Aphids, or simply plant lice, are tiny little insects that feed off your plants. They are 1-10mm long and once you spot them they are probably with many.

Aphids cause malformed flowers, leaves, and fruits on your lawn plants. If your lawn has an infestation of aphids, you can spray infected plants with diluted soap water, then with clear water. Concentrate on the infected areas of your plants’ stems, buds, and leaves. This technique works with even the strongest aphid infestations. 

Alternatively, you can set out ladybugs to get rid of them, ladybugs are a natural enemy of the Aphid.