**Jacaranda Aphids** (*Aphis jacarandae*) are small, specialized sap-feeding insects that infest trees in the genus *Jacaranda*, particularly the common **Blue Jacaranda** (*J. mimosifolia*). Like most aphids, they colonize tender new growth, stems, and leaf buds in dense clusters. Their feeding causes aesthetic damage, including leaf curl and yellowing. The most significant nuisance comes from their excretion of large quantities of sticky **honeydew**, which attracts ants and promotes the growth of black **sooty mold** on the distinctive purple flowers and foliage.
Taxonomy and Classification
Jacaranda Aphids belong to the order Hemiptera (true bugs), family Aphididae. They undergo incomplete metamorphosis. They are highly adapted to feeding on Jacaranda trees and share the same biological characteristics as other common aphids: high reproductive rates via asexual reproduction (parthenogenesis), short generation times, and an attraction to tender, fast-growing plant tissue.
Physical Description
Jacaranda Aphids are minute, pear-shaped insects, about 1 to 2 mm long.
- **Appearance:** Typically dark-colored (greenish-brown or black) with a shiny, soft body. They have the characteristic twin tubes (**cornicles**) projecting from the rear of the abdomen.
- **Location:** Found in dense, visible clusters on the undersides of new leaves and, critically, on the **tender flower stems** during the spring blooming period.
- **Damage Sign:** **Sticky residue (honeydew)** covering leaves, flowers, sidewalks, and cars beneath the tree. **Black sooty mold** often covers the honeydew. Infested leaves may be curled, deformed, or yellowing due to the continuous sap drainage.
Distribution and Habitat
Jacaranda Aphids are found worldwide wherever Jacaranda trees are cultivated as ornamental or street trees, particularly in subtropical and mild temperate zones (e.g., Southern California, Florida, South Africa, Australia). Their habitat is restricted to the new, soft growth of the host tree, where sap pressure is high.
Behavior and Conflict
The conflict is primarily aesthetic and a nuisance due to honeydew.
- **Honeydew Nuisance:** The sheer volume of sugary honeydew excreted by large colonies drips onto anything below the tree, becoming a mess that is difficult to clean and promotes mold growth.
- **Ant Association:** Ants often aggressively protect aphid colonies from natural predators (like lady beetles) because they “milk” the aphids for their honeydew. This complicates natural control.
- **Plant Health:** While large trees usually tolerate aphid feeding, heavy, untreated infestations can stunt new growth and stress young trees.
Management and Prevention
Control is integrated pest management (IPM), with a focus on non-chemical methods and protecting natural enemies.
- **Physical Removal:** For small or young trees, use a strong jet of water to forcefully dislodge the aphid colonies from the new growth. Repeat this every few days.
- **Horticultural Soap/Oil:** Apply insecticidal soap or neem oil to the infested areas, ensuring complete coverage, as these are contact controls. Timing this just before or during the first bloom is crucial.
- **Ant Control:** Control the ants first using a granular or liquid ant bait around the base of the tree. If ants are removed, natural predators (lady beetles, lacewings) can quickly suppress the aphid population.
- **Systemic Treatment:** For severe infestations on high-value trees, a systemic insecticide applied to the soil (via a drench or injection) can be used, but this should be timed carefully to minimize impact on pollinators.
Conservation and Research
Jacaranda Aphids are managed as high-impact ornamental pests. Research focuses on understanding the specific life cycle of the Jacaranda Aphid to improve the timing of treatment applications and conserving natural predator populations in urban environments.