The feeding habits of Agrypnia pagetana Curtis and Phryganea grandis L. in the rockweed-belt in the northern part of the Baltic have been investigated. The fore-guts of larvae, collected every month, except during the flight period have been analysed. The main part of the food of Agrypnia pagetana consisted of filamentous algae and fragments of Fucus vesiculosus. Phryganea grandis consumes mainly Arthropods e.g. Idotea spp. and Chironomus spp. No special difference in food choice between different seasons has been stated. The larvae consume the most accessible food. Different larval instars consume the same sort of food, but of different size. The larvae feed most actively during the autumn and in this period they also grow most and in the spring before the pupation. During the winter the fore-guts contain much less food than in the autumn.