Spider-parasite
Guides
Acrocera
small-headed flies
Acrocera is a genus of small-headed flies in the family Acroceridae. These flies are endoparasitoids of spiders, with larvae developing internally within arachnid hosts. The genus is one of the most species-rich in North America and includes regionally rare species such as A. orbiculus. Adults are rarely encountered due to their brief lifespans and elusive behavior.
Acrocera bakeri
Acrocera bakeri is a species of small-headed fly in the family Acroceridae, described by Coquillett in 1904. Species in this genus are endoparasitoids of spiders. The larvae seek out and enter spider hosts, feeding internally until mature, then exit to pupate. Acrocera is one of the most species-rich genera in Acroceridae in North America.
Acrocera subfasciata
Acrocera subfasciata is a species of small-headed fly in the family Acroceridae, first described by Westwood in 1848. The species is currently accepted as valid by GBIF, though Catalogue of Life lists it as a synonym. Like other members of its genus, it is an endoparasitoid of spiders. The species is known from the United States, with limited observational records.
Acrotaphus wiltii
Acrotaphus wiltii is an ichneumon wasp in the family Ichneumonidae. It is a specialist parasite of spiders, particularly the orb-weaver Neoscona arabesca. The female wasp locates a host spider, briefly paralyzes it with a sting, and lays a single egg on the spider's body. The larva develops as an external parasite, feeding on the living spider.
Eruga
Eruga is a genus of ichneumon wasps in the tribe Ephialtini, comprising approximately 15 species distributed across the Afrotropical, Nearctic, and Neotropical regions. Members of this genus are ectoparasitoids of spiders, specifically targeting species in the families Linyphiidae and Tetragnathidae. The genus is notable for behavioral manipulation of host spiders, inducing them to construct modified 'cocoon webs' that support and protect the wasp's pupal cocoon.
Eulonchus
North American jewelled spider flies, sapphires, emeralds
Eulonchus is a genus of small-headed flies in the family Acroceridae, comprising six described species endemic to North America. Adults are strikingly metallic blue, green, or purple, earning them the common names 'sapphires' and 'emeralds.' They are important pollinators of diverse flowering plants, with elongated mouthparts adapted for nectar feeding. Their larvae are parasitoids of spiders, specifically targeting trapdoor spiders in the families Euctenizidae and Antrodiaetidae.
Eulonchus marginatus
jewelled spider fly
Eulonchus marginatus is a species of small-headed fly in the family Acroceridae, commonly known as a jewelled spider fly. The species has a Nearctic distribution and is known to visit flowers from over ten different plant families. Like other members of the genus, adults exhibit metallic coloration and serve as pollinators, while larvae are parasitoids of spiders.
Ocnaea boharti
Ocnaea boharti is a species of small-headed fly in the family Acroceridae, described by Schlinger in 1983. The species epithet honors Richard M. Bohart (1913–2007), a prominent UC Davis entomologist who researched Strepsiptera and for whom the Bohart Museum of Entomology is named. Members of the genus Ocnaea are known as endoparasitoids of spiders, with larvae entering host bodies and consuming them from within. This species belongs to the subfamily Panopinae, one of several lineages within this morphologically unusual family of Diptera.
Ocnaea sequoia
Ocnaea sequoia is a species of small-headed fly in the family Acroceridae, described by Sabrosky in 1948. Small-headed flies are a distinctive group of Diptera characterized by their unusual head morphology and parasitic life history. The specific epithet 'sequoia' suggests a possible association with giant sequoia (Sequoiadendron giganteum) forests, though this relationship has not been explicitly documented in available sources.
Ogcodes
small-headed flies, spider flies
Ogcodes is the largest and most speciose genus in the family Acroceridae (small-headed flies), with approximately 90 described species. The genus is cosmopolitan in distribution and is the only extant genus in the subfamily Ogcodinae. All species are endoparasitoids of ground-dwelling entelegyne spiders, with larvae developing inside adult spiders before emerging to pupate.
Ogcodes eugonatus
small-headed fly
Ogcodes eugonatus is a species of small-headed flies in the family Acroceridae. The larvae are parasitoids of spiders, with documented hosts in five families: Lycosidae, Oxyopidae, Thomisidae, Salticidae, and Agelenidae. Adult morphology is characteristic of the genus Ogcodes, with a small head and rounded body form typical of Acroceridae.
Ogcodes pallidipennis
A species of small-headed fly in the family Acroceridae. Larvae are parasitic, developing within the wolf spider *Pardosa lapidicina*.