Q: I have heard that eating garlic or spraying it around the yard will repel mosquitoes. Is this true?
A: The very first fact to chew on is that mosquitoes have almost no olfactory powers. They do sense odors in a very narrow spectrum related only to their pheromones. So if they can’t smell garlic, they can’t be repelled by it.
Mosquito repellents work not by repelling the insect by smell but by blocking their ability to smell things that otherwise would attract them. If they can’t sense you, they ignore you.
Mosquitoes are attracted to gaseous carbon dioxide, lactic acid and octenol. The best substance to block a mosquito’s power of detection is N,N-diethyl-meta-toluamide, commonly called DEET.
Truthfully, other chemicals such as those in citronella, cedar, verbena, geranium, lavender, pine, cinnamon, rosemary, basil, thyme and peppermint also block mosquitoes’ senses – but they only last a couple of hours.
If you are going to be exposed to mosquitoes for more than an hour or two, you should get a good DEET-based spray or lotion and stick with it.