Taxonomy
Eumerus strigatus
Distribution
Species Biology
Preferred environment
Wetland/forest/open ground; unimproved, humid, seasonally-flooded grassland, deciduous forest and open, dry unimproved pasture, including dune grassland; to some extent anthropochorous, occurring sometimes in horticultural land and suburban gardens. If E. strigatus is an indigenous species, in that it first arrived in Ireland during the postglacial unaided by man's activities, its natural habitat here may well be coastal grassland, given that existing records away from coastal grassland are nearly all from habitats introduced to Ireland by man's activites and dependent upon man's activities for their continued existence. However, E. strigatus is one of a small number of European Eumerus species (E. amoenus (Lw), E. funeralis (Mg.) and E. sogdianus Stack. would be other examples) that have been able to make use of part of the heterogenous assemblage of bulb, corm and tuber-making plants distributed round Europe by human activity, for use as either vegetables or ornamental garden plants. E. strigatus has certainly been introduced to parts of the world well outside its natural range with such plants and will almost certainly have reached Ireland in this way, whether or no an indigenous population of the species was here already. One definite consequence is that E. strigatus can be found today in Ireland in a variety of situations in addition to coastal grassland, including, on occasion, farmland and artificial habitat like suburban gardens. Various of the introduced plants that could act as hosts for E. strigatus larvae establish themselves, at least temporarily, along hedge margins, in rubbish dumps etc., providing a probable explanation for the appearance of E. strigatus in unexpected situations. It is quite possible that E. strigatus can also use one or another of the various wild umbellifers (Apiaceae) occurring in Ireland as a larval food plant, one candidate being pignut (Conopodium). But there is little constancy to the occurrence of E. strigatus in semi-natural/natural habitats away from coastal grassland in Ireland. It would seem possible that the consistent occurrence of E. strigatus in association with coastal grasslands in the south east of the island is due to the suitability of soils there for growing potatoes (one alternative food for E. strigatus is rotting potato tubers). The available data would seem more indicative of a recent, man-made introduction of E. strigatus to Ireland than of natural occurrence of the species in the island.
Adult habitat & habits
Among thick vegetation of humid grassland, edges of clearings and tracks, etc.; flies low, usually keeping within vegetation; in dry grassland often settles on the ground, on stones etc.
Flight period
May/September, with peaks in June and August. Larva: described and figured by Heiss (1938); bulb feeder, recorded from Liliaceae, parsnip, carrot, potato, asparagus, artichoke roots (Cynara scolymus) and also from rotting grapefruit; regarded as a minor pest of horticulture, but apparently only attacks bulbs etc. when they are rotting. This species overwinters as a larva (Brunel and Cadou (1994).
Flowers visited
Umbellifers; Allium ursinum, Convolvulus, Eschscholzia californica, Euphorbia, Fragaria, Leontodon, Papaver, Potentilla erecta, Ranunculus, Sonchus arvensis, Taraxacum.
Irish reference specimens
In the collections of NMI and UM
Determination
van der Goot (1981), Bradescu (1991).The adult insect is illustrated in colour by Bartsch et al (2009b), Kormann (1988), Stubbs and Falk (1983), Torp (1984, 1994) and van der Goot (1986).
Distribution
World distribution(GBIF)
Fennoscandia south to Iberia and the Mediterranean; much of Europe through into Turkey and Russia; from the Urals to the Pacific coast (Sakhalin); Japan; introduced to N America and recorded from both Canada and the USA; introduced to both Australia and New Zealand. It is frequent over most of Europe south of Scandinavia and, through human transport, is becoming cosmopolitan.
Irish distribution
Recorded as occurring in Ireland in Coe (1953). Largely confined to the southern half of the island, and with most records from the south-east. Where it occurs, E. strigatus is often present in dense, populous colonies. It is by no means a threatened insect in Ireland, and can be expected to expand and consolidate its range here.
Temporal change
Records submitted to Data Centre in 2024
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References
Publications
Speight, M. C. D. (2008) Database of Irish Syrphidae
(Diptera). Irish Wildlife Manuals, No. 36. National Parks and Wildlife Service.
Department of Environment, Heritage and Local Government, Dublin, Ireland.
Speight, M.C.D. (2014) Species accounts of European
Syrphidae (Diptera), 2014. Syrph the Net, the database of European Syrphidae,
vol. 78, 321 pp., Syrph the Net publications, Dublin.