Food habits and dietary overlap of perlid stoneflies (Plecoptera) in a tributary of Lake Ontario
Food habit studies were conducted on the nymphs of three species of sympatric perlid stoneflies from May to September 1979 in Orwell Brook, New York. A total of 1106 specimens were examined, which included 744 Phasganophora capitata, 251 Paragnetina immarginata, and 111 Acroneuria abnormis. Chironomids, trichopterans, and ephemeropterans were generally the principal, prey of all three species. Using Horn's measure of overlap, the monthly diets of P. immarginata and P. capitata were most similar [Formula: see text] and the diets of A. abnormis and P. immarginata[Formula: see text] least similar. Diel trends in food consumption during July indicated that the feeding intensity of both P. immarginata and P. capitata was the greatest from 2100 to 0500 hours. Examination of the guts of P. immarginata and P. capitata at 4-h intervals over a 24-h period showed that there was considerable variation in the diel diet composition of these species.