''Euroleon nostras'' is a
species
In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...
of
antlion
The antlions are a group of about 2,000 species of insect in the neuropteran family Myrmeleontidae. They are known for the predatory habits of their larvae, which mostly dig pits to trap passing ants or other prey. In North America, the larva ...
found over most of Europe. The scientific name can be translated as "our European
ntlion". Adults resemble dragonflies or damselflies and may reach up to long, with a wingspan of . The
larva
A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle.
Th ...
e prey on ants and other small creatures and require dry sandy soil in which to dig their pitfall traps.
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
A dragonfly is a flying insect belonging to the infraorder Anisoptera below the order Odonata. About 3,000 extant species of true dragonfly are known. Most are tropical, with fewer species in temperate regions. Loss of wetland habitat threate ...
or
damselfly
Damselflies are flying insects of the suborder Zygoptera in the order Odonata. They are similar to dragonflies, which constitute the other odonatan suborder, Anisoptera, but are smaller and have slimmer bodies. Most species fold the wings alo ...
in appearance. It is about long with a wingspan of about . The four large translucent wings are spotted with brown.
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. It is an extremely rare insect in Britain, known only from the
Minsmere
Minsmere is a place in the English county of Suffolk. It is located on the North Sea coast around north of Leiston and south-east of Westleton within the Suffolk Coast and Heaths AONB. It is the site of the Minsmere RSPB reserve and the origina ...
area of the
Suffolk
Suffolk () is a ceremonial county of England in East Anglia. It borders Norfolk to the north, Cambridgeshire to the west and Essex to the south; the North Sea lies to the east. The county town is Ipswich; other important towns include L ...
coast and
Holkham National Nature Reserve in
Norfolk
Norfolk () is a ceremonial and non-metropolitan county in East Anglia in England. It borders Lincolnshire to the north-west, Cambridgeshire to the west and south-west, and Suffolk to the south. Its northern and eastern boundaries are the Nort ...
.
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. 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
An instar (, from the Latin '' īnstar'', "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (''ecdysis''), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow o ...
larvae required more space for their larger pits. In conditions of overcrowding,
cannibalism
Cannibalism is the act of consuming another individual of the same species as food. Cannibalism is a common ecological interaction in the animal kingdom and has been recorded in more than 1,500 species. Human cannibalism is well documented, b ...
took place. In an experiment where the larvae were stocked at 1000 per square metre, about half were killed and eaten by other larvae.
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
The ovipositor is a tube-like organ used by some animals, especially insects, for the laying of eggs. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typica ...
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.
References
{{Taxonbar, from=Q1317005
Myrmeleontinae
Insects described in 1785
Neuroptera of Europe