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

Admitting the merits of the experiments a strong counter-argument may also be formulated to attack the partial consumption of chicken manure by house fly larvae, that is, it is far more advantageous to feed desiccated chicken manure to ruminants, perhaps also to pigs than to obtain pupae though highly valuable but of small production yield. Under natural conditions house fly develops primarily in pig manure and several authors (among them LORINCZ, MAKARA, 1934) proved that they develop there in great masses. This is why I decided to carry out orientative investigations to establish the production yield of house fly larvae on the most natural substrate, i.e. rearing themonpig manure. Besides, during the investigations I made some ecological observations. I thought it might be profitable to study whether it is not more advantageous to gain larvae as the final product since it had been common knowledge not only in Diptera but in other insects orders too that from the end of the last instar stage to the emergence of the adults a significant decrease in weight takes place in the animal (e.g. HAUB, 1938). Fig. 1. A: The maintenance of the breeding stock; B: the rearing of larvae (1: material feeding the imagines, 2: pig manure of known weight and of known dry content, 3: sawdust) Our breeding stock was built up from the offsprings of one female reared at 30 °C from the substrate of a calf-grid on the 6th of June, 1973. In all my subsequent experiments I used the eggs of this breeding stock, independent from the maintenance of the breeding stock, I carried out also the production experiments though the stock was similarly reared in thermostat at 30 + 0.2 °C . The pupae originating from the breeding stock were placed in a glass container (Fig. 1) which was covered by a net with a mesh of 1. 5 x 1. 5 mm

. The nourishment and the manure to be ingested were placed under the container. The flies were fed with both sugared or non-sugared skimmed milk, syrups of flucose or sucrose, bread soaked in milk and with fresh pig manure. The newly hatched flies need some kind of a protein source tobe able to lay a sufficient number of eggs, though with non-sugared skimmed milk (milk powder) or fresh pig manure changed daily are also good enough for the flies to produce the maximum number of eggs. The manure sample infested by fly eggs, the weight and water content of which had previously been determined was placed at a temperature of 30 + 0, 2 °C according to the scheme depicted in Fig. IB. The thickness of the fresh pig manure was between 2 and 6 cm, this did not influence production. The