Sonic and electronic devices do not work.
Sonic, electronic and ultrasonic devices have all been advertised as repelling mosquitoes. Some devices are available in a bracelet, watch or necklace form for personal protection while others plug into room outlets and claim to eliminate mosquitoes from a larger area. Manufacturers claim the devices imitate the flight sound of a male mosquito and work because a mated female mosquito would avoid further contact with males. Other devices were supposed to imitate the flight sounds of dragonflies.
A simple test is to find an area of mosquito activity, activate the device for a couple of minutes and then begin to count the mosquitoes that land on an exposed surface (like a leg or arm). Turn off the device and measure the number of landings on the same surface for the same amount of time. Repeat this three to five times and you should have a good range of landing catches to compare. Of course, you can always leave it up to scientists who have consistently found that these devices do not work.
References
Barrido R., Brown J., Novak R. and Berenbaum B. 1993. A test of the efficacy of ultrasonic mosquito repellers. The Vector Control Bulletin of the North Central States. 2:65-69.
Foster, W. A. and K. I. Lutes. 1985. Tests of ultrasonic emissions on mosquito attraction to hosts in a flight chamber. Journal of the American Mosquito Control Association. 1(2): 199 – 202.
Lewis, D. J., W. L. Fairchild and D. J. Leprince. 1982. Evaluation of an electronic mosquito repeller. Canadian Entomologist. 114(8): 699 – 702.
Schreiber E.T., Floore T.G., and Ruff J.P. 1991. Evaluation of an electronic mosquito repelling device with notes on the statistical test. Journal of the Florida Mosquito Control Association. 62:37-40.