Dipterists Digest 2019 26, 71-72
The family Cryptochetidae (Diptera) new to Britain, with the first
European record of Cryptochetum iceryae (Williston) –
On 15 May 2018,
one of us (DN) collected two small dipterans as part of routine sampling of the Natural History
Museum’s Wildlife Garden (London, South Kensington). The specimens were swept from the
meadow habitat of the garden, in an area rich in flowering herbs. They were immediately
identified as belonging to the family Cryptochetidae and the finding was briefly mentioned by C.
Ware et al. (2018. The Wildlife Garden at the Natural History Museum: developments of the flora
and fauna update 2017-2018 – twenty three years of species recording. London Naturalist 97,
135-152). This was later confirmed when these specimens were identified as males of
Cryptochetum iceryae (Williston, 1888), after comparison with specimens in the Natural History
Museum collection (NHMUK) and California State Collection of Arthropods (CDFA,
Sacramento). Both specimens have body and wing lengths of ca 2 mm, metallic bluish-purple
reflections on the head and thorax, a metallic green abdomen, a broad ocellar triangle occupying
most of the frons width at vertex and about 0.25 of the frons width anteriorly, and modified
setation on the fore tarsus (Figs 1-2).
Cryptochetidae is a small family of acalyptrate flies in the superfamily Ephydroidea,
possibly closely related to Braulidae (“bee lice”) (Wiegmann, B.M. et al. 2011. Episodic
radiations in the fly tree of life. PNAS 108(14), 5690-5695). The larvae are parasitoids of scale
insects and the adults are easily recognised by their small but stout appearance and large antennae,
which lack an arista in species of Cryptochetum Rondani, the largest and most widespread genus
(Marshall, S.A. 2012. Flies: the natural history and diversity of Diptera. Firefly Books,
Buffalo/Richmond Hill). The family is native to the Old World, with about 30 species in two
genera in the Afrotropical, Palaearctic, Oriental and Australasian Regions (McAlpine, J.F. and
Thompson, F.C. 2010. Cryptochetidae (cryptochetid flies), pp. 1121-1123. In Brown, B.V. et al.
Manual of Central American Diptera. Vol. 2. NRC Research Press, Ottawa). Three species, all
in the genus Cryptochetum, were so far known to occur in Europe (Nartshuk, E. 2013.
Cryptochetidae. In Beuk, P. and Pape, T. (Eds) Diptera: Brachycera. Fauna Europaea,
Figs 1-2. Male Cryptochetum iceryae (Willistion) from the NHM’s Wildlife Garden; 1,
NHMUK012809016, arrow showing modified setae on fore tarsus; 2, NHMUK012809017.
© Trustees of the Natural History Museum.
Cryptochetum iceryae, originally described from Australia, has been introduced to North
and South America and Israel for biocontrol of the widespread pest Icerya purchasi Maskell,
1878 (Homoptera: Monophlebidae) or cottony cushion scale (Mendel, Z. and Blumberg, D. 1991.
Colonization trials with Cryptochetum iceryae and Rodolia iceryae for improved biological
control of Icerya purchasi in Israel. Biological Control 1(1), 68-74; McAlpine and Thompson,
op. cit.). The current records of C. iceryae are the first in Europe and the first for the family
Cryptochetidae in Britain. It is likely that these specimens arrived in Central London with
imported plants infested with their host. Icerya purchasi has been intercepted numerous times on
imported ornamental plants in Britain and has been recorded as breeding outdoors at several sites
in South East England, particularly in Greater London (Watson, G.W. and Malumphy, C.P. 2004.
Icerya purchasi Maskell, cottony cushion scale (Hemiptera: Margarodidae), causing damage to
ornamental plants growing outdoors in London. British Journal of Entomology & Natural History
17, 105-109). Cottony cushion scale has also been recorded on gorse (Ulex europaeus) in the
NHM’s Wildlife Garden by C. Ware et al. (2016. Further developments of the flora and fauna of
the Wildlife Garden at the Natural History Museum, London: twenty years of species recording.
London Naturalist 95, 45-159), but was not observed at the time of collection of C. iceryae in
2018. Cryptochetum iceryae was not collected again despite several searches of the same habitat
during the weeks following its discovery. It is difficult to assess, with the limited available data,
whether or not a population has become locally established.
Records: Cryptochetum iceryae: 2 males, UK, London, Natural History Museum Wildlife
Garden, TQ26557903, 15.V.2018, D. Notton. Both specimens are deposited at NHMUK
(specimen numbers 012809016 and 012809217).
We thank Steve Gaimari and Martin Hauser (CDFA, Sacramento) for the donation of C.
iceryae specimens from California
Staatliches Museum für
Naturkunde Stuttgart, Rosenstein 1, 70191 Stuttgart, Germany; email@example.com,
DAVID G. NOTTON,
Department of Life Sciences, Natural History Museum, Cromwell
Road, London SW7 5BD, United Kingdom, and
67 Giffard Way, Long
Crendon, Aylesbury, Buckinghamshire HP18 9DN, United Kingdom