Emergence traps were operated over three years in a stream near Lunz in southwestern Lower Austria, to find out the differences between eight types of traps. Trichoptera, Plecoptera, Ephemeroptera, Simuliidae, Limoniidae and Empididae were compared quantitatively as whole groups. Trichoptera, Limoniidae and aquatic Empididae were compared at species level. Except for the expected statistical variation, there was wide variation in the number of specimens between groups and species, and also between the trap types, to such a degree that the emergence method appears to be of limited value for productivity or other quantitativestudies. The total catch of insects caught in the traps, consisted of freshly emerged adults, aged ovipositing females and many other insects (including terrestrial ones) which entered the traps in unknown ways. The variation may depend on the biology and behaviour of the insects, on the design of the traps and on an unknown number of other factors.

Twenty-two species of aquatic Diptera have been collected from 16 sites on the Iberian peninsula. Three Dixidae : Dixa nebulosa Meigen, D. puberula Loew, D. submaculata Edwards; three Thaumaleidae: Thaumalea miki Edwards, T. pyrenaica Edwards, T. verralli Edwards ; and sixteen aquatic Empididae (Hemerodromiinae and Clinocerinae): Hemerodromia adulatoria Collin, H. baetica Collin, H. gaditana nov. spec., Wiedemannia mirousei Vaillant, W. fallaciosa (Loew), W. hygrobia (Loew), W. digitata Vaillant, W. tiburica nov. spec, Clinocera barbatula Mik, C. madicola Vaillant, C. tenella Wahlberg, C. nigra (Meigen), C. fontinalis (Haliday), C. stagnalis (Haliday), C. wesmaeli Macquart and Dolichocephala ocellata Costa. Two species are new to science and several others are recorded for the first time in Spain or Andorra, although their occurrence was expected because many records were based on collections from the French Pyrenees.

The courtship and mating behaviour of three empidid flies Empis trigramma, E. tessellata and E. opaca are described. In E. trigramma the male appears to use his complex genitalia to introduce a liquid ‘gift’ into the female's abdomen during copulation. This ‘gift’ is subsequently discharged and imbibed by the female. Such male ‘gifts’ may constitute a direct investment in their offspring, as females do not seem to acquire significant nutritional input from other sources. Males of E. opaca and E. tessellata present a ‘gift’ to the female, in the form of a dead insect, before mating takes place. Females will not mate with males which do not present a gift. Gifts presented during the period of sexual activity also appear to make a substantial contribution to female ovarian development. Some males seek to ‘cheat’ by presenting substitute gifts in the form of the fluff-bearing seeds of willows. In E. opaca such ‘cheats’ enjoyed a low rate of reproductive success, compared with males presenting food gifts. ‘Cheating’ appears to be an alternative mating tactic for males of this species.

During the summers 1992 and 1993, 15 species of Clinocerinae (Empididae) were collected on Corsica. The illustrated descriptions of six new species are given: Roederiodes wagneri sp. n., Clinocera (Kowarzia) cataractae sp. n., Wiedemannia (Chamaedipsia) ariolae sp. n., Wiedemannia (Chamaedipsia) bravonae sp. n., Wiedemannia (Philolutra) kallistes sp. n. andWiedemannia (Wiedemannia) martini sp. n.. Their systematic relations with other species are discussed. Informations is given about their geographic distribution and their habitats.

Dans les Hautes-Pyrénées, 29 espèces de Clinocerini sont signalées, dont 24 ont été décrites antérieurement. L'une des29 espèces, ainsi que 4 autres espèces nouvelles des Pyrénées-Atlantiques, sont décrites ici. Les caractères d'une espèce mal connue sont précisés.