Loudest
The African cicada wins the the William Hung Prize for loudest, and consequently most annoying bugger. Entomologist John Petti, who selected the champion, limited the contenders to insects humans could hear.
Male African cicadas produce alarm calls and calling songs with an intensity of about 110 decibels from 20 inches away. By comparison, a jet flying at about 1,000 feet buzzes at just over 100 decibels and live rock music at about 110 decibels.
Males use their tymbal muscles to sing. When they contract and expand these chitinous structures, the muscles click, and the sound amplifies as it travels through the body. Males usually sing together, producing a very loud, often deafening, chorus. Bigger males tend to have louder calls, giving them a competitive advantage with the ladies and in fending off predators (by annoying them).
Challengers included the bladder grasshopper and the European mole cricket, which make sounds of nearly 100 decibels at a distance of 20 inches.
Image: Annual cicada, Bruce Marlin / Wikimedia Commons.