Female Syrphid flies require pollen in order for their ovaries to mature.
The Painted Wood Fly is rare throughout its range (Skevington et al. 2019) and in New York, it is known from just four occurrences in the central and southeastern portion of the state, none of which is recent. It relies exclusively on old growth deciduous forests for breeding, a rare and threatened habitat.
This species has not been recorded in New York in 40 years.
It was documented only on Staten Island and Long Island in an early comprehensive list of the insects of New York (Leonard 1928), but has only been detected in New York two other times, both in Onondaga County in the late 1970s.
Because the larval habitat is confined to standing senescent trees or very old large decayed stumps found in intact stands of late successional forest, this Hover fly is threatened by modern forestry and land management practices that remove trees from stands before they can reach old age (>100 years) (Speight 2015).
Blera appear to be able to withstand severe genetic bottlenecks, thus allowing viable populations to perist in fragmented woodlands so long as the microclimatic integrity of the late successional forest ecosytem remains intact (Rotheray et al. 2012).
The presence of this species is a clear indication of old growth forest conditions (Skevington et al. 2019). Forest management practices allowing for long rotation times (more than 100 years) are necessary to allow standing deciduous trees to reach the advanced stage where suitable rot-holes can form (Speight 2015).
The endangered Pine Hoverfly (B. fallax) has been actively managed as a conservation target in Scotland since the 1980s. Practical strategies such as breeding habitat creation/improvement and even captive rearing and translocations have shown promising results (Rotheray and Rotheray 2012).
Very little is known about any of the 16 Blera species found in North America. Research into any aspect of their biology would be a valuable contribution.
These pollinators live in old growth deciduous forests (Skevington et al. 2019) with senescent trees where the larvae live in tree rot-holes, wet heart rot cavities and decaying stumps. Greene (1923) found pupa in the frass of a dead Tuliptree (Liriodendron tulipifera) stump in mid April in Virginia. Because the larvae are filter feeders, conditions within the forest must remain stable and humid (Rotheray et al. 2001).
New York lies along the northern range margin of this more southerly species. It is known only from a few scattered locations in central and extreme southeastern New York.
The Painted Wood Fly occurs from Oklahoma and northern Florida, north to southern Michigan and southeastern Maine (Skevington et al. 2019).
The (semi) aquatic larvae of Blera species are maggot-like, except that they possess a long, flexible breathing tube, which allows them to remain submerged in the wet detritus of tree rot holes for extended periods (Rotheray and Rotheray 2012). A puparium is figured in Greene (1923).
This is a distinctive bee-like fly. The adults are about an inch long, having an entirely orange face and yellow markings on tergite 2. The scutum is yellow above the wings and the scutellum is yellow apically (Skevington et al. 2019).
The yellow-orange face and frons, along with its distinctive abdominal markings, distinguish this Wood Fly from other similar flies.
Hover fly puparia and larvae are identifiable (Rotheray 1993), but adults are the easiest to id.
Males fly fast and low in forest clearings near Rubus clumps and are thought to be territorial. They appear to copulate with females in the vicinity of flowers where both sexes feed (Maier 1982; Maier and Waldbauer 1979).
Adults are known to take nectar and pollen from Physocarpus and Prunus (Skevington et al. 2019). Other Blera species also visit Heracleum, Viburnum, Cornus, Sassafrass, Crataegus, Hydrastis, Rhododendron, Acer, Rosa, Rubus, Berberis, Valeriana, Potentilla. The larvae are saprophagous filter feeders in old, senescent (standing) tree rot holes. They are adapted for gathering and concentrating micro-organisms suspended in a fluid medium (Rotheray 2013).
This is a spring species, adults are most likely to be observed in mid- May to early July.
Up to 20% of larvae in a population might extend development for two years (diapause) since they are known to be freeze tolerant. This indicates a semi-voltine development strategy, thereby helping to circumvent population extirpation during unfavorable breeding conditions (cool, rainy June) in a given year (Rotheray et al. 2015).
The time of year you would expect to find Painted Wood Fly reproducing and larvae present and active in New York.
Painted Wood Fly
Blera pictipes (Bigot, 1883)
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Greene, C.T. 1923. A contribution to the biology of N.A Diptera. Proceeding of the Entomological Society of Washington 25:82-90.
Ichige, K, A.V. Barkalov. 2017. A review of the Old World species of the genus Blera. Euroasian Entomological Journal 16:419-431.
Leonard, M. D. ed. 1928. A list of the insects of New York, with a list of the spiders and certain other allied groups. Cornell University Agricultural Experiment Station Mem. 101. Ithaca, New York. 1121 pp.
Maier, C. 1982. Larval habitats and mate-seeking sites of flower flies. Proceedings of the Entomological Society of Washington 84:603-609.
Maier, C., G.P. Waldbauer. 1979. Dual mate-seeking strategies in male syrphid flies. Annals of the Entomological Society of America 72:54-61.
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New York Natural Heritage Program. 2020. New York Natural Heritage Program Databases. Albany, NY.
Rotheray, E.L. 2013. Differences in ecomorphology and microhabitat use of four saproxylic larvae (Diptera: Syrphidae) in Scots pine stump rot holes. Ecological Entomology 38:219-229.
Rotheray, E.L., D. Goulson, L.F. Bussiere. 2016. Growth, development, and life-history strategies in an unpredictable environment: case study of a rare hoverfly Blera fallax. Ecological Entomology 41:85-95.
Rotheray, E.L., O. Lepais, A. Nater, M. Krutzen, M. Greminger, D. Goulson, L.F. Bussiere. 2012. Genetic variation and population decline of an endangered hoverfly Blera fallax. Conservation Genetics 13:1283-1291.
Rotheray, G.E. Color Guide to Hoverfly Larvae in Britain and Europe. Dipterist's Digest 9:1-156.
Rotheray, G.E., EL. Rotheray. 2012. Translocating the Pine Hoverfly, Blera fallax. Antenna 36:36-41.
Rotheray, G.E., G. Hancock, S. Hewitt, D. Horsfield, I. MacGowan, D. Robertson, K. Watt. 2001. The biodiversity and conservation of saproxylic diptera in Scotland. Journal of Insect Conservation 5:77-85.
Skevington, J.H., M.M. Locke, A.D. Young, K. Moran, W.J. Crins, S.A. Marshall. 2019. Field Guide to the Flower Flies of Northeastern North America. Princeton University Press, 512 p.
Speight, M.C.D. 2015. Species accounts of European Syrphidae (Diptera), 2015 (Vol. 83). Dublin: Syrph the Net Publications.
Thompson, F.C. 2000. A new Blera (Diptera: Syrphidae). Entomological News 111:181-184.
Wheeler, A.G., E.R. Hoebke 1985. The insect fauna of Ninebark, Physocarpus opulifolius. Proceedings of the Entomological Society of Washington 87:356-370.
This guide was authored by: Jeff Corser
Information for this guide was last updated on: March 26, 2019
Please cite this page as:
New York Natural Heritage Program. 2020. Online Conservation Guide for Blera pictipes. Available from: https://guides.nynhp.org/painted-wood-fly/. Accessed September 26, 2020.