An African cicada, Brevisana brevis, is the Worlds loudest insect. Its loudest song is almost 107 decibels when measured at a distance of 20 inches (50 cm) away. Thats almost as loud as a chainsaw (110 decibels).
Two North American cicada species are in close second with songs at 106 decibels.
Cicada songs are used to help them communicate with each other, find mates, and possibly drive away potential predators.
Dog Day Cicada