S. Mahunka szerk.: Folia Entomologica Hungarica 28/1. (Budapest, 1975)

eggs getting onto the manure samples were not counted owing to various causes (see later) because only the final quantity of larvae was considered. That particular behaviour of house fly larvae which is responsible for the driving the larvae out of the manure when it becomes poor in nourishment was a favourable feature since the finishing of the experiment could be adjusted to this exodus. At this time the larvae were recovered from the sawdust and the manure was also searched for any remaining larvae

. The larvae were washed in Drosophila-ringer solution and made to crawl on filter paper then put in a weighed, weighing dish finally they were dried at 105 °C and weighed. In order to calculate the potentially available pig manure for the larvae, the manure granules were separated according to size: fresh pig manure with known dry matter content was weighed in a weighing dish then it was washed through sieves with meshes of 0.5x0.5 mm, then of 0.15 x 0.15 mm and throngh filter paper and the fractions were dried, weighed and compared to the initial weights. The results of larva rearings are summarized in Table 1. 1 2 3 4 5 6 g mg % 14 265 0, 6991 2,5 5.0 18928 13 92 0. 4812 5.23 5.7 7077 26.2 124 1. 1023 8.97 4.2 4732 17.1 94 0, ,7927 8.43 4.63 5496 29 389 2. ,3340 6.0 8.05 13413 35 484 2. ,7016 5.58 7.72 13828 1. Dry weight of manure sample; 2. No. of fly larvae; 3. Total dry weight of fly larvae; 4. Average weight of fly larvae; 5. Production yield; 6. No. of larvae counted for 1 kg of dry manure. Since we could examine only a small number of samples and owing to the fact that the mass rearings were started one after the other, naturally, the quality of the manure could not possibly be the same. The small number of samples nevertheless, shows that the increase in the number of larvae is directly proportional with a decrease in their weight. In mass rearing the larvae of the house fly belong to the so-called type 2, increasing number of larvae grown on identical quality and quality of manure after a certain point the weight of the larvae (pupae, imagines) begin to decrease and only after further significant increase in number (and decrease in weight) may we observe a decrease in the number of the emerging flies (cf. SULLIVAN, SOKAL, 1963). Our data show that 1 kg fresh pig manure of dry weight is an economical quantity for approximately 13 000 fly larvae. Early ecological papers treating this particular topic presented various assumptions as far as the consumed matter by fly larvae is concerned, and especially what kind of bacteria are ingested, or whether larvae may do without bacteria. Since then it was proved that the larvae need no bacteria or other microorganisms at all, though the effective nourishment intake of larvae reared in certain substrates has not been fully investigated. Using a binocular microscope the feeding of larvae was watched, it was then established that among the granules of pig manure the larvae are able