Pamphiliidae

Pamphiliidae (sometimes incorrectly spelled Pamphilidae) is a small wasp family within Symphyta, containing some 200 species from the temperate regions of North America and Eurasia. The larvae feed on plants (often conifers), using silk to build webs or tents, or to roll leaves into tubes in which they feed, thus earning them the common names leaf-rolling sawflies or web-spinning sawflies. Some species are gregarious and the larvae live in large groups. Fossils of Pamphiliidae have been dated to the Jurassic period. Read more at Wikipedia