Pyrethrin is an insecticidal compound derived from the chrysanthemum. It effectively controls a wide variety of garden pests including moths, beetles and slugs. For smaller, soft-bodied insects, an effective insecticidal spray can be made by combining a few drops of thyme essential oil and orange essential oil with a squirt of liquid soap in a spray bottle of water and applying liberally to the affected plants and the soil beneath them. This kills many bugs on contact and is quite safe for humans. With both the homemade spray and the pyrethrin extract, you will need to re-apply after a rainfall as the insecticide is water soluble.