Christiaan Swanepoel on Instagram: "Have you heard them before? Giant burrowing crickets produce sound by stridulation—rubbing their front wings together. One wing has tiny ridges (a file) and the other acts as a scraper. The vibrations are amplified by thin wing membranes and their burrows, making the call loud and deep. #nature #wildlife #insect #naturephotography #southafrica"