There are tiny death traps in my front yard–ant lion pits.
One of the components of an integrated pest management plan is understanding the natural predators of a "pest" species. Ants are a common pest in suburban Los Angeles. Ants are attracted to the sweet and fat food stuffs abundant in our modern human diet. Invasive exotic species like the Argentine ant are also attracted to the water that people make available beyond natural amounts.
One ant predator is the descriptively named ant lion. This member of the ancient order of nerve-winged insects, Neuroptera, voraciously eats ants that tumble into its funnel-shaped pit made in loose sandy dirt. The hungry ant lion larva sits at the bottom of its excavated cone of loose soil. When an ant or other small insect troubles into the pit, grains of tumbling sand alert the ant lion that prey has entered its trap. The steep sides make escape difficult. Without warning the ant lion's fierce jaws snatch the frantic ant and consume it.
In several areas of the yard, small patches of sandy soil provide the perfect spot for these hidden ant traps. Throughout the summer little ant lion pits appear and disappear as the ant lions hunt, mature and eventually become delicate flying adults with elegant wings.
One of the rewards of not using pesticides, is the variety of insect predators that live in and visit our yard. Praying mantises, green lacewings, trapdoor spiders and ant lions are part of that biodiversity that maintains the natural balance in our yard and keeps the "pests" under control.
The next time you see an unusually perfect little pit in an out of the way place, take a second look. It could be an ant lion lair and an important insect predator.