Sunday, February 10, 2013

The ant-lion - a small delicate insect

The ant-lion is a small delicate insect that looks like a brown damselfly. The adult ant-lion has a weak flight and is most commonly found in vegetation in sandy areas especially along the west coast. Ant-lions have a worldwide distribution being particularly common in arid sandy habitats. There are about 2,000 species. About 12 species occur in the Maltese islands.

In most European and Mediterranean countries its name in some way or the other describes these insects as predators of ants. In Maltese they are known as qerd in-nemel. This is because the larvae feed mainly on small insects especially ants. The adults of some species feed on nectar and small pollen while others are predators of small arthropods.

The larva of the ant-lion digs a pit in the sand by crawling backward, using its abdomen as a plough to shovel up the soil. It uses one front leg to place heaps of particles on its head, which it then flicks away from the area in which it is digging. It continues working in this way as it moves sideways and inwards towards the centre creating a deep pit with steep sloping sides. When the pit is complete it settles down at the bottom buried in the sand with only its jaws protruding. 

Any insect venturing over the edge of the pit will find it difficult to maintain a hold on the loose sand and slips to the bottom where it will find the larva waiting with open jaws. If it tries to run up the steep sides the larva will shower it with loose sand to make it fall back to the bottom of the pit. There is no need for the larva to hit the escaping prey with sand. By removing sand from th ebottom of the pit, the larvae causes the sides to collapse bring the prey down with it.  

The ant-lion larva can capture and subdue a variety of insects and even small spiders. The projections in the jaws are hollow and it uses them to suck out the contents of its victims. It then flicks the dry carcass out of of the pit and arranges the pit by throwing out collapsed material from the centre to the sides making them as steep as possible in readiness for the next victim. 

This article was published in The Times on 1 July 2009

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