The Coelopidae or kelp flies are a family of Acalyptratae flies (order Diptera), they are sometimes also called seaweed flies, though both terms are used for a number of seashore Diptera. Fewer than 40 species occur worldwide. The family is found in temperate areas, with species occurring in the southern Afrotropical, Holarctic, and Australasian (which has the most species) regions.

Coelopa frigida morphology
Seaweed or kelp flies
Kelp Fly (Coelopa)
Scientific classification

Hendel, 1910
  • Coelopinae Meigen, 1830
  • Lopinae McAlpine, 1991

Family characteristics

Coelopids are small to medium-sized (2.5–9 mm (0.098–0.35 in), usually 4–7 mm (0.16–0.28 in)), robust flies, predominantly with a flat body and darkly coloured. Coelopidae species are usually densely bristly or hairy. Their eyes are small. The arista is bare to pubescent. Ocelli and ocellar bristles are present. The postvertical bristles are parallel or converge. The two pairs of frontal bristles curve outward and scattered interfrontal setulae are present. Vibrissae are absent, but strong bristles occur near the vibrissal angle. The mesonotum is flat and the prothorax is separated from the propleuron by a membrane. The legs bear strong bristles and soft, dense hairs and the tibiae have subapical bristles. The wing is unmarked. The costa is entire, without interruptions. The subcosta is complete, crossvein BM-Cu is present, and the anal cell (cell cup) is closed. Legs usually densely hairy.


Coelopids are found in the wrack zone of temperate seashores where the larvae feed on rotting seaweed. They are sometimes very abundant in this habitat. They go through several generations a year. The females lay their eggs in small batches into fresh alga banks. Three larval instars occur. Larvae feed in a bacteria-laden mass. Pupation is seldom in the algal substrate that soon collapses, but more frequently in the highest sand layers. Larvae are also found in winter wrack heaps as bacteria raise temperatures to 20-30 °C even if the heap is superficially frozen. Larvae and pupae have numerous predators, including birds and the staphylinid Aleochara and suites of parasites confined to algal banks.


As of 2011, following Mathis and McAlpine's taxonomy, Coelopidae consists of two subfamilies: Coelopinae, with three tribes, twelve genera, and twenty-eight species, and Lopinae, consisting of just one monospecific genus.[1]

  • Subfamily Coelopinae Hendel, 1910
    • Tribe Coelopini Hendel, 1910
    • Tribe Coelopellini McAlpine, 1991
      • Genus Amma McAlpine, 1991
      • Genus Beaopterus Lamb, 1909
      • Genus Coelopella Malloch, 1933
      • Genus Icaridion Lamb, 1909 Halteres absent and the wings are reduced to strips.New Zealand.
      • Genus Rhis McAlpine, 1991
      • Genus This McAlpine, 1991
    • Tribe Glumini McAlpine, 1991
      • Genus Chaetocoelopa Malloch, 1933
      • Genus Coelopina Malloch, 1933
      • Genus Dasycoelopa Malloch, 1933
      • Genus Gluma McAlpine, 1991
      • Genus Malacomyia Haliday in Westwood, 1840 (sometimes placed in Dryomyzidae)
  • Subfamily Lopinae McAlpine, 1991
    • Genus Lopa McAlpine, 1991


Coelopa frigida (Fabricius) has been reared in the laboratory and used for genetic studies.

See also


  1. ^ Mathis, Wayne N.; McAlpine, David K. (2011). "A Catalog and Conspectus on the Family Coelopidae (Diptera: Schizophora)". In Brake, Irina; Thompson, F. Christian (eds.). Contributions to the Systema Dipterorum (Insecta: Diptera). Myia. 12. pp. 171–205. hdl:10088/18924. ISBN 978-954-642-599-7.

Further reading

  • McAlpine, David K. (1991). "Review of the Australian Kelp Flies (Diptera: Coelopidae)". Systematic Entomology. 16: 29–84. doi:10.1111/j.1365-3113.1991.tb00573.x.
  • McAlpine, David K. (1998). "Family Coelopidae". In Papp, L.; Darvas, B. (eds.). Contributions to a Manual of Palaearctic Diptera. 3. Budapest: Science Herald. pp. 335–340.
  • Meier, Rudolf; Wiegmann, Brian M. (2002). "A phylogenetic analysis of Coelopidae (Diptera) based on morphological and DNA sequence data". Molecular Phylogenetics and Evolution. 25 (3): 393–407. doi:10.1016/S1055-7903(02)00276-2.

External links


  • Hennig. 1937. Coelopidae.In: Lindner, E. (Ed.). Die Fliegen der palaearktischen Region 5, 52, 1-38.Keys to Palaearctic species but now needs revision (in German).
  • Malloch, J.R. 1933. The genus Coelopa Meigen (Diptera, Coelopidae). Ann. Mag. Nat. Hist. (10) 11: 339-50.
  • McAlpine, David K. (1991). "Review of the Australian Kelp Flies (Diptera: Coelopidae)" (Print). Systematic Entomology 16: 29-84.
  • Séguy, E. (1934) Diptères: Brachycères. II. Muscidae acalypterae, Scatophagidae. Paris: Éditions Faune de France 28. virtuelle numérique
  • Shtakel'berg, A.A. Family Coelopidae in Bei-Bienko, G. Ya, 1988 Keys to the insects of the European Part of the USSR Volume 5 (Diptera) Part 2 English edition.Keys to Palaearctic species but now needs revision .

