The wavelength of subwoofers is way too long (meters) for something the size of a mosquito. Mosquitoes are ultrasound-sized. A mosquito destroying phased array of ultrasound transducers may be physically possible but probably even less practical than lasers.
If you actually want to create a shock wave, you need something that goes faster than the speed of sound, like high explosives... A lovely idea, but a bit overkill.
A small stoichiometric mixture of oxygen and hydrogen (created from electrolysis) might be able to create a shockwave or vortex with supersonic components for a range of 1-3m.
If you actually want to create a shock wave, you need something that goes faster than the speed of sound, like high explosives... A lovely idea, but a bit overkill.