Suffolk ant-lion (Euroleon nostras)
| Kingdom | Animalia |
|---|---|
| Phylum | Arthropoda |
| Class | Insecta |
| Order | Neuroptera |
| Family | Myrmeleontidae |
| Genus | Euroleon (1) |
| Size | Adult length: 30 mm (2) Adult wingspan: 70 mm (2) |
Not listed under any conservation designations or legislation (1).
Ant-lions are fascinating insects that belong to the same order as the more familiar lacewings. Free-flying Euroleon nostras adults are brown in colour and are generally similar in appearance to dragonflies and damselflies; however, the four large wings are decorated with dark spots, which allows the species to be easily identified (2). Larvae are very different in appearance to the adults; they are voracious predators with huge jaws, and the name ant-lion refers to this stage, not to the adults (2).
In Great Britain, this ant-lion is known only from a few sites in Suffolk (2). It was first confirmed as a resident breeding species in Britain as recently as 1996, having first been recorded (under the wrong name) in 1781 (2).
The larvae of this species require undisturbed sandy and dry soil, close to vertical sandy ledges that help adults to emerge successfully (2). The adults need tall, isolated Scots pine trees (Pinus sylvestris) nearby, in which mating takes place (2).
The larvae spend their life underground; they create 'ant-lion pits', by burrowing backwards into the sand. The larva buries into the bottom of the pit but leaves its jaws sticking out. When unsuspecting insects, woodlice, spiders and millipedes pass by the pit, the ant-lion larva starts to flick sand at them until they fall in, where they are grabbed by the huge jaws (2), sucked dry and then tossed out of the pit (3). Occasionally the larva may emerge in order to chase its prey, whilst showering it with sand (2). The body of the larva is covered with forward-facing bristles that prevent it from becoming dislodged from its pit. These hairs mean that larvae can only move backwards (2).
Larval ant-lions digest their food so well that they do not produce solid waste; they therefore do not need an anus. Larvae exude only liquid waste; the small amount of solid waste that may build up is excreted by newly emerged adults (2). Ant-lion larvae pass through three stages (called instars) and overwinter twice, before spinning a tough silk cocoon, and entering the pupal stage. Adults emerge from the pupa towards the end of July or in the first few days of August (2). After allowing their wings to harden (3) they gather in a tall pine tree, and a number of males attempt to attract a single female. Volatile compounds given off by males have been discovered; these compounds are thought to stimulate these aggregations (3). Mating involves the male hanging below the female, with his tail attached to that of the female (3). After mating, the female flies to the ground, where she lays her eggs in the sand. She has to be particularly wary of ant-lion larvae at this time, which are the main predators of female adults. Males live for up to 20 days, while females last a little longer, with an average life span of 24 days (2).
This species occurs in relatively low numbers in all known UK sites. It has a very limited range, and fairly precise habitat requirements. It is therefore very vulnerable, and is also susceptible to over-collecting and habitat change (2).
Most colonies of the Suffolk ant-lion occur in the RSPB Minsmere reserve, and more than 80% of the larvae occur in a restricted area not open to the public (2). It seems that it may be possible to create suitable habitat for this species, but further research into the ecology of this fascinating insect is needed if conservation action is to be effective (2).
For more on ant-lions see: The ant-lion pit.
http://www.antlionpit.com/
This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact: arkive@wildscreen.org.uk
- Larvae: stage in an animal's lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.
- Larval: of the stage in an animal's lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.
- Pupal stage: stage in an insect's development, when huge changes occur that reorganise the larval form into the adult form. In butterflies the pupa is also called a chrysalis.
- National Biodiversity Network Species Dictionary (August 2002): http://www.nhm.ac.uk/nbn/
- Plant, C. W (1999). The Suffolk ant-lion Euroleon nostras. British Wildlife, 10 (5): 303-309.
- The ant-lion pit. (August 2002): http://www.antlionpit.com/