Leafhoppers damage carrots, lettuce, and potatoes.

Leafhoppers are small wedge-shaped insects with piercing-sucking mouthparts. Aster and potato leafhoppers can be problems in vegetable crops.

• Adult aster leafhoppers (Macrosteles fascifrons) are 1/10 inch long and dull light green with silvery-gray wings that fold back at rest. 
   
• Adult potato leafhoppers are green, 1/8-inch long, wedge-shaped, light yellow-green insects that jump and fly readily when disturbed