Identification key to species of myiasis-causing fly larvae

This key, developed by Zoe Adams, Lisa Smith and Martin Hall, is a work in progress and will be updated on a regular basis to include more taxa and characters. Currently it will identify to species only the most commonly encountered taxa, with special emphasis on those species of particular economic importance.

Aims of the key

Identification of eggs, first, and second instar larvae by morphological characters can be extremely difficult, and, because these stages are relatively short lived and seldom encountered during the collection of specimens from infested wounds, they will not be considered further here. This identification aid will concentrate on third instar larvae.

Both the Old World screwworm fly (OWSF) Chrysomya bezziana and the New World screwworm fly (NWSF) Cochliomyia hominovorax are major economic pests. Identification of either of these species from a region where they are not endemic is a serious matter and you should have your identification confirmed by an expert on this group of insects.

Both OWSF and NWSF are recognised as important, transboundary, economic pests of livestock and are listed under the multiple species disease category in the Terrestrial Animal Health Code (2007) of the World Organization for Animal Health (OIE).

Key design

The interactive multi-access design of the identification key allows you to select which characters to examine and in which order to examine them.

The key was constructed with the LUCID 3.4 key-building software (from Lucidcentral) and is being run using a Java applet. This may require an update of the Java software to be downloaded to your computer (see LUCID's help on Java). You may also be invited to register with LUCID for news of updates, but this is not essential.


This key was made possible through a start-up grant from the Food and Agriculture Organization (FAO).

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    Introduction to myiasis

    The term myiasis was first proposed by Hope (1840) to refer to diseases of humans originating specifically with dipterous larvae, as opposed to those caused by insect larvae in general, scholechiasis (Kirby and Spence, 1815).

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    Launch the key to myiasis-causing larvae

    Upload the Java applet and run the LUCID identification key (this will take you out of the NHM website).

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    How to use the key

    A step-by-step outline guide to running the identification key. More detailed assistance can be gained by accessing the LUCID player help files.

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    Collecting and processing specimens

    Manual removal of calliphorid and sarcophagid larvae in cases of traumatic myiasis may be achieved by forceps.

Contact us

Martin Hall

Collaborating Centre on Myiasis-Causing Insects and Their Identification for the Food and Agriculture Organisation of the United Nations
Division of Parasites and Vectors,
Department of Life sciences,
Natural History Museum,
Cromwell Road,
SW7 5BD,

Fax: +44 (0)20 7942 5229 

Email us