Dr. Murai Éva szerk.: Parasitologia Hungarica 25. (Budapest, 1992)

Mihályi (1966) made his collectings with human faeces in or in the surroundings of 42 localities in Hungary, collecting 9,779 dipterous specimens in 149 samples. Our 29 samples from 4 localities in 3 years contain 9,191 specimens. Mihályi's exposition time was 1 hour, less frequently 2 hours, ours was 3 hours (and mostly 4 hours in 1988). It is obvious that this is the main reason for his smaller samples. However, traps baited with human faeces do not catch twice as many flies during twice as much time (see e.g. Mihályi 1966). His trap hours cannot be determined precisely (the numbers in his table with 180 trapping hours with faeces (Mihályi 1967) are surely erroneous, when one makes a counting in his theses; that number is higher for sure). In any case, it is quite certain that we collected much more flies per time unit during our about 90 trapping hours than Mihályi did three decades ago. He collected representatives of cca 200 to 225 dipterous species (incl. the "indet." species), our samples contain about 175 to 180 species, i.e. about 80% of the former value. This is again comparatively higher. We are not unaware that the legitimacy of such a comparison is limited or even questionable. Mihályi exposed his traps also in yards of villages, on meadows etc. Traps exposed in settlements are likely to collect less specimens and species than those in forests but meadows offer a richer fauna and more abundant populations than do forests. So our general conclusion is limited to an assertion that loud and repeated statements on the loss in the diversity of insects in the last decades cannot be proved for the forest flies visiting faeces (quite the same applies to forest drosophilids). Considering that our data are not fully comparable to Mihályi's, we selected three groups of flies to make comparison in the number of species, namely family Sphaeroceridae ("lesser dung flies"), family Fanniidae, and family Muscidae. The sphaerocerid materials from Mihályi's collectings were identified and published by Aradi (1965). Since all those specimens are still preserved in the collection of the Hungarian Natural History Museum, all the identifications are controllable even today. He reported 31 species but all the specimens of 2 species (Opalimosina pullula and Coproicapseudolugubris) were misidentified so we can count on 29 species. We collected representatives of 28 sphaerocerid species. Mihályi's material included 12 species which were not collected now, among them 6 species of dung heaps, barns and stables and of village yards, however, since these 6 species also occur in the wild nature, they are not left out of our consideration. We collected representatives of 11 species, which were not caught by Mihályi. The full combined list contains 40 species. Thus the Jaccard index of the two series of collectings is 17/40 = 0.425. Our final conclusion is that none of the two series produced representative results for the species of Sphaeroceridae visiting human faeces in Hungary. As for our series, we probably must not expect such a representativeness. But if we take into consideration that his 149 samples collected in various habitats are not enough to be representative, we must probably revaluate former statements on the level and quality of knowledge on faunas based on specimens from collectings of a few years. As for the number of specimens, our samples are smaller; this is no surprise for reasons easily accounted for: sphaerocerid populations are bigger, their abundance is much higher near dung heaps, village yards and on wet meadows than those of the species in mountain creek valleys.