Cave Crickets, the 2023 Cave Animal of the Year: Commuters That Feed a Whole Ecosystem

Each year the National Speleological Society (NSS) names a Cave Animal of the Year to draw attention to life underground. For 2023 it chose cave crickets — which live in several caves in Great Basin National Park.

If you've caught a hop in the dark not far inside a cave entrance and looked closer, you may have met one.

A cave cricket and its long antennae. NPS/Gretchen Baker

What they are

North America has many kinds of cave crickets, including at least 33 species in the genus Ceuthophilus. Their family, Rhaphidiphoridae, is found worldwide; Ceuthophilus ranges from Canada to Mexico.

Life cycle

• Young crickets hatch from eggs looking like miniature adults, and grow slowly, molting each time they outgrow their exoskeleton.
• Adults don't live long — just long enough to mate and lay the next generation.
• Females may lay 2–6 eggs at a time in loose soil, and perhaps 30–60 in a lifetime, though little is known about this.
• Some live about one year, others closer to two.

People have noticed them for a very long time: a carving of a cave cricket in France is at least 12,000–17,000 years old, and a pictograph in one of Great Basin's caves may show one too.

Cave crickets often match the color of the rock. NPS/Gretchen Baker

Where they live

Ceuthophilus crickets usually live in caves — on the walls and ceilings, sometimes under rocks — but not always. Some visit caves only now and then and otherwise stay out of the sun under rotting logs and rocks or in boulder fields. Most spend most of their time in caves and go out to forage every few days; a few are so adapted to caves that they never leave. Which it is depends on the species and on what the surrounding habitat offers. Most need a fairly steady temperature and humidity, which is why caves suit them.

What they eat

Almost anything: they are omnivores, recorded eating fruit and grasses, meat (tuna), mushrooms and people's leftover food. Like many invertebrates, they switch foods several times a night to meet their needs.

• In New Mexico, studies of what was in their crops found that crickets living near cave entrances ate mostly green plants.
• In Texas, crickets painted at cave entrances were found to travel more than 100 m on their nightly rounds — and often to walk overland from one cave to another.

Why they matter

Cave crickets are trogloxenes: animals that use caves heavily but don't live only in them. They feed outside, then come back underground, leaving behind droppings (guano), shed exoskeletons, eggs and eventually their own bodies. Most caves have no primary production — nothing that makes food from sunlight — so the nutrients carried in by trogloxenes such as crickets and bats, along with floods, are vital to cave life. Crickets matter in particular because they wander all over a cave, spreading food in ways bats and floods don't.

Some cave animals depend on them directly. At least one genus of endangered ground beetle, Rhadine, specializes in cave cricket eggs: the crickets use their ovipositors to lay eggs in small holes in clay or silt walls, and the cave-adapted beetles follow the crickets' tracks by scent until they sometimes find a hole with an egg inside.

More from the NSS: Meet the 2023 USA Cave Animal of the Year.

Sources

Based on "Meet the 2023 USA Cave Animal of the Year: Cave Crickets!," by Jean Krejca and Shiloh McCollum of the Great Basin Institute, first published in The Midden (Great Basin National Park), Summer 2023, and posted by the National Park Service; rewritten in hubnx's own words.