Aphids are small, soft-bodied insects that frequently attack bougainvillea plants. They cluster on the undersides of leaves, stems, and flower bracts, sucking sap from the plant. This feeding weakens the bougainvillea, causing leaves to curl, yellow, or drop prematurely. Aphids also excrete honeydew, a sticky substance that attracts ants and promotes the growth of sooty mold, further harming the plant.
Spider mites are tiny arachnids that thrive in hot, dry conditions, making bougainvillea a common target. They pierce plant cells to feed, leading to stippling (tiny yellow or white spots) on leaves. Severe infestations cause leaves to turn bronze or brown and eventually fall off. Spider mites often produce fine webbing on the plant, which is a clear sign of their presence.
Whiteflies are small, winged insects that congregate on the undersides of bougainvillea leaves. Like aphids, they feed on plant sap, causing leaves to yellow, wilt, or drop. Whiteflies also excrete honeydew, leading to sooty mold. Their rapid reproduction makes them difficult to control, and they can transmit plant viruses, further compromising the bougainvillea's health.
Certain caterpillar species, such as the bougainvillea looper, specifically target bougainvillea. These larvae chew on leaves, creating irregular holes or skeletonizing them entirely. Heavy infestations can defoliate the plant, reducing its ability to photosynthesize and weakening its overall vigor. Caterpillars are often hidden under leaves or within rolled foliage.
Mealybugs are small, white, cottony pests that cluster on bougainvillea stems, leaf joints, and undersides of leaves. They suck sap, causing stunted growth, leaf yellowing, and premature leaf drop. Like aphids and whiteflies, mealybugs produce honeydew, attracting ants and fostering sooty mold. Their waxy coating makes them resistant to many pesticides.
Scale insects attach themselves to bougainvillea stems and leaves, forming hard or soft protective shells. They feed on plant sap, leading to yellowing leaves, stunted growth, and dieback. Heavy infestations can severely weaken the plant. Scales are often overlooked because their immobile adults resemble small bumps on the plant.
Thrips are slender, tiny insects that scrape bougainvillea leaves and flower bracts to feed on the sap. This causes silvery streaks, distorted growth, and premature flower drop. Thrips can also transmit viruses, compounding the damage. They are difficult to detect due to their small size and tendency to hide in buds or leaf crevices.
Snails and slugs are mollusks that chew irregular holes in bougainvillea leaves, especially in damp conditions. They are most active at night and during rainy weather. While they rarely kill the plant, their feeding can reduce its aesthetic appeal and weaken younger plants.
Leaf miners are the larvae of certain flies or moths that tunnel through bougainvillea leaves, creating winding, white trails. These trails disrupt photosynthesis and can cause leaves to curl or drop prematurely. While leaf miners rarely kill the plant, severe infestations can stress it and reduce flowering.
Root-knot nematodes are microscopic worms that attack bougainvillea roots, forming galls or knots. This disrupts water and nutrient uptake, leading to stunted growth, yellowing leaves, and overall decline. Infected plants may wilt easily, even with adequate watering. Nematodes are particularly problematic in sandy soils.
