If you find a troublesome insect invading your garden, don’t make insecticides your first response. Pests can’t damage your plants if they can’t get to them. Block their access with simple, but effective barriers around your plants, such as the following:
Copper bands: Copper has the unique ability to repel slugs and snails. Their slimy coatings react chemically with copper, generating a toxic reaction — similar to an electric current — that sends them elsewhere. Use copper sheet metal to fashion permanent edging around your garden beds or staple copper-backed paper (available from garden centers) to the sides of wooden planter beds.
Dust barriers: You can repel some insects with a barrier of a sharp-particle dust, such as diatomaceous earth (DE), or wood ashes. Dusts work best when dry, and you have to reapply them after a rain.
Row covers: Developed to raise the temperature around plants and extend the growing season, these lightweight air- and water-permeable fabrics can also keep plants relatively safe from insect pests. Cover your plants early in the season, or the insects will have a chance to set up housekeeping in the garden and thrive under the protective covering. Remove the covers from plants, such as squash, that depend on insects for pollination when the plants bloom.
Cutworm collars: Make cutworm collars from empty toilet paper or paper towel rolls cut into 2-inch cylinders, or from strips of newspaper that encircle the stem completely, but not tightly, and extend 1 inch into the soil. Place the collars around transplants when you put them in the ground.
Sticky coatings: Halt insects in their tracks by applying a sticky coating to traps that attract specific insects. Make your own by mixing equal parts mineral oil or petroleum jelly and liquid dish soap, or purchase sticky substances at local hardware stores or garden centers. To make cleanup easier, cover the lure with plastic wrap before applying the sticky coating.