Abstract 

The aim of this work was to determine the feeding habits of Macrostemum indistinctumlarvae using gut content analysis. The study was carried out in the stream flows into the Krasiow dam. A total of 126 larvae were captured and had the head capsule width measured. The gut content was analyzed under microscope. Seven categories of food items were determined: arthropod fragment, blue green algae, diatoms, gastropods, green algae, protozoa and rotifers. When comparing both populations in two seasons, statistically significant differences (P<0.05) were found for gastropods and protozoa. The food items, arthropods, blue green algae, diatoms, green algae and rotifers showed no difference between both populations. Macrostemum indistinctumwas found to be anomnivorous collector organism. The similarities in the seasonal trophic structure might indicate the constant availabilityof food.

Keyword: Hydropsychidae, Macrostemum indistinctum, Gut content, Feeding, Larval stage