S. Mahunka szerk.: Folia Entomologica Hungarica 50. (Budapest, 1989)

mens were counted on Lemna as on Hydrocharis, in the experiment 1. 89 times. This conformity is remarkable despite that the density of the specimens in the experiment was much higher (3.96 specimens per 100 square centimeters* than in the field, a density which can also be responsible for the occurrence of specimens on the (small) open water surface. It can be added that in the same arrangement of plants Microvella specimens showed a more expressed preference sequence preferring water to Lemna and Lemna to Hydrocharis (data will be published elsewhere*, also in agreement with field observations. These results confirmed the assumption that the floating net is a prospective equipment suitable for density estimations and microhabitat preference investigations, and that these small semiaquatic bugs do show preference for the surface they are resting or praying on. Fig. 2: Scheme of the experimental arrangements of floating plants REFERENCES ANDERSEN, N.M. (1982*: The semiaquatic bugs (Hemiptera. Gerromorpha*. Phylogeny, Adaptations, Biogeography and Classification. - Entomonograph 3: 1-455. BAKONYI, G. and VÁSÁRHELYI, T. (1987* : Investigation on the aquatic and semiaquatic bugs of the Lake Balaton 'in Hungarian). - Proceedings, XXIX. Hidrobiológus Napok, Tihany. 1K7