Leafhoppers are small, widespread insects in the family Cicadellidae, a diverse group within the order Hemiptera. They inhabit environments globally where vascular plants grow. Primarily plant feeders, leafhoppers extract sap from a wide range of vegetation.
Identifying Leafhoppers
Leafhoppers typically measure between 1/8 to 1/4 inch (3-6 mm) in length, though some species can reach up to 1/2 inch (1 cm). Their bodies are slender and wedge-shaped, sometimes appearing triangular. They exhibit a wide array of colors, including green, brown, yellow, black, or gray, with some species displaying striking patterns like red and blue stripes.
They possess large eyes and short antennae. Their powerful hind legs are adapted for jumping, often featuring rows of small spines along their shins. When at rest, their wings are held in a roof-like position over their back and can be transparent or opaque depending on the species.
Life and Habits of Leafhoppers
Leafhoppers inhabit diverse environments, from gardens and agricultural fields to forests and grasslands. While some species are specific to certain host plants, many feed on a wide variety of vegetation, including grasses, shrubs, trees, and cultivated crops. Their diet consists exclusively of plant sap, which they access using specialized piercing-sucking mouthparts called rostrums.
When disturbed, leafhoppers rapidly hop away, an ability facilitated by their strong hind legs. They can also fly and move sideways. Their life cycle involves incomplete metamorphosis, progressing through three stages: egg, nymph, and adult. Females deposit eggs within host plant tissues, such as leaves, shoots, or stems. Nymphs hatch, resembling smaller, wingless adults, and undergo several molts before reaching maturity.
Leafhoppers and Their Impact
Leafhoppers damage plants primarily through feeding and by acting as disease vectors. Direct feeding results from their extraction of plant sap, leading to visible symptoms on foliage. Common signs include stippling, characterized by tiny white or yellow spots as chlorophyll is removed from leaves. Prolonged feeding can cause leaves to curl, distort, or deform.
Feeding can also lead to yellowing, browning, or scorching of leaf margins, often called “hopperburn.” Heavy infestations can stunt plant growth. Leafhoppers excrete a sticky substance called honeydew, which promotes the growth of black sooty mold on plant surfaces. The presence of small, whitish cast skins on the undersides of leaves indicates molting nymphs.
Beyond direct feeding, leafhoppers transmit various plant pathogens, including viruses, phytoplasmas, and bacteria. They acquire these pathogens by feeding on infected plants, where the pathogens multiply within the insect. When an infected leafhopper feeds on a healthy plant, it injects the pathogens through its salivary glands, infecting the new host.
Two notable diseases transmitted by leafhoppers are aster yellows and curly top virus.
Aster Yellows
Aster yellows, caused by a phytoplasma, is primarily spread by the aster leafhopper (Macrosteles quadrilineatus). It affects over 300 plant species, including vegetables like carrots, celery, and lettuce, and many ornamental flowers. Symptoms range from general yellowing and dwarfing to distorted foliage and abnormal flower development, such as green petals or bladder-like pods.
Curly Top Virus
Curly top virus, transmitted by the beet leafhopper (Circulifer tenellus), impacts over 300 species across 44 plant families, including important crops like beans, beets, tomatoes, and potatoes. Infected plants may exhibit crinkled, dwarfed, and upward-curled leaves, often with yellowing, purple veins, and stunted growth.