Leafhoppers are small, sap-sucking insects found globally, belonging to the family Cicadellidae. They are common agricultural and garden pests because of their direct feeding damage and their role in spreading plant diseases. With over 20,000 described species, these insects feed on many plants, including grasses, trees, vegetables, and ornamentals. Their impact ranges from minor cosmetic damage to the total loss of a crop or landscape plant.
Identifying Characteristics
Adult leafhoppers are slender and wedge-shaped, typically measuring between 1/8 and 1/4 inch (3 to 6 mm) long. Coloration varies, including shades of green, yellow, brown, and gray, often with distinctive patterns. When at rest, their wings are held in a roof-like position over their bodies.
A defining feature is the presence of rows of small, rigid spines running the length of their hind legs. When disturbed, they are active, walking rapidly or using their powerful hind legs to jump or fly away quickly. Nymphs, the immature stages, resemble smaller, wingless adults and are often found on the undersides of leaves, leaving behind pale, shed skins.
Feeding Habits and Plant Injury
Leafhoppers possess piercing-sucking mouthparts, known as stylets, which they insert into plant tissue to feed on internal fluids. Different species target specific parts of the plant’s vascular system, feeding on either the xylem (which transports water) or the phloem (which transports sugars and nutrients). This removal of plant sap depletes the plant’s resources and reduces its vigor, especially in young or heavily infested plants.
Direct damage appears as fine white or yellow specks, called stippling or flecking, concentrated on the upper surface of the leaves where cell contents have been emptied. A more severe symptom is “hopperburn,” a distinctive browning, curling, and eventual death of the leaf tips and margins. Hopperburn is often associated with species like the potato leafhopper, which injects a toxic substance while feeding, disrupting nutrient movement.
Transmitting Plant Diseases
The most significant threat leafhoppers pose is their ability to act as vectors for various plant pathogens. They can transmit over 80 types of plant diseases, including those caused by viruses and bacteria, such as phytoplasmas. The insects acquire the pathogen by feeding on an infected plant and then introduce it into a healthy plant when they feed again.
Specific examples include Aster Yellows, spread by the aster leafhopper, which causes yellowing and stunted growth in crops like carrots and lettuce. Another destructive disease is the curly top virus, vectored by the beet leafhopper, which causes leaves to become crinkled and curled in numerous vegetables. Once infected, there is typically no chemical cure, and the disease often leads to stunted growth, distorted foliage, or plant death.
Managing Leafhopper Populations
Effective management often begins with cultural controls focused on the plant’s environment. Removing weeds and alternate host plants eliminates breeding and feeding sites. Using reflective mulches around plants is an effective physical control, as the bright light reflected upward deters leafhoppers from landing and laying eggs.
Biological controls involve encouraging natural enemies, such as lady beetles, lacewings, and parasitic wasps, which prey on leafhopper eggs and nymphs. Chemical control, such as insecticidal soaps or targeted insecticides, is typically reserved as a last resort for severe infestations. If chemical treatments are necessary, applying them only when populations reach a damaging level helps protect beneficial insect species.