The first sign of aphids are curling leaves. Aphids attack the plant by sucking the plant’s sap. Apply soapy water to both sides of the leaves at the first sign of aphids. Natural predators include lady bugs (you can buy ladybugs and release them in your garden). Other beneficial insects include lacewings and hover flies which are attracted to parsley, dill, Queen Anne’s Lace and Nasturtiums.
Aphids are the major pests for peas; luckily, they are easily controlled by spraying the plants with cold water to knock the bugs to the ground. If a heavy infestation occurs, resort to an organic insecticidal soap spray or check the approved list in Gardening 101.
Note: aphids and ants have a symbiotic relationship, so if you have aphids you will probably have ants as well. To get rid of ants, use mint, camphor, cloves and hot peppers to keep them away.