Garden insects often have a purpose that helps plants grow, and this is the case with ants and rhododendrons. The azalea and rhododendron are both from the same plant genus, rhododendron, but have distinct characteristics. Azaleas are deciduous, and rhododendrons are evergreen plants. Both attract pollinators and pests. One pest both attract is the aphid, which leaves a trail attractive to ants.
Aphids are a nuisance bug found on many garden plants and shrubs. They pierce leaves and suck out nutrients, which can transfer viruses to the plant. Aphids leave a trail called honeydew, a sweet and sticky residue. This residue may cause a sooty mold if it is left on leaves. Other pests such as mealy bugs also leave a honeydew trail.
Garden pests and insects find something in the garden attractive to feed on; for ants, this is honeydew, which also attracts ladybugs and lacewings. Plant pollen then sticks to the honeydew on the ants.
Ants need constant energy from a readily available food source, and they carry this food back to the colony. Ants can be predators of aphids and other garden pests. Ants may also increase the decay of other organic matter around the plant, which enriches the soil.
The rhododendron reproduces by pollinating the next plant and flower. This pollen is carried by insects and by wind or water. Along with butterflies and bees, ants carry pollen. This is a mutually beneficial relationship, a symbiosis; the ants eat the honeydew trails, helping both the rhododendron and the ant colony. This balance is a sign of a healthy ecosystem in the garden.
Rhododendrons are a hardy plant once established in a proper setting. They like a shaded area with acidic soil and are often found in forested areas with an organic layer on the soil. Rhododendrons need protection from winter winds and strong sun. The higher tree canopy in a wooded area provides this protection.