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§ Daily aspects | 105 aspects, and not the permanent or sub-permanent elements. The changes throw light onto the movements in the zoocoenosis, and provide clues for the studies of interactions. Finally, only an association has an aspect, the term is strictly a synbiological one, and thus it is unfortunate if used for species aspects (Balogh, 1953); the activity curves belong to idiobiology. Even if an aspect has the name of one species, this does not indicate its peak of adult activity (a larva can also be an aspect); it only means that in that period, among the numerous populations of a zoocoenosis, this is the species that is apparent, i.e. active. § THE IMPORTANCE OF SEASONAL ASPECT IN PLANT PROTECTION Precise knowledge of the aspect is important for protection, because it indicates which pests co-occur at a certain time, and what combination of methods is necessary to affect all of them. It can also provide useful information about the obstants that ought to be spared, even if they belong to catenae whose corrumpents may, currently, be latent. For example, after the flight period of the adults, the tortricid population enters a latent phase while, at this time, the egg parasitoid Trichogramma evanescens can be highly active on apple trees, and in order not to disturb its obstant activity we should not use contact insecticides. The corrumpent populations missing from the aspect had entered a latent period. The first question is: which of this latent phase, be that egg, pupa or another semaphoront group in diapause provides an opportunity for a precise census, which is a tricky methodological problem. From the relevant density (e.g. egg numbers), we can estimate the expected level of damage during the next apparent phase, and this helps pest forecasting. For this, however, we need a detailed knowledge of the aspects, as it can easily occur that an obstant element will start its activity, in full force, at a later stage than its host, as in the case of Microgaster spp. parasitising the caterpillars of Aporia crategi. It is not surprising that the aspects do not always separate sharply, because all apparent phases have a wave-like shape, starting with a few early individuals, and ending with a few late ones, plateauing somewhere in between. This plateau characterises the aspect; plant protection measures are best implemented before this point. § THE QUESTION OF PERMANENT SPECIES REPRESENTATION After seeing the various dynamic events, overlapping each other, and dependent on weather, time of day and season, we can rightfully ask: can we talk about stability at all, about communities of constant species composition?
