Acrocerid

Acrocerid is a family of small to medium-sized flies belonging to the order Diptera. These flies are also commonly known as "owl flies" or "hooded-eyed flies" due to the characteristic large, often globular, eyes that can meet dorsally. Acrocerids are endoparasitoids, meaning their larvae develop inside a living host. The hosts are typically large, slow-moving arthropods, with spiders and harvestmen being the most common. Adult acrocerids are generally short-lived and do not feed, relying on reserves built up during the larval stage. They are found worldwide in a variety of habitats, though their cryptic nature and the rarity of observing their life cycle make them less commonly encountered than many other fly families. The larvae are characterized by a mobile, predatory first instar that seeks out a suitable host. Once a host is found, the larva enters and undergoes several molts, developing into a plumper, less mobile form that consumes the host's tissues. The taxonomy of the Acroceridae is complex, with several subfamilies and genera described. Despite their specialized parasitic lifestyle, they play a role in regulating populations of their hosts in their respective ecosystems.