Crickets are the most visible animals in many caves, apart from bats. They are troglophiles in that they only use the cave for shelter and laying eggs. They leave the cave at night during the summer to forage for food up to about 300 feet from the entrance.
The most common cricket that lives in caves in the United States is Hadenoecus subterraneus. It is common to see up to thousands of them near cave entrances at nightfall. They leave the cave when it is dark and conditions outside such as humidity and temperature are similar to inside the cave.
Once outside, they will eat almost anything, including mushrooms, berries, flowers, animal droppings and dead insects. Inside the cave, their droppings are a food source for other cave animals.
Cave crickets can be found in many other parts of the world also. Here is one found in Chiang Dao Cave, Thailand…
Outside the cave, crickets have many enemies, including birds and small rodents. Even around cave entrances, they are a favorite meal of the white-footed mouse. They are relatively safe inside the cave except for their eggs.
Several species of North American beetles use cricket eggs as their main food source. In some areas these beetles will eat over 90% of the eggs that are laid. Fortunately for the crickets (and the beetles), they lay up to 200 eggs per year and the cricket population is often over 5,000.
Although they are not true troglobites, these crickets don’t leave the cave during the day in the summer and not at all during the winter. They also have some adaptations to cave life such as longer antennae, resistance to starvation and lower metabolic rates.