Dr. Robert Norman, Clinical Professor, Dermatology, Nova Southeastern University
Who makes these circular depressions?
1. Antlion
2. The Concave Sandborer
3. Ground Wasp
4. Palmetto Beetle
5. Feral Sand Nymphs
The antlions (Distoleon tetragrammicus) are a group of about 2,000 species of insect in the family Myrmeleontidae that are known for the fiercely predatory habits of their larvae. Many species dig pits to trap passing ants or other prey. The adult insects are less well known and mostly fly at dusk or after dark. They may be mistakenly identified as dragonflies or damselflies and are sometimes known as antlion lacewings. In North America, the larvae are sometimes referred to as doodlebugs because of the strange marks they leave in the sand.
Antlions have a worldwide distribution with the greatest diversity occurring in the tropics. They most commonly occur in dry and sandy habitats where the larvae can easily excavate their pits, although some larvae hide under debris or ambush their prey among leaf litter.
In trap-building species, an average-sized larva digs a pit about 2 inches deep and 3 inches wide at the edge by starting with a circular groove and crawling backwards, using its abdomen as a plough to shovel up the soil. The steep-sloped trap, based on a critical angle of repose, guides prey into the larva’s mouth while avoiding crater avalanches. It is one of the simplest and most efficient traps in the animal kingdom.
Antlions are poorly represented in the fossil record. The antlions’ closest living relatives are thought to be the owlflies (Ascalaphidae). The predatory actions of the larvae have attracted attention throughout history, and antlions have been mentioned in literature since classical times. The term appears to go back to classical antiquity as the scientific name of the type genus Myrmeleo is derived from Ancient Greek léon (λέων) “lion” + mýrmex (μύρμηξ) “ant.”
In the 2nd century AD Physiologus, the Myrmecoleon was a mythical ant-lion hybrid used when animal descriptions were paired with Christian morals. Although the exact meaning of the name “antlion” is uncertain, it probably indicates that ants form a large percentage of the prey of the insect. Popular folklore in the southern United States include a poem or chant to make the antlion come out of its hole and similar cultural practices have been recorded other places throughout the world.
Where can you find these antlions?
Get out and look for them in the Great Florida Outdoors!
Dr. Norman is an advanced master naturalist graduate of the FMNP program from UF and a board-certified dermatologist based in Tampa and Riverview. He can be reached at 813-880-7546.