Euroleon nostras

Euroleon nostras is a species of antlion found over most of Europe.[1] The scientific name can be translated as "our European [ant] lion".[2] Adults resemble dragonflies or damselflies and may reach up to 30 mm (1.2 in) long, with a wingspan of 70 mm (2.8 in). The larvae prey on ants and other small creatures and require dry sandy soil in which to dig their pitfall traps.

Euroleon nostras
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Neuroptera
Family: Myrmeleontidae
Genus: Euroleon
Species:
E. nostras
Binomial name
Euroleon nostras
(Fourcroy, 1785)

Description

The larva of E. nostras has large jaws and a broad abdomen. When fully developed, which may take two years, it pupates under the soil, undergoes metamorphosis, emerging a month later as a much larger winged insect. The adult E. nostras is brown and resembles a dragonfly or damselfly in appearance. It is about 30 mm (1.2 in) long with a wingspan of about 70 mm (2.8 in). The four large translucent wings are spotted with brown.[3]

Distribution

Euroleon nostras has a widespread distribution in Europe, and has been recorded from almost all European countries, its range extending from Spain through Germany to western Russia. It is also known from Morocco in North Africa, and from Turkey, Armenia, Georgia and Azerbaijan in Asia.[4] It is an extremely rare insect in Britain, known only from the Minsmere area of the Suffolk coast and Holkham National Nature Reserve in Norfolk.[5]

Behaviour

The larva of E. nostras excavates a conical pit-trap in sand or loose soil and then semi-buries itself at the bottom. It is able to detect the approach of potential prey by detecting vibrations in the ground. It can locate where the prey is at any given time and can flick loose sand with its head accurately towards it.[6] Small arthropods that inadvertently enter the trap are unable to climb out because of the loose surface and are pounced on by the ant-lion larva, which then sucks out their body fluids before tossing out the dry husk. The larvae favoured locations with dry sand under a rock overhang or other surface that prevented direct rainfall. In a research study in Slovenia, the density of the pits varied from 44 to 543 pits per square metre. Later instar larvae required more space for their larger pits. In conditions of overcrowding, cannibalism took place. In an experiment where the larvae were stocked at 1000 per square metre, about half were killed and eaten by other larvae.[7]

Adult E. nostras are on the wing from June to September but are seldom seen because they are nocturnal, hiding during the day in vegetation. The short adult life is devoted to reproduction. The female hangs on a twig when mating and the male attaches himself to her by his reproductive organs and dangles below for the hour or two that mating takes. After this, the female flies to the ground, tapping it with her abdomen to find a suitable spot, and inserting her ovipositor into the sand and laying an egg. She repeats these actions about twenty times. While on the ground, she is in danger from antlion larvae.[8]


  • Lateral view
  • Frontal view
  • Larvae
  • Pit-trap


References
  1. Niels Schulz. "Ameisenjungfer" (in German). natur-lexikon.com.
  2. Kwizera, Charles (5 March 2010). "Wildlife Discovery: The Antlions". The New Times. Retrieved 24 February 2016.
  3. "Suffolk ant-lion (Euroleon nostras)". ARKive. Archived from the original on 2008-10-10. Retrieved 2007-02-06.
  4. Canbulat, Savaş (2007). "On the occurrence of Euroleon nostras (Fourcroy, 1785) in the Turkish ant-lion fauna (Neuroptera, Myrmeleontidae)" (PDF). Boletín Sociedad Entomológica Aragonesa. 40: 232.
  5. "Antlion larvae colony thriving at Norfolk reserve". BBC Norfolk. 17 October 2011. Retrieved 29 July 2014.
  6. Mencinger-Vračko, Bojana; Devetak, Dušan (2008). "Orientation of the pit-building antlion larva Euroleon (Neuroptera, Myrmeleontidae) to the direction of substrate vibrations caused by prey". Zoology. 111 (1): 2–8. doi:10.1016/j.zool.2007.05.002.
  7. Devetac, D. (2001). "Competition in larvae of two European ant-lion species (Neuroptera: Myrmeleontidae)". Journal of Neuropterology. 3: 51–60. ISSN 1029-2020.
  8. Swanson, Mark. "Reproductive behaviour". The Antlion Pit. Retrieved 21 February 2016.
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