There is an insect repellant you can make by whizzing one medium onion, 1 garlic bulb, and a tablespoon of hot pepper flakes with enough water to cover in your blender letting that steep for at least 24 hours and then straining that mixture and adding 1 cup of that to 1 gallon of water and spraying that around. That is an insect repellant not a pesticide, it does not kill insects. Garlic powder does not seem to work in this mixture. Some chili powders may, depending on how hot they are.
Which pesticide you might think about using depends on which insect you need to control and at which stage of life they are. Some are effective in very early larval stages while others might be effective when used to control adults. However, any pesticide that will control adult insects are very broad spectrum poisons that will also kill beneficial insects.