Full-text - Norsk entomologisk forening

numbers at the sites. This is a trend in theNorwegian collections also, and especiallywhen a sweep-net has been used for collecting.The flight period of B. nigriventris isshown in Fig. 2, and here material from occasionalcatches and Malaise-traps have beenconsidered. The flight period ofB. nigriventrisis found to be late May to first part of Julyin southern Norway, while the records fromnorthern Norway indicate late July to earlyAugust. This delay is certainly caused by alater spring in northern Norway comparedwith southern Norway. The climatic variationsthat occur from the extreme coast toareas having more continental climate doesnot influence on the flight period of B. nigriventris.Specimens appeared in Malaise trapsat the same time at these two areas.The earliest record on an annual basis isrepresented by a specimen taken 5 May atHolmsbu, Hurum, Buskerud province, andthe latest record is 4 August at Urskar, Bod0,Nordland. Freeman & Lane (1985) noted theflight period to be May-July at the BritishIsles, which is fairly similar to the flight periodin southern Norway. Pecina (1965) reportedthe flight period to be May--June inthe lowlands while specimens were collectedin late July in the mountains ofCzechoslovakia.The flight period of B. nigriventris in themountains of Czechoslovakia correspondswith the few findings in the Norwegian montains.In the total material the sex ratio is I: I. InMalaise-trap collections, however, the malesoutnumbered the females, e.g. at B0, Hurum:Tofte, the sex ratio was 2 males per I female.This indicate that the males move aroundmuch more than the females.ACKNOWLEDGEMENTSI am indepted to J.E. Raastad, Museum ofZoology, University of Oslo, John O. Solem,The Museum, University of Trondheim andPer Straumfors, Rana Museum for loan ofmaterial. My thanks are due to the followingpersons who collected parts of the material:Tor & Sissel Fjelldal, Bergen; Fred Midtgaard,As; Tore R. Nielsen, Sandnes; and last,but not least my collegues Torstein Solh0Yand Arild Fjeldsa.REFERENCESFreeman, P. & Lane, R.P. 1985. Bibionid andScatopsid flies. Diptera: Bibionidae and Scatopsidae.Hand. ident. Br. Insects 9 (7). 74 pp.London.Greve, L. 1986. Bibio marci (L. 1758) (Dipt. Bibionidae)new to the Norwegian fauna. Faunanorv. Ser. B 33, 103.Greve, L., Solem, 1.0. & Olsen, A. 1984. Distributionand flight periods of Bibionidae (Dipt.)in the Dovrefjell mountains near Kongsvoll,Central Norway. Fauna norv. Ser. B 31,88­91.Hackman, W. 1980. A checklist of Finnish Diptera.I. Nematocera and Brachycera (s.str.) Notulent. 60, 17-48.Haenni, 1.-P. 1982. Revision des especes europeennesde groupe de Dilophus febrilis (L.) avecdescription d'une espece nouvelle (Diptera, Bibionidae).Revue suissl! Zool. 89, 337-354.Pecina, P. 1965. Bohemian March-flies (Diptera,Bibionidae) in the National Museum, Prague.Sb. fauna Praci ent. Odd. mir. Mus. Praze 11,285-297.Siebke, H. 1877. Enumeratio Insectorum NorvegicorumFasciculum IV. Catalogum DipterorumContinentem. A.W. Br0gger, Christiania. 255pp.Strand, E. 1913. Neue Beitrage zur AnthropodenfaunaNorwegens nebst gelegentlichen Bemerkungeniiber Deutsche arten. XVI-XX. XVI.Lundstrom: Diptera Nematocera. Nyt Mag. Naturv.51, p. 311.Solem, 1.0. 1985. Distribution and biology ofcaddisflies (Trichoptera) in Dovrefjell mountains,Central Norway. Fauna norv. Ser. B 32,62-79.Verbeke, 1. 1971. Bibionidae de la fauna Beige. I.Le genre Bibio Geoffroy. Bull. Inst. r. Sci. nat.Berg. 47, 1-22.Wahlgren, E. 1919. Diptera. F0rsta underordningen.Myggor. Nemocera. Fam. Bibionidae.Svensk insektsfauna, 131-140.Received 25 April 198634