S. Mahunka szerk.: Folia Entomologica Hungarica 54. (Budapest, 1993)

fly pests of cattle in most of the European countries (see Papp and Garzó 1985). In addition, there is an evident demand for those kinds of methods which measure the effect of chemical control at least semi-quantitatively; these methods must be suitable to detect the change in the abundance of flies quickly and on a simple way. A wide variety of methods were proposed for this purpose: sweep netting with a fixed number of sweeps (though some people regarded it as a rather subjective method), several types of mechanical traps, Malaise-, Manitoba- or Skufin-traps unbailed or baited with CO2 or other odours. Two of those methods were applied in a cattle farm at Izsák. Data published in this paper are supplementary to the former studies in Hungary (consequently they are not to be interpreted properly without former publications), on the other hand, they serve as basis for ecological studies of higher level. Materials and Methods Imagos were collected in two cattle farms in the outskirts of Izsák at Balázs-puszta and at Mózes-major by sweep netting and by a Malaise trap on the 8th of May and on the 20th of June, 1984 (see Table 1); similar collectings were made in a sheep farm at Polgár in 1982. Cattle pat samples for rearing flies were collected on the 20th of June (8 samples) and on the 25th of September, 1984 (9 samples) (see Table 2). The Malaise trap was set up next to the stock-yard for three hours and in the meantime flies were netted from the posts and sides of the stock-yard by 100 sweeps each at 10:30 and 11:30 a.m. Imagos were collected on fresh sheep dung and on more or less fresh dung of red deer by covering the droppings with a sweeping net. The flies crawled up into the net and were drifted to its tip by some quick sweeps. Several droppings per sampling site were so covered. Rearing was made after the method of Mihályi (1965) in a laboratory at air temperature of 24±1 °C. The voucher specimens are deposited in the collection of the Zoological Department, Hungarian Natural History Museum, Budapest. Results and Discussion Data of flies captured and reared are summarized in Tables 1-3. Results on flies netted and trapped in cattle farms (Table 1, altogether for 2,633 specimens) show that 100 net sweeps are not enough to yield result in comparable numbers of imagos, or to have collected representatives of all the species present in the stock-yard. The Jaccard index (species identity) of the two samples is 6/12 = 0.5, however at least for the two dominant species (Musca autumnalis, Haematobia irritans) it gave similar results. The Malaise-trap catches specimens of the dipterous species of veterinary importance but these numbers are much deformed: the ratio of the deer flies is much higher than their true ratio on bodies of cattle and at the same time far less specimens of Musca autumnalis and Haematobia irritans were captured rather than necessary for a suitable method for evaluating the change in numbers of the population in question (e.g. for measuring the effect of a chemical control measure). In addition, Malaise trap catches so numerous other insects which is inconvenient for the original purpose. This limited number of data does not support the use of Malaise traps in evaluating chemical control of the pests of cattle. A paired comparison of samples 1 and 2, and 3 and 4, respectively show that imagos of Musca autumnalis are far more abundant in the surroundings of cattle than on the bodies of cattle (cf. Papp and Garzó 1985). The ratio in the number of the imagos of Haematobia spp. to those of Musca autumnalis is 61.5 in sample 1, 48.0 in sample 2. These ratios were found