Species lists


The Acalyptratae or Acalyptrata are a subsection of the Schizophora, which are a section of the order Diptera, the "true flies". In various contexts the Acalyptratae also are referred to informally as the acalyptrate muscoids, or acalyptrates, as opposed to the Calyptratae. All forms of the name refer to the lack of calypters in the members of this subsection of flies. An alternative name, Acalypterae is current, though in minority usage. It was first used by Justin Pierre Marie Macquart in 1835 for a section of his tribe Muscides; he used it to refer to all acalyptrates plus scathophagids and phorids, but excluding Conopidae.

The confusing forms of the names stem from their first usage; Acalyptratae and Acalyptrata actually are adjectival forms in New Latin. They were coined in the mid 19th century in contexts such as "Muscae Calyptratae and Acalyptratae" and "Diptera Acalyptrata", and the forms stuck.The Acalyptratae are a large assemblage, exhibiting very diverse habits, with one notable and perhaps surprising exception: no known acalyptrates are obligate blood-feeders (hematophagous), though blood feeding at various stages of the life history is common throughout other Dipteran sections.


The Brachyceran infraorder Asilomorpha is a large and diverse group of flies, containing the bulk of the nonmuscoid Brachycera. The larvae of asilomorphs are extremely diverse in habits, as well.


Calyptratae is a subsection of Schizophora in the insect order Diptera, commonly referred to as the calyptrate muscoids (or simply calyptrates). It consists of those flies which possess a calypter that covers the halteres, among which are some of the most familiar of all flies, such as the house fly.

About 18,000 described species are in this group, or about 12% of all the flies yet described.


Carnoidea are a superfamily of Acalyptratae flies.

Chaetocoelopa littoralis

Chaetocoelopa littoralis, commonly known as the hairy kelp fly, is a fly of the family Coelopidae. It is endemic to New Zealand. These flies are black in appearance and show large variation in size, with males tending to be larger and more robust and 'hairy' than females. C. littoralis can also be observed resting on surfaces including cliff faces and driftwood in large aggregations.


The Chironomoidea are a superfamily within the order Diptera, suborder Nematocera, infraorder Culicomorpha. This superfamily contains the families Chironomidae, Ceratopogonidae, Simuliidae, and Thaumaleidae. One of the more important characteristics used to define them is the form of the larval mouthparts.


Coelopa is a genus of kelp flies in the family Coelopidae. There are about 13 described species in Coelopa.

Coelopa vanduzeei

Coelopa vanduzeei is a species of kelp flies in the family Coelopidae.


The Culicoidea are a superfamily within the order Diptera. The following families are included within the Culicoidea:

Dixidae – meniscus midges

Corethrellidae – frog-biting midges

Chaoboridae – phantom midges

Culicidae – mosquitoes


The Culicomorpha are an infraorder of Nematocera, including mosquitoes, black flies, and several extant and extinct families of insects.


The Helcomyzidae are a small family of flies in the Acalyptratae. The larvae feed on kelp and other organic matter washed up on shorelines. Species diversity is highest in New Zealand and south temperate South America. They are sometimes allied with the families Dryomyzidae or Coelopidae.


Heterocheila is a genus of acalyptrate true flies (Diptera). They are placed in their own family, Heterocheilidae, in the superfamily Sciomyzoidea. They are not widely familiar outside entomological circles, but the common name "half-bridge flies" has been associated with them. They are medium-sized flies occurring mainly in temperate regions on seashores of the Northern Hemisphere, where they and their larvae typically feed on stranded kelp in the wrack zone. In this, they resemble kelp flies, which are members of a different family, though the same superfamily.

The family Heterocheilidae was established by McAlpine in 1991. He distinguished it from other families to which Heterocheila had hitherto been referred at various times and by various authorities – Helcomyzidae, Dryomyzidae and Coelopidae.

Kelp fly

Kelp fly is one common name of species of flies in a number of families of "true flies" or Diptera. They generally feed on stranded and rotting seaweed, particularly kelp in the wrack zone. When conditions are suitable they are very numerous and may be ecologically important in the turnover of organic material on the coast. In this role they also may be an important item in the diet of beach-dwelling animals and birds. The flies most generally referred to as kelp flies are the widely distributed Coelopidae. In popular speech however, they are not clearly distinguished from other flies with similar feeding habits, such as the Heterocheilidae, the Helcomyzinae and sundry members of the Anthomyiidae.


Oestroidea is a superfamily of Calyptratae including the blow flies, bot flies, flesh flies, and their relatives.The superfamily includes the families:


Mesembrinellidae (formerly included in Calliphoridae)



Rhiniidae (formerly included in Calliphoridae)






Sciomyzoidea is a superfamily of Acalyptratae flies.

The families placed here are:

Coelopidae – seaweed flies






Sepsidae – scavenger flies

Sciomyzidae – marsh flies, snail-killing flies (including Huttoninidae, Phaeomyiidae, Tetanoceridae)


Superfamily Tabanoidea are insects in the order Diptera.


The Tephritoidea are a superfamily of flies. The following families are included:

Pallopteridae — flutter flies

Piophilidae — skippers

Platystomatidae — signal flies



Tephritidae — fruit flies

Ulidiidae (Otitidae) — picture-winged fliesThe Tachiniscinae, formerly ranked as the family Tachiniscidae, are now included in the Tephritidae.

This (fly)

This is a genus of kelp fly in the family Coelopidae. As of 2017, it is monotypic, consisting of its type species This canus. This and T. canus were respectively circumscribed and described in 1991 by the Australian entomologist David K. McAlpine. It is endemic to southern Australia.


The Tipulomorpha are an infraorder of Nematocera, containing the crane flies, a very large group, and allied families.

One recent classification based largely on fossils splits this group into a series of extinct superfamilies (below), and includes members of other infraorders, but this has not gained wide acceptance.

Extant Diptera families


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