S. Mahunka szerk.: Folia Entomologica Hungarica 28/1. (Budapest, 1975)
Since our results are based on only a small number of repetitions their conclusive value is naturally smaller still even these values seem to prove that it is not economic to feed pig manure to fly larvae. It is found on the basis of particle size that at most only 40 % of the dry weight of manure can be taken up by the larvae. Under laboratory conditions it is possible to continually obtain larvae corresponding to 10 % of dry weight of manure (our results at 30 °C show 8.05 % maximum production, which might be somewhat higher at a lower temperature), but the same under industrial circumstances seems rather improbable . The larvae after reaching their final maximum weight begin to lose weight until the pupal phase when they are suitable for troring, which attains a value of some 20 % of their total weight, and although the loss is the result of fat oxidation still it appears to be more economic to obtain larvae as the final product. This is supported by the fact that the manure charged with the near maximum number of eggs up to a certain limit the degree of pupation - i.e. the possibility of pupa production - decreases, and the larvae indicate when leaving the manure that the manure is no longer suitable for further breeding because they consumed the nourishing parts of it. Even if 10 % production seems economic still we have to consider whether a microbiological method would not be more suitable, and even cheaper, since there are preliminary investigations with good results (ZAJCEV et al. 1972). There are two major problems involved in the mass production of larvae: 1. In modern large agricultural concerns the floor is washed by water-jet, thus, the water-content of the available manure is very high. In this kind of manure fly larvae cannot develop (TEOTIA, MILLER 1970a found the limiting value for water content to be 80 % in the case of chicken manure, the same is only slightly higher for pig manure, cf. PAPP 1974), or only when the manure is spread in a centimetre thickness. In solid manure the larvae may burrow down 15 cm deep because the burrows conduct oxygen down to the lower regions, too. 2. To maintain continous breeding a basic stock is needed that is to be provided for independently of the mass production. This means the feeding of a huge number of flies that is to be kept under safe, optimal conditions since we may calculate 10 eggs a day per one female house fly. + According to our results the breeding of approximately 13 000 fly larvae from 1 kg pig manure calculated for dry weight is economic. 16 000 eggs are needed to obtain 12 000 larvae if one considers the hazards and only 25 % loss, calculated for 1 kg of pig manure of dry weight. This means that to have such a number of eggs per day we would need at least 1600 females and as many males, i.e. 3200 individuals. (MÜLLER' s (1969)data disclose about the same values, according to him 3 g of fly eggs are needed for 4000 g fresh chicken manure. ) Considering the huge amount of pig manure cleared off day by day from a large-scale pig farm it would need a vast number of flies just to maintain the One batch of eggs contains about 100-150 eggs (an average of 120; our investigations resulted two extremes 90 and 162), a fly lays 4-6 such batches of eggs in about every two weeks. The female house flies of out breeding stock at 30 C°laid at most two batches of eggs and they lived for about three weeks, only in exceptional cases was their life-span longer. At lower temperature the life-span is longer and we may except more eggs too, but this fact does not influence the 10 eggs per day average. Egg production is uniform if we work with a huge number of "asynchronic" females.
