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WILLY MATTHEY 



The depth of the water exerts a sélective effect on the insects according to 

 their size and their mobility. 



When there is much insolation, the mud deposits rise and accumulate at 

 the surface. Larvae of the smaller species are abundant here. Aquatic and 

 surface predators find sufficient food since consumers I are fréquent in thèse 

 stations. 



10. Herbaceous végétation in the ponds and along the banks of the channels is 

 necessary for egg-laying of several species. lt facilitâtes metamorphosis of 

 Odonata. Along the banks, the leaves bending towards the water make 

 refuges for numerous larval forms. 



In the channels, bladderwort and filamentous algae support the microfauna 

 and those species which do not swim easily in deep water. This végétation 

 serves as food for tadpoles. 



11. One can distinguish deep channels, shallow channels and a combination of 

 both, so called mixed channels. The latter contain most species since they 

 include both deep and shallow water species. 



Frogs ( Rana temporaria ) lay their eggs in the mixed channels. 

 It is possible to observe zones along the banks of thèse channels determined 

 by the degree of imbibition of the peat (Dolichopodid zone, Carab and 

 Saldula zones). 



In the high bog, the ponds in the centre are deeper than those of the NW and 

 SW parts of the bog, and their fauna is also richer. 



12. Development cycles of the insects can be divided into four catégories: 



1. A single génération per year; the adults hibernate. 



2. A single génération per year; the eggs and the larvae hibernate. 



3. Two générations per year. 



4. A single génération every two years. 



13. The author has studied the influence of ecological factors on insect repro- 

 duction and on larval survival. 



Snow acts as a protection for hibernating species. 



The rate of development of the eggs and larvae is determined by the tem- 

 pérature. The latter also influences the behaviour of certain species (Hydro- 

 philids). 



Insolation is bound to the température but it also has its individual effect. 

 It détermines, for instance, the time of flight and the migration of aquatic 

 species and also the surface activities of the high bog carabs. 

 Médium of strong winds force the large anisopterans to land, thus preventing 

 them from feeding and breeding. The effect of the winds on smaller winged 

 insects which occupy the herbaceous, arbustive and pine-tree levels, is slight. 



