Stylogaster

Macquart, 1835

thick-headed fly, needle-tailed fly

Species Guides

3

Stylogaster is a of conopid flies distinguished by extreme morphological and biological specializations. possess an elongated exceeding body length when extended, and females have a dramatically elongated folded beneath the body—the 'needle tail' referenced in the generic name. The genus is the sole member of Stylogastrinae and comprises approximately 92 with predominant Neotropical distribution. Unlike other conopids that parasitize Hymenoptera, Stylogaster species are endoparasitoids of orthopteroid insects (crickets, ) with documented associations also including various calyptrate Diptera.

Stylogaster neglecta by (c) skitterbug, some rights reserved (CC BY), uploaded by skitterbug. Used under a CC-BY license.Stylogaster neglecta by (c) skitterbug, some rights reserved (CC BY), uploaded by skitterbug. Used under a CC-BY license.Stylogaster neglecta (Michael Hodge) by Michael Hodge. Used under a CC BY 2.0 license.

Pronunciation

How to pronounce Stylogaster: /ˌstaɪloʊˈɡæstər/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Distinguished from all other Conopidae by the combination of: extremely elongated longer than body when fully extended; reduced anal in wing venation; and in females, the greatly elongated folded ventrally beneath the body. Antennal proportions differ between —S. neglecta has short 2nd antennomere and highly elongate 3rd antennomere, while S. biannulata has 2nd and 3rd antennomeres nearly equal in length. are uniquely morphologized with rigid barbed tips, unlike the smooth eggs of other conopids.

Images

Habitat

Associated with supporting army ant (Ecitoninae, Dorylinae) raiding columns in Neotropics and Old World tropics, where females exploit -driven prey disturbance. occasionally found at flowers. habitats include ground-dwelling Orthoptera and environments.

Distribution

Widespread across tropical and subtropical regions: Neotropics (69 , predominant center of diversity), Afrotropical region including Madagascar (14 species, with 5 to Madagascar), Australian region (5 species), Oriental region (2 species), and Nearctic region (2 species: S. neglecta and S. biannulata). Absent from Palaearctic region. In North America, recorded from southern Ontario and northeastern United States southward.

Diet

feed on nectar using the elongated . Larvae are endoparasitoids developing within insects.

Host Associations

  • Oecanthus nigricornis - confirmed black-horned tree cricket; first confirmed of S. neglecta with successful larval
  • Muscidae (various genera) - carrier or including Dichaetomyia, Helina, Phaonia, Stomoxys; attached to but definitive status unconfirmed
  • Calliphoridae - carrier or including Bengalia, Tricyclea, Hemigymnochaeta; 24% of Tricyclea specimens in one study bore Stylogaster
  • Cockroaches - reported historical records, specific not consistently documented
  • Army ants (Ecitoninae, Dorylinae) - ecological associatefemales exploit raiding columns to access flushed prey; not obligate for all as occurs in Madagascar where army ants are absent

Life Cycle

are forcibly jabbed into using the female's elongated ovipositor; barbed egg tips anchor in host tissue. approximately 30 days based on S. neglecta rearing data. Larvae develop as endoparasitoids, eventually emerging to pupate; host death follows larval . Multiple has been documented.

Behavior

Females exhibit specialized oviposition : hovering over army ant raiding columns, then diving to jab into prey insects flushed by activity. This high-risk strategy results in significant egg loss when ants capture post-oviposition. Oviposition involves a stabbing motion with the ovipositor thrust forward between the legs. Some may operate independently of army ants.

Ecological Role

Endoparasitoid of orthopteroid insects and potentially other Diptera. May function as agent through of calyptrate flies. Association with army ants represents a complex three- interaction exploiting -driven prey disturbance.

Similar Taxa

  • Other ConopidaeOther conopid parasitize Hymenoptera (, bees, ants) rather than orthopteroids; lack the elongated and needle-like female ; have smooth without barbed tips
  • Mydidae (mydas flies)Large size and -mimicry in some may cause confusion; distinguished by elongate clubbed versus short antennae of Stylogaster

Tags

Sources and further reading