It is unhealthy to use chemical insecticides on many types of fruit. Fruit such as peaches, grapes, plums and strawberries have thin skins and are especially capable of absorbing chemicals. Many types of bugs, however, are attracted to the sweetness of thin-skinned fruits, making them susceptible to infestations. Ants are an example of an invasive insect that is attracted to thin-skinned fruits, like strawberries.
Sprinkle diatomaceous earth on the surface of the soil in the strawberry patch. Diatomaceous earth is made up of ground, fossilized algae. As the ants attempt to tread over the diatomaceous earth, the earth's razor-sharp particulates will puncture their outer coatings. The compromised exoskeletons will render the ants unable to retain moisture and eventually lead to their deaths due to dehydration. You can also sprinkle diatomaceous earth around any ant mounds found nearby.
Similar to diatomaceous earth, soap works by breaking up the waxy exoskeletons of ants. Once the protective coating is damaged, ants become unable to hold in water and eventually dry out and expire. Create a solution of dish or soy soap and water and regularly saturate the strawberry leaves with the mixture, using a spray bottle. Use 1 tbsp. of soap per cup of water to make a strong solution. The soap and water can also be used to douse ant colonies; pour sudsy, boiling hot water directly onto the anthill. Even more effective when poured on a colony than dish soap is lye boiled in water. Use 2 tbsp. of lye per gallon of water. Avoid skin contact when working with lye, as pure lye is caustic. Another option is to sprinkle borax on a platter containing jam or syrup. Place the platter in the strawberry patch, where the ants will inadvertently feed on the borax.
Next season, include plants throughout your garden that naturally repel ants. Plant ant-repellent plants throughout the garden, and around the perimeter of or in alternating rows with the strawberries. Plants that naturally repel ants typically do so through scent. Options include pennyroyal, spearmint, sage and catnip. Alternately or in addition to living ant repellants, the leaves of these plants can be dried and sprinkled on the strawberry patch.