Conopidae, commonly known as thick-headed flies, is a family of acalyptrate ⓘ Diptera comprising several hundred species worldwide, most diverse in warm temperate and tropical regions. Adults are medium-sized flies with a characteristically bulbous head, large eyes, and short antennae. Many species show striking wasp-like mimicry, with elongated abdomens, narrow waists, and bold black, yellow, or reddish markings.

Conopids are best known for their highly specialised parasitoid ⓘ life cycle. Females lay eggs directly into adult bees or wasps, often intercepting them in flight or on flowers. The larva develops internally, eventually killing its host. Adults, however, are harmless nectar feeders and are frequently seen visiting flowers in open habitats such as grassland, heath, and woodland edges. This combination of floral visitation and parasitoid behaviour gives Conopidae a distinctive ecological role among flies.