Before mating, males and females may stridulate, or vibrate the objects they are on. Stephen Butler notes that the larvae stridulate when disturbed. Many Solifugae stridulate with their chelicerae, producing a rattling noise. Males also stridulate for courtship, though usually only when all other tactics have failed. In response to threats, Goliath birdeaters stridulate by rubbing setae on their pedipalps and legs. "S. cristantum" males will stridulate more often than "S. collare" males. Some species of venomous snakes stridulate as part of a threat display. Individuals stridulate to dissuade other hydropsychids from attempts to steal their retreats. The three species of the genus stridulate by rubbing setae on their pedipalps and legs. Male panorpids vibrate their wings or even stridulate while approaching a female. Most spiders are silent, but some tarantula species are known to stridulate. Insects and other arthropods stridulate by rubbing together two parts of the body. Most female crickets lack the necessary adaptations to stridulate, so make no sound. Some setae are used to stridulate, which makes a hissing sound. Marine catfishes, sea horses and grunts stridulate by rubbing together skeletal parts, teeth or spines.