S. Mahunka szerk.: Folia Entomologica Hungarica 46/2. (Budapest, 1985)

ceptibility of the larvae to most of the hitherto applied compounds is rather higher than that of the other dipterous larvae (for data see GINGRICH and HOPKINS, 1977, SCHMIDT and KUNZ, 1980, etc.). But since these chemicals as feed-additives or in any similar applications cannot be precisely dosed in case of free keeping, the individual cattle defecate them in various concentrations even in the case of the same uptake, a monitoring of the decomposition of these compounds can hardly be executed in the everyday practice, there is no reason to suppose a concentration selective against the Haematobia larvae. The authors have found only one paper among the works on larvlcide studies extended also to the non-target populations, which is reliably accomplished,namely, SCHMIDT (1983) found in his studies on flies reared from dung of the cattle whom ivermectin i.m. had been administered, that in comparison to the control samples, an alarmingly low number, only c. 3 % of sepsid and sphaerocerid specimens each developed there. The number of Haematobia can be far more effectually reduced in the imago stage. In these control measures, the autumn spraying seems to be the most effective by eliminating the last generation of females, which produce the latest eggs in the year (e.g. sprayings from the beginning of September weakly with a non-repellent compound). In the spring the imagos of Haematobia continuously emerge, so a spraying in the spring must be less effective than one in the autumn. We can remark here that the species Stomoxys calcitrans can only be found in corrals (and, of course, in stables) in significant numbers. Its imagos could be caught on pasturing cattle only if the herd "carry out" some single specimen to the pastures; but these specimens do not propagete there

. Face fly (Musca autumnalis de Geer, 1776) This is the most abundant secretophagous species in the pastures of Hungary. Earlier investigations have proved its imagos responsible for the transmission of various diseases of cattle, among others in that of infectious bovine keratoconjunctivitis (e.g. Arends.BARTO and WRIGHT, 1982, see more in the review of PICKENS and MILLER, 1980). The life-habits of its imagos are also rather well known (PICKENS and MILLER, 1980), some recent investigations produced new data on their overwintering (CALDWELL and WRIGHT, 1981), their seasonal acitivlty, on distribution pattern on pastures (PETERSON and MEYER, PICKENS and NAFUS, 1982). Our observations complement lifehabit data, respectively, an attempt is made to evaluate synchronously the importance of the imagos and the larvae. On the basis of data in the literature a conception has developed that the releasing factors of the overwintering diapause of Musca autumnalis are a temperature lower than 16 0 C and short illumination period for the freshly emerged imagos. But according to our experiences we cannot exclude the possibility that at the beginning of autumn, it is decided already in larval stage whether the emerged imagos will develop into imagos which produce eggs or which produce Spermiums and mate, or, into imagos which on days with low temperature and short illumination period will seek for places proper for overwintering. We suppose it only, since we have reared imagos from some cattle dropping samples taken in September kept as pupae and imagos, in a laboratory of 25° C and of 18/6 photoperiod, In which the ovarioles did not begin to develop for producing eggs, respectively, which did not mate but the life-span of these imagos was similar to those prepared for overwintering (more than two months); anyway, they were confined to the "shady" places of the cages. On the basis of previous investigations, e.g. those of PAPP (1976) and other observations of Papp in corrals of horses, it became clear, that the big hoofers will trample droppings in corrals under their feet so much, that no bigger bodied fly larvae, incl. those of Musca autumnalis can develop in them. The observations and rearings from fresh, i.e. untrampled cattle dropping samples taken in corrals by the junior author in Mezohék, can prove that the females of Musca autum nalis do not lay eggs (or they do it only exceptionally) in the droppings in corrals. The small table below shows the results (in dominance of individuals) of the samples taken in Mezohék: F lies reared from cattle dropping samples collected in pastures corrals Musca autumnalis 56.97 6 0.47 Musca tempestiva 0.86 0.31 Muscid species combined 61.6 5.05 Muscids without M. autumnalis 4.63 4.48 Sepsid species combined 27.0 88.1