S. Mahunka szerk.: Folia Entomologica Hungarica 31/2. (Budapest, 1978)

MATERIAL AND METHODS Specimens of Sigara lateralis (Leach, 1818) were collected during 1975 in a small lake with relatively standard water-level, on an alkali-steppe near Ujszentmargita, while specimens of S. falleni (Fieber, 1848) and S. striata (Linné, 1758) on the 5th of June 1975 in a shallow puddle at Tiszafüred. Both localities are on the Great Hungarian Plain. The insects were put into 90% alcohol. The alimentary canal was dissected under dissection microscope. After mixing gently the gut contents in 1-3 drops of water (considering its quantity) the preparation was covered and investigated under microscope at 640 magnification. On the basis of previous investigations four types of gut contents could be distinguished: algae, animal body fluid, detritus and unidentified materials. The animal body fluid - as it was visible Table 1. Summary of literature data on the diet of Corixids giving no reference to the source of information Author Date Herbivores Omnivores Carnivores Weber 1930 Corixidae Horváth 1931 Corixidae Miller 1956 Almost all Corixidae Some Corixid species with palae not widening Soós 1963 Corixidae Martin 1970 Most Corixinae Jordan 1972 Corixidae Istock 1973 Several NorthAmerican Sigara and Hesperocorixa species Dosztál 1974 Sigara lateralis Cymatia coleoptrata Pajunen 1977 Arctocorisa carinata Callicorixa producta by dissecting the alimentary canal of starved specimens and those having sucked larvae of Ephemeroptera - will be precipitated by digesting enzymes and will be visible in a form of fine flakes in the preparation. Each preparation was investigated by the method of SCHILLING (BOROS, 1942). The relative frequency of the different components of food was determined by counting up their occurrence in 20 fields. This method is suitable for comparing own samples.