Eye flies

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Eye flies
Eye flies when mating

Eye flies when mating

Systematics
Class : Insects (Insecta)
Order : Fly (Diptera)
Subordination : Flies (Brachycera)
Partial order : Muscomorpha
Superfamily : Syrphoidea
Family : Eye flies
Scientific name
Pipunculidae
Walker , 1834
Subfamilies
  • Chalarinae
  • Nephrocerinae
  • Pipunculinae
Eye flies on the wedding flight

The eye flies (Pipunculidae) are a family of the two-winged (Diptera). Here they are counted among the flies (Brachycera); they are most closely related to the hover flies (Syrphidae). Around 1380 species of this group are known worldwide; around 110 species are given for Germany. Most species are parasitoids of cicadas , only the eyes fly of the genus Nephrocerus parasitize gnats (Tipulidae).

The flies are mostly hairless and dark in color. The greatly enlarged, almost spherical compound eyes , which probably serve primarily to locate the host animals for larval development, are striking . The long, narrow wings are also typical. The saber-shaped ovipositor of the females is also well developed. The flies feed almost exclusively on the honeydew of their hosts.

Reproduction

The copulation of the eye flies takes place in flight, with the male grasping the female and holding onto the legs. This clamp prevents the female from flying, which then lifts the abdomen up. The couple then settles on a leaf or other parts of the plant, with only the female standing on the base. The almost 40-minute pairing is ended again in flight. In order to lay eggs, the females usually slowly fly off the vegetation near watercourses, looking for a host for their larvae. These are exclusively cicadas, with some species using very specific groups of species or even individual host species. The host is packed and in flight is covered with an egg by puncturing the egg-laying apparatus. The larva then develops in this host, which usually only leaves when it is fully developed. Some species, such as Verrallia aucta, infect the adult stage directly, in this case the meadow-foam cicada Philaenus spumarius and the grass- foam cicada Neophilaenus lineatus , whose larvae are protected by a foam coat .

Effects on the host

If younger host larvae are attacked, the genital organs do not develop in whole or in part ("parasitic castration"). In older hosts that are still reaching adulthood, only the internal sexual organs are reduced. The earlier the host is attacked, the more pronounced the effects of parasitization are, and this leads to the host being castrated. Older parasite larvae (2nd larval stage) bore themselves out of the cicada, mostly in the border area of ​​the chest ( thorax ) and abdomen ( abdomen ), fall to the ground and pupate there. The host dies shortly beforehand, but can remain anchored to the host plant with its stinging bristles and is then quite noticeable due to the laterally bent, hollowed-out abdomen. Younger ophthalmic fly larvae remain endoparasitic in their host's abdomen.

Larval development

The breathing of the larva is ensured by a front and a rear breathing hole ( stigma ) of the tracheal system (amphipneustic), possibly also a coupling to the trachea of ​​the host animal. They develop in the host's abdomen and have only two larval stages; pupation usually only takes place outside the host in the litter, often in the riverside of rivers. When the imago hatches, a dorsal and a ventral cover are blown off the pupa shell. The overwintering takes place either as a pupa or as a larva in the overwintering host. Some species, such as Cephalops semifumosus, have two generations a year.

The number of generations of the eye flies is mostly based on that of their cicada hosts. These predominantly form one to two generations per year (univolt or bivolt). Only 2 species ( Eudorylas subterminalis and Pipunculus campestris ) have 3 generations per year in Central Europe. These parasitize on around 10 different species of small cicadas . The overwintering usually takes place in the pupal stage in the ground. In the case of cicadas that overwinter as larvae, the eye flies remain in the host as young larvae, only to complete their larval development in spring.

Types (selection)

Fossil evidence

Fossil members of this family are very rare and so far only known from various amber deposits. The oldest evidence goes back to an inclusion in the Upper Cretaceous Canadian amber. Most of the finds come from Eocene Baltic amber , some from the somewhat younger Mexican and Dominican amber .

literature

  • RL Coe: Diptera family Pipunculidae. Handb Ident British Insects 10 (2c), London 1966.
  • K. Honomichl, H. Bellmann: Biology and ecology of the insects. + CD-Rom. Gustav Fischer Verlag, Stuttgart 1994.
  • R. Remane, E. Wachmann: Cicadas - get to know, observe. Naturbuch Verlag, Augsburg 1993, ISBN 3-89440-044-7 .
  • N. Waloff, MA Jervis: Communities of parasitoids associated with leafhoppers and planthoppers in Europe. In: Adv Ecol Rs. 17, 1987, pp. 282-403.

Web links

Commons : Pipunculidae  - collection of images, videos and audio files

Individual evidence

  1. ↑ George O. Poinar, Jr .: Life in Amber. Stanford University Press, Stanford (Cal.) 1992.