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Huttons flower fly - Aphanotrigonum huttoni

By N A Martin (2017)

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Click to collapse Classification Info






Aphanotrigonum huttoni (Malloch, 1931)

Click to collapse Common names Info

Hutton’s flower fly, Nikau palm flower fly

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Oscinosoma huttoni Malloch, 1931

Caviceps huttoni (Malloch, 1931)

Click to collapse Biostatus and distribution Info

This endemic fly is found throughout New Zealand. The adult flies are associated with flowers and are often abundant on flowers of nikau palm Rhopalostylis sapida (Palmae). The larvae live in decaying leaves.

Conservation status: Widespread in parks and gardens as well as native habitats, not threatened.

Click to collapse Life stages and annual cycle Info

Adult flies are found in flowers in spring, summer and autumn. They feed in the flowers. They are especially abundant on male flowers of Nikau palms Rhopalostylis sapida (Palmae) and presumably feed on pollen as well as nectar. Males and females mate on the flowers. There are probably several generations per year. Larvae live in decaying leaves.

Adult fly

The adult flies are small, about 2.0-2.5 mm long, much smaller than vinegar flies, Drosophila, that are seen around rotting fruit. The flies are yellow-brown with three darker brown stripes on the thorax (middle part of the body) and darker bands on some abdominal segments. The intensity and width of the dark brown stripes and bands varies greatly. Like all adult flies they have three pairs of legs and one pair of wings. The hind pair of wings is reduced to two small knobs, or halteres, which help the fly to balance during flight. The male has a rounded end of the abdomen, while the female has a slender end containing an ovipositor which is presumably used to insert eggs into decaying leaves.

Larvae and Pupae

The white larvae feed on decaying leaves. When fully grown, the larva pupates inside its larval skin, which turns brown and hard. This structure is called a puparium.

Click to collapse Recognition Info

These small yellow and brown flies require expert knowledge for identification. However, adults of this species can be easily recognised on flowers by their small size and yellow-brown colour and the three dark brown stripes on the thorax (middle section of the body).

White fly larvae on decaying leaves need to be reared so that the adults can be identified.

Click to collapse Natural enemies Info


One bird has been recorded feeding on adult flies. There are no reports of predators of the flies, but it is likely that they are preyed upon by birds, spiders and predatory insects.


One larval-pupal parasitoid was found in pupae in dead leaves of New Zealand climbing spinach, Tetragonia implexicoma (Aizoaceae). Adult female wasps of Asobara albiclava (Hymenoptera: Braconidae), lay eggs in fly larvae associated with decaying leaves. The parasitoid larva kills the fly after it has pupated.

Table: Natural enemies of Hutton's flower fly, Aphanotrigonum huttoni (Diptera: Chloropidae), from Plant-SyNZ database (15 March 2017). The reliability index shows the quality of evidence for the host association (0-10, 10=high quality).
Scientific NameCommon NameClassificationEnemy TypeReliability IndexBiostatus
Asobara albiclava Berry, 2007 (Wasp)Hymenoptera: Braconidaeparasitoid10endemic
Bowdleria punctata Quoy & Gaimard, 1830Snares fernbird (Bird)Passeriformes: Sylviidaepredator10endemic

Click to collapse Host plants Info

Adults of this species of fly are found on flowers where they feed and mate. Large numbers are found on some species of flower. In Auckland, they are especially abundant on nikau palm, Rhopalostylis sapida (Palmae). They appear to feed on both nectar and pollen.

The fly larvae live in decaying plants. Adult flies have been reared from larvae in decaying leaves of New Zealand climbing spinach, Tetragonia implexicoma (Aizoaceae) and New Zealand celery, Apium prostratum (Umbelliferae).

Table: Host plants of the Hutton's flower fly, Aphanotrigonum huttoni (Diptera: Chloropidae) from Plant-SyNZ database (15 March 2017). The reliability score shows the quality of evidence for the host association (1-10, 10=high).
Common Name(s)Scientific NameFamilyReliability IndexBiostatus
New Zealand celery, Sea celery, Shore celery, Tūtae kōau Apium prostratum Labill. ex Vent.Umbelliferae10non-endemic
New Zealand climbing spinach, Kōkihi, Rengamutu, Rengarenga, Tūtae-ikamoanaTetragonia implexicoma (Miq.) Hook.f.Aizoaceae10non-endemic
 Anisotome acutifolia (Kirk) CockayneUmbelliferae10endemic
Stewart island tree groundselBrachyglottis stewartiae (J.B.Armstr.) B.Nord.Compositae10endemic
Three Kings cabbage treeCordyline obtecta (Graham) BakerAsparagaceae9non-endemic
Deciduous lacebark, Mountain lacebark, Hoihere, Houhere, Houhi, Houī, WhauwhiHoheria glabrata Sprague & Summerh.Malvaceae10endemic
Lacebark, Hohere, Hoihere, Houhere, Houhi, Houhi ongaonga, Houī, Ongaonga, Whauahi, WheuhiHoheria populnea A.CunnMalvaceae10endemic
Broadleaf privet, Tree privetLigustrum lucidum W.T.AitonOleaceae10naturalised
Large-leaved muehlenbeckia, Pōhuehue, PukaMuehlenbeckia australis (G.Forst.) Meisn.Polygonaceae10non-endemic
Kermadec Island palm, Kermadec Island nikauRhopalostylis baueri (Seem.) H.Wendl. & DrudePalmae10non-endemic
Feather duster palm, Nikau palm, NīkauRhopalostylis sapida H.Wendl. & DrudePalmae10endemic

Click to collapse Additional information Info

Research project: Where are the larvae of Hutton’s flower fly

Large numbers of adult flies on favoured flowers indicate that the flies are breeding somewhere nearby. It is easy to collect and keep adult flies. Adult flies have been reared from decaying leaves of two plants. What are the other plants on which they live? It would be possible to test a variety of substrates for their suitability for egg laying and for their ability to support larval development.

Click to collapse Information sources Info

Harrison RA. 1959. Acalypterate Diptera of New Zealand. N.Z. Department of Scientific and Industrial Research Bulletin. 128: 1-382.

Plant-SyNZ: Invertebrate herbivore-host plant association database.

Spencer KA. 1977. A revision of New Zealand Chloropidae. Journal of the Royal Society of New Zealand. 7 (4): 433-472.

Click to collapse Acknowledgements Info

The New Zealand Institute for Plant & Food Research Limited (Plant & Food Research) for permission to use photographs.

Landcare Research New Zealand Limited (Landcare Research) for permission to use photographs.

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