**Ivy Leaf Bugs** (*Metcalfa pruinosa*) are small, waxy, sap-feeding insects in the plant hopper family, which includes the more common Froghoppers and Spittlebugs. They are generalist feeders that occasionally infest **ivy** (*Hedera* spp.) but can also be found on numerous fruit trees, ornamentals, and vegetables. They cause damage by piercing the plant tissue to suck sap, leading to wilting, reduced vigor, and the production of large quantities of sticky honeydew and black sooty mold.
Taxonomy and Classification
Ivy Leaf Bugs belong to the order Hemiptera (true bugs), family Flatidae (flatid planthoppers). They undergo incomplete metamorphosis. They are closely related to cicadas and leafhoppers. They are easily recognizable by the dense, white, mealy wax coating that covers their entire body, giving them a distinct, ghost-like appearance as they hop on leaves.
Physical Description
Adult Ivy Leaf Bugs are wedge-shaped and 1/4 to 3/8 inch long.
- **Appearance:** Covered entirely by a thick, powdery, white or grayish-blue wax, making them look fuzzy or mealy. The body underneath the wax is dark brown or black.
- **Nymphs:** Small, slow-moving, and covered in white, filamentous wax, often resembling tiny, fluffy cotton balls. They are usually found stationary on the undersides of leaves and stems.
- **Movement:** They are active jumpers. When disturbed, the adults rapidly leap away, often accompanied by a cloud of their dusty wax.
- **Damage Sign:** Leaves become sticky due to sweet **honeydew** excretion. A subsequent coating of black **sooty mold** grows on the honeydew, blocking sunlight and reducing plant health and aesthetic appeal.
Distribution and Habitat
Ivy Leaf Bugs are native to North America but have become an invasive agricultural and ornamental pest in Europe (e.g., Italy, France). Their habitat is the foliage and tender stems of a wide variety of plants. They are prevalent in areas with dense vegetation, hedges, and ivy growth, where they feed throughout the summer.
Behavior and Conflict
The bugs feed on the plant’s phloem by piercing the stems and leaves with their mouthparts.
- **Honeydew Production:** Like aphids, their copious excretion of sticky honeydew is the primary nuisance. It contaminates the host plant, furniture, and objects below the plant, leading to the growth of sooty mold.
- **Aesthetic Damage:** The black sooty mold coating the leaves severely impacts the appearance of ornamental plants.
- **Plant Stress:** Although typically not fatal, heavy, chronic feeding can stunt new growth, weaken young plants, and reduce the yield of fruit-bearing hosts.
Management and Prevention
Control is integrated pest management (IPM), targeting the sedentary nymph stage.
- **Monitoring:** Inspect plants for the white, fluffy nymphs and for sticky honeydew residue, especially on the undersides of leaves.
- **Pruning:** Remove and destroy heavily infested plant parts and dense, overgrown sections of ivy to improve light and air circulation.
- **Physical Removal:** On small plants, a strong jet of water can wash off many nymphs and adults, temporarily reducing the population.
- **Horticultural Oil/Soap:** Apply insecticidal soap or narrow-range horticultural oil. These materials work by smothering the insect, requiring excellent coverage, especially since the nymphs are covered in wax.
- **Biological Control:** Natural predators, such as spiders, birds, and generalist lacewings, often keep populations suppressed in balanced ecosystems.
Conservation and Research
Ivy Leaf Bugs are managed as ornamental and invasive agricultural pests in regions where they have been introduced. Research focuses on effective biological controls (e.g., parasitic wasps) to suppress populations in newly invaded areas and to reduce the reliance on chemical controls in sensitive fruit crops.