Common cockroaches, such as the American and German species, are not known for making noise. While these pests are sometimes reported to make a clicking sound, this is likely a case of the observer misidentifying click beetles as cockroaches. However, if populations of cockroaches are large enough, the noise of their fluttering wings is audible. The noise typically associated with cockroaches is the crunch sound they make when smashed. The Madagascar hissing cockroach, one of the largest species of the pest, is an exception to the rule. They get their name from the hissing noise made through small openings in their sides, called spiracles. Hissing cockroaches make these sounds when threatened, fighting, or attracting mates. Some Australian cockroaches also produce sounds, creating acoustic vibrations to attract mates by rubbing their legs or wings together. Otherwise, there is no evidence of vocalization between cockroaches. Instead, much like other insects, they communicate with each other by means of pheromones.