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Phenology and species composition of Syrphidae (Dipt.)in a meadow habitatELINE BENESTAD HAGVARHagvar, E.B. 1983. Phenology and species composition of Syrphidae (Dipt.) in a meadowhabitat. Fauna norv. Ser. B, 30,84-87.Species composition of adult syrphids was studied from May to October in a meadow habitatat Gaustad, Oslo, during 1970 and 1971. Duration of flowering in dominant plant specieswas also recorded. Twenty-eight syrphid species were identified. Species richness culminatedin August. Most abundant species were Syrphus ribesii (L.l, Sphaerophoria scripta (L.l,Sphaerophoria taeniata (Meigen), Eristalis arbustorum (L.l, Syrphus vitripennis Meigen, ~Episyrphus ba/teatus (DeGeerl and Syritta pipiens (L)Eline Benestad Hagvar, Agricultural University of Norway, Department of Zoology, Box46, N-1432 Aas-NLH, Norway.INTRODUCTIONwere made about the visual impression of syrp-'hid species dominance in the hSlbitat.The main intention of this work was to regi­In both years. syrphids were collected mainlystrate which syrphid species occur during a seaonsunny days with little wind.son in a meadow habitat in south east of Nor­way. With the exception of Nielsen's (I 971 ,1972) studies at Jreren, western Norway, suchsyrphid investigations have not previously been RESULTSperformed in this country. The sampling tech­The vegetation was not quantitatively analysed.nics were inadequate to present a quantitativeHowever, fig. I illustrates the duration of flowepictureof the fauna.ring in dominant plant species through a season,based on an average for the two years.MATERIAL AND METHODSThe picture was about the same in both years,except for Cirsium arvense (L.) which in 1970Adult syrphids were collected from a meadow had a somewhat shorter flowering period thanhabitat at Gaustad, Oslo, in 1970 and 1971. The in 1971, probably caused by more heavy infestasamplingarea measured 10 x 20 m and was part tion by the bean aphid, Aphis fabae Scopoli.of a larger open area sloping towards east. The Bean aphids were also observed on Matricavegetationin the sampling area differed somew­ ria indora L. The dominant flowering plant spehatin plant dominance from that of the surro­ cies through most ofthe season were C. arvense,unding meadow.M. indora and Achillea millefolium L. M. indoraIn 1970 only adult syrphids in the air or expo­ obviously served as a valuable pollen source,sed on the vegetation were captured, by sweep­ and adult syrphids were often observed on thisnetting for 1-2 I /2 hours. In 1971, this met­ plant. Egglaying syrphids were apparently athodwas supplemented by sweep-netting in the tracted by the heavily aphid infested C. arvense, t,vegetation, with 200 strokes at each sampling. syrphid eggs and larvae being quite commonlySampling dates in 1970 were: 17, 20,23 and 29 observed in July and August on this plant.July; 10, 24 and 26 August; and 7 and 12 Sep­ Twenty-eight identified syrphid species weretember. Sampling dates in 1971 were: 19 May; 4 collected from the habitat (Fig. 2). No females ofand 23 June; 3 July; 6, 9, 20 and 31 August; 10 Sphaerophoria have been identified to species.September; and I October. On 20 July and 10 The figure illustrates the change in speciesAugust 1970 some syrphid larvae were collected composition in the habitat for both years. Becaandreared to adults in the laboratory. Because use of the unreliable quantitative sampling techthesampling techniques are not strictly quanti­ niques. only the presence of a species and nottative and may also be selective, additional notes the number of specimens at each sampling is gi-84Fauna norv. Ser. B. 30,84-87. Oslo 1983