This is my single most-requested recipe. I wasn't sure where to put it, but since it is an organic remedy, thought this might do it.
Squeeze the juice from a couple cloves of garlic into water, and let it steep for a day or two. Strain.
Add equal amounts of rubbing alcohol to the garlic-water solution and mix well.
Use 5 parts water to 1 part of the above mix, put in a sprayer, and use it to kill every hard-body and soft-body insect: beetles, grasshoppers, you name it. They die within an hour.
You might want to avoid using it in direct midday sun during the summer; the alcohol can magnify the sun's rays and burn the foliage. Better to use it in the morning or later in the afternoon on plants that are in full sun. I have used the above recipe with no ill-effects on any plant, except as noted.
As with any insecticide, use caution when handling it. Store unused portions in a cool, dark place away from the reach of children. Do not take internally.