Do leaf shelters always protect caterpillars from invertebrate predators?

1. All larval instars of Epargyreus clarus, the silver‐spotted skipper, construct and inhabit leaf shelters that are presumed to protect them from predator attack. 2. Shelters effectively protected the larvae against foraging Crematogaster opuntiae ants and naive Polistes spp. wasps in laboratory tests, but did not protect them from predators, largely vespid wasps, present in the field. 3. A range of factors, including type of predator, learning ability, and experience level, may determine the effectiveness of leaf shelters as protection from predators.