Plants can have decreased litter leaf size and quality by fragmentation or when exposed to drought, which can affect ecosystem functioning. We evaluated the organic matter fragment size and quality on feeding preference and case construction by Phylloicus larvae, and leaf processing by microorganisms from savannah headwater streams. Containers (16 cm x 16cm x 12 cm, ~ 3L) with either Phylloicus (cases removed; n = 16) or microorganisms (n = 16) were supplied with litter from the species Inga laurina, Maprounea guianensis and Richeria grandis, cut into discs of 18.7, 13.2 and 8.1 mm size (3 sizes × 3 species = 9 discs per container). Smaller leaf discs of higher litter quality increased leaf mass loss, mainly by higher microbial activity. This likely occurs due to increased surface area to volume ratio in smaller, higher quality litter. Phylloicus exhibited preferences for fragment size only for case building, using mostly larger leaves of M. guianensis and R. grandis, likely due increased robustness for case formation. Microorganisms presented similar potential to Phylloicus for decomposing organic matter. Microbial decomposition resulted in ~20% mass loss compared to 30% in Phylloicus despite the higher invertebrate individual biomass (8% for case-building and 24% for food resource). This suggests that a decrease in leaf size after exposure to drought may lead to increased microbial decomposition. However, our results suggest that although shredders typically have low densities in savannah streams, they nonetheless play key roles in energy flow by leaf litter processing due to higher biomass.