One method to keep bugs off tomato plants is to spray the plant with an insecticidal soap. This solution consists of 1 quart of water and 2 tablespoons of liquid dishwashing soap mixed into a spray bottle. The soap kills the bugs on the plants deters future invasions.
Tomato plants are especially afflicted with bugs when they plants are poorly maintained. Some pests that attack tomato plants include stink bugs, hornworms, aphids and fruit worms.
Commercial insecticides can also keep bugs off of tomato plants. Planting basil near a tomato plant may repel hornworms, and the presence of nearby thyme or lavender plants may deter slugs.
If bugs appear on tomato plants, they can be picked off of the plants and dropped into a bucket containing a solution of water and dish soap.