Traditionally, freshwater ecologists have assumed that species interactions, larval resources and environmental stressors in the aquatic environment influence the structure of aquatic insect communities, and that community composition is a product of how these processes play out over multiple generations. However, taxa with complex life cycles may be strongly influenced by processes that drive recruitment success (the addition of new individuals to a population). This may be pronounced for taxa with short life spans and a dispersive life stage that can move among communities. Aquatic insects are good examples with short-lived adults that disperse terrestrially across landscapes and then lay eggs in water bodies, which are inhabited by the longer-lived juveniles. Tests of recruitment limitation are exceedingly rare for aquatic insects, despite being common in other ecosystems occupied by species with complex life cycles. For a guild of stream-dwelling caddisflies that oviposit exclusively on emergent rocks, we tested whether recruitment was limited by the supply of dispersive adults, resource availability (oviposition sites), or both. In multiple locations on multiple rivers with overlapping but distinct species composition, we simultaneously surveyed abundances of adults, oviposition sites and egg masses, the latter being a yardstick of recruitment success. In a guild of eight species, three appeared to be limited by adult supply only, three by resource abundance only, one by both processes in equal magnitude, and one by neither. There were no correlations between numbers of oviposition sites and adult females, suggesting these mechanisms operate independently. Our results are consistent with the notion that recruitment limitation may influence populations and that the limitation mechanism can vary among species that share common oviposition behaviours. Terrestrial processes affecting adult movement and the supply of adults at oviposition sites may lead to species-specific, temporal and spatial fluctuations in population sizes and thus fluctuations in community composition.