Plastic trash is a growing ecological concern. Rivers can accumulate anthropogenic litter, including plastics, which are slow to breakdown and can potentially alter freshwater ecosystems, but there is limited information on the ecological effects of plastic pollution in freshwaters. In temperate forested streams, leaf litter is a key component of stream food webs. Plastics can act as alternate substrates for biofilm growth. Increasing plastic litter in streams may result in shifts to detritivorous food webs, altering biodiversity and ecosystem functioning. Plastic trash can be highly variable. Different plastics are composed of different polymers and can be different colors and textures, which impacts factors including light transparency, biofilm growth and colonization, which could alter community structure. We examined changes in both the mass of plastics and diversity of macroinvertebrate colonizers on plastic bags following a 2-week incubation period in July, 2024 in a central Pennsylvanian forested stream. Plastic bags were placed along a 100m stretch of the stream following standard methods for leaf packs, substituting strips of plastic for leaves. Five plastic types including Ziploc bags (clear, LDPE), trash bags (black, (LLDPE) and white single-use shopping bags (white, HDPE), as well as biodegradable bags (cornstarch-based) along with a mixed bag treatment of all plastic types were examined, with 3 replicates of 30 g of each plastic bag. There were significant differences in both macroinvertebrate diversity and plastic mass after incubation. White HDPE bags had the largest increase in mass (13 ± 5g) and visibly had more biofilm growth compared to other types, whereas the compostable bags decreased in biomass (-2.7g ± 0.9g). Chironomid larvae, followed by caddisfly larvae (Philopotamidae) were the most abundant taxa colonizing most plastic bags, with significant differences in diversity and richness observed among plastic bag types. Plastic pollution will alter aquatic ecosystems, differences in the composition of that plastic trash may also result in changes.