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An acoustic weapon that blows apart the guts of mosquito larvae has been patented by Michael and Herbert Nyberg of Connecticut (WO 02/052933). In their chemical-free insecticidal scheme, a boat criss-crosses the water where the mosquitoes breed, trailing a waterproofed loudspeaker that reproduces a sweep of high-frequency sound in the 16 to 32 kilohertz range. This triggers resonance in the small air bladder in a larva’s thorax, making it behave like a miniature organ pipe. The vibrations destroy the surrounding tissue and eventually force the bladder into the larva’s abdomen, which kills it. The inventors say a 100-watt sound source can finish off larvae within a range of about 25 metres.