human remains because they do not take up residence in a corpse until three to six months after death.^[12] However,P. casei is not the only piophilid species to attack human corpses, so caution is appropriate in identification of the species found and in interpretation of their significance.^[1][13]

Piophilidae are small flies, often dark in color and shiny. The wings are usually clear and unmarked, with the exception of the generaMycetaulus,Neottiophilum,Pseudoseps, andThyreophora, which have brown wing markings.^[14] Like alltephritoid flies, female piophilids have an extensibleovipositor.

The family differs from the similar looking family Sepsidae in several characters, particularly in having the costa broken at the end of the subcosta, the setulose mesonotum and the absence of a hair or fine bristle arising on the posterior edge of the posterior spiracle of the thorax.

The Piophilidae are a small family of less than 100described species in 21 genera, mainlyHolarctic in distribution, though some species arecosmopolitan. The nomenclature is volatile, with two subfamily names (Neottiophilinae and Thyreophorinae) in use recently, having been subsumed in the subfamily Piophilinae.

The genera of Piophilidae are:^[15]

Recent works containing keys for identification of the Piophilidae include:

• McAlpine, JF (1977). "A revised classification of the Piophilidae, including 'Neottiophilidae' and 'Thyreophoridae' (Diptera: Schizophora)".Memoirs of the Entomological Society of Canada.103:1–66.doi:10.4039/entm109103fv.
• McAlpine JF. (ed.) 1989.Manual of Nearctic Diptera (Vol. 2). Agriculture Canada Monograph No. 32.
• Ozerov, 2000.Piophilidae. In: Papp, L. & Darvas, A. (eds).Contributions to a Manual of Palaearctic Diptera. Appendix Volume. Science Herald, Budapest.pp 355–365.ISBN 963-04-8840-X
• Stackelberg, A.A. Family Piophilidae in Bei-Bienko, G. Ya, 1988Keys to the insects of the European Part of the USSR Volume 5 (Diptera) Part 2 English edition
• Rochefort, S.; et al. (2015). "Key to forensically important Piophilidae (Diptera) in the Nearctic Region".Canadian Journal of Arthropod Identification.27:1–37.

A still useful older work is Séguy, E. (1934)Diptères: Brachycères. II.Muscidae acalypterae, Scatophagidae. Paris: Éditions Faune de France 28Bibliotheque Virtuelle Numerique pdf

• Thyreophora cynophila
• Cheese mite
• Casu marzu

• The Western Palearctic subfamilies, tribes and genera of Piophilidae -Fauna Europaea

• Palaearctic
• Nearctic
• Australasian/Oceanian
• Japan
• World list

• "Antler Flies (Protopiophila litigata)".Evolutionary Biology Lab. University of New South Wales.
• "Waltzing Flies (Prochyliza xanthostoma)".Evolutionary Biology Lab. University of New South Wales.
• Images at Diptera.info

• Berenbaum, May R. (1993).Ninety-Nine More Maggots, Mites, and Munchers. University of Illinois Press.ISBN 978-0-252-06322-0.
• Lieutenant Brian F. Prendergast, USN (2001).Filth Flies: Significance, Surveillance and Control in Contingency Operations (.pdf format). Retrieved 1 October 2005.
• Robinson, W H (2005)."Diptera, Ephemeroptera: Piophilidae: Cheese skipper (Piophila casei)".Handbook of Urban Insects And Arachnids: A Handbook of Urban Entomology. Cambridge University Press. pp. 180–1.ISBN 978-0-521-81253-5.

•   Data related toPiophilidae at Wikispecies
• Family description and images
• An extensive bibliography on the Piophilidae
• Piophila casei on theUF /IFAS Featured Creatures Web site (note that many of the images on this site show other species misidentified as Piophila casei)
• "Piophilidae: Skipper Flies".Atlas of Living Australia.