The ants feed on the honeydew produced by the aphids and protect the aphids in return, often keeping their eggs through the winter in their nests. In the spring, the ants transport the aphids to host plants and then protect them from enemies. Aphid colony on rose The honeydew is a sticky, sweet substance that is produced by the aphids when they can't use all of the sugar taken from plants. It can drip from infested trees or shrubs onto cars, sidewalks, and porches creating quite a mess. You may see a black, sooty mold growing on it.
Natural enemies play an important part in controlling aphids.
Lady beetles, lacewings, damsel bugs, flower fly maggots, certain parasitic wasps, birds, and fungal diseases all attack aphids. Ladybugs prey on aphids, control small infestations and can be added to your garden. You can avoid the use of chemical sprays if predators are abundant. Control ant populations by setting traps or destroying colonies. Fungi that attack aphids are also becoming commercially available.