The following aspects of Hypoaspis miles' biology were investigated ; development rate of egg to adult at different temperatures, fecundity, longevity and rate of predation on sciarids. With an increase in temperature the time taken for development decreased from 33.7 days at 15 ~ to 9.2 days at 28 ~ The threshold temperature for H. miles to complete its life cycle was between 10 ~ and 12 ~ When fed on Acarus siro, H. miles laid 2-3 eggs a day and unfertilized eoos~,, . only developed into males. Adults of H. miles (0-I day old) survived for 24.0 + 1.4 days without food and if fed for 6 days and then starved, females lived for 65.4 + 2.6 days which was significantly longer than males (45.2 + 3.0 days). With food, 60 % of males and females survived for 142 days. All larval instars of sciarids were attacked by H.miles although the numbers consumed were dependent on the size of the larvae. Egg predation was negligible and pupae were not attacked. In productivity studies of H. miles in culture (fed on A. siro), the time taken for the mites to reach a density of 45-65,000/litre ranged from 76 to 23 days at 15 ~ and 28 ~ respectively.

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Effects of some artificial substrates on the ability of the entomopathogenic nematode Steinernema feltiae to kill adult Musca domestica were studied. Replicate samples of different substrates were treated with known numbers of S. feltiae suspended in 0.25 M sucrose. Then 30 adult female flies were confined above each sample in a crystalizing basin and mortality counts were carried out 48 h later. The most effective substrates were poplin cotton, potting compost, silver sand and Fibertex SF250 horticultural capillary matting, which gave LD50 in the range of 2815 to 8912 S. feltiae. Conversely, Perlite was the least efficient material and required between 531 450 and 899 930 S. feltiae to achieve the LD50. These effects appeared to be related to the total porosity (ratio of the volume of air spaces in each material to its bulk volume) of each material, with the most efficient materials having total porosities in a median range of between 0.81 and 0.14. The significance of these observations is discussed. Les effets de certains substrats artificiels sur l’aptitude du nématode entomopathogène Steinernema feltiae à tuer les adultes de Musca domestica ont été étudiés. Des sérics d’échantillons de différents substrats ont été traitées avec des nombres connus de S. feltiae en suspension dans une solution de saccharose 0,25 M. Trente mouches femelles adultes ont été ensuite enfermées au-dessus de chaque échantillon, dans un cristallisoir, et des dénombrements de mortalité effectués 48 h plus tard. Les substrats les plus efficaces ont été la popeline de coton, le terreau de rempotage, le sable micacé et le Fibertex SF250, une natte capillaire horticole, qui ont permis d’atteindre la LD50 dans la fourchette de 2815 à 8912 S. feltiae. Par contre, la Perlite s’est révélée le matériau le moins efficace, et il a fallu entre 531 450 et 899 930 S. feltiae pour atteindre la LD50. Ces effets semblent liés à la porosité totale (rapport entre le volume des espaces remplis d’air dans chaque matériau et son volume en vrac) des matériaux, celle des plus efficaces étant située dans une fourchette médiane de 0,81 et 0,14. L’importance de ces observations est discutée.