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

It was rather striking to find that the dry weight of the breeding sample weighed after the larvae have left them decrease so little compared to the original fresh weight that it was not more than three times the total dry weight of the produced fly larvae! TABLE 2. The proportion of the various particle sizes of pig manure The smallest diameter of particles manure samples >0, 5

2 mm

2 0.15

2 - 0.52 mm

2 58.9 3.8 54.1 53.9 5.1 caught by filter 14.6 21.2 paper > 45.9 filtering through 22.6 19.7 We have also investigated the weight conditions of the variaous developmentafr-phases, starting from the larva with final maximum weight to the emergence of the imagines. During the maintenance of the breeding stock the live weight of the larvae with final weight, pupae and emerging imagines was measured by using 50-100 specimens at a time, whose average weight was given."

1

" The averages of two independent series of measurements are plotted in Fig. 3. It is clearly seen that the weight of the imagines is significantly smaller than that of the larvae with final weight (52. 7 % and 50.0 %). In the beginning the curve shows a strong decrease in weight since the larvae with final weight do not feed any more and empty their intestines, furthermore, when searching for a suitable site for pupation the muscle action consumes much energy; when the pupa has formed the weight desrease slows drown, but before emergence it is speeded up again. The pupal case represents a large amount of matter, this appears on the curve somewhat deformed since its dry matter content was weighed to be 63.45 % and 66.7 %, what is twice more the dry weight of the imago. For comparative purposes we also give HAUB' s (1938) mean values obtained from Phormia regina MEIG. (Calliphoridae). The course of the curves is so similar that we venture to assume that this phenomenon is valid for wider systematic groups. The above findings have a theoretival value that in this light many production data refferring to fly production obtained by weighing the adults should be corrected (incl. PAPP, 1971). In order to give an answer which phase of ontogeny is the most economic for obtaining live-matter mass we not only have to consider the weight conditions but also the chemical composition of the larvae and pupae in the individual ontogenetic phase. The investigation of larvae with final weight shows that they contain 93.66 % organic matter, 55.33 % carbon and 7.15 % nitrogen (i.e. 44.68 % raw protein) calculated for dry weight Basis for comparison is offered by the fact that the water-content of the fully developed larvae and newly hatched adults is almost identical (cf. Fig. 3), and that of the pupae is but slightly higher (cf. Haub, 1938).