A mixture of ½ cup rubbing alcohol and 1 quart of liquid soap can make an effective pest control spray to get rid of whiteflies, aphids, mealy bugs, scale insects, and thrips. Fill a spray bottle, shake, and spritz directly on your plants. Let sit for 20 minutes, and then rinse the plant thoroughly to avoid damaging the leaves. But save this garden maintenance 'til dusk; in direct sunlight, this can burn the leaves. Spray every three days for two weeks, until the bugs are gone.