Achias rothschildi

This stalk-eyed fly (Achias rothschildi) belongs to the family Platystomatidae and is a highly localised species endemic to Papua New Guinea.

The eye-stalks are mainly used for display in confrontations with other males as they try to establish territory in order to attract a mate. 

During conflict between males

  • the two individuals involved face each other, the central parts of their heads touching
  • combat begins - each male using his front legs to strike out at his opponent 
  • eventually one of the males backs down
    • usually the one with shorter eye-stalks seems to be instinctively submissive in conflicts

Species detail

Eye stalks 

eye stalks

The males have long eye-stalks, which vary in size so that the distance between the eyes ranges from about 20 to 55mm. The holotype of this species has the widest head of any known fly.

 

  • are lateral extensions of the fly's head
  • eyes are positioned on the end of each stalk
  • long eye-stalks are only found on males
    • varying in length between individuals
  •  females have very short eye-stalks.
  • sometimes referred to as "pedunculate eyed".
  • Achias rothchildi
    Taxonomy

    Achias rothchildi is one of a genus containing nearly 100 described species, most of them endemic to New Guinea. Get a further taxxonomic description ofthis species.

  • A tropical rainforest in Papua New Guinea.
    Distribution habitat and conservation

    Achias rothchildi is endemic to Papua New Guinea. Find out about the types of habitat this species is known from.

  • achias-rothchildi-3
    Biology

    The largest males have the widest head of any known fly. Learn about the size and growth patterns of Achias rothchildi.

  • A long eye-stalk of the male Achias rothschildi.
    Behaviour

    Studies of stalk-eyed flies suggest that individuals with longer eye-stalks are more successful in conflicts between males, and therefore have an advantage when establishing territory. Discover more about the behaviour of this species.

  • Achias rothchild
    References

    Get reference material for Achias rothchildi.

Images

Achias rothchildi

A mounted specimen of the Achias rothchildi stalk-eyed fly held at the  Museum.

Achias rothchildi wing

A close up of the wing of Achias rothchildi,a stalk-eyed fly from Papua New Guinea.

A tropical rainforest in Papua New Guinea

A tropical rainforest in Papua New Guinea.

Achias rothchildi body

Achias rothchildi with a body length of 13.5 -16 mm and a wing length of 14 -16.5 mm.

A long eye-stalk of the male Achias rothschildi

A long eye-stalk of the male Achias rothschildi . The eye-stalks are mainly used for display in confrontations with other males as they try to establish territory in order to attract a mate. The eye stalks vary in length between individuals - those with longer stalks tend to be more dominant.

Author

Nigel Wyatt

Curator of Diptera, Department of Entomology.

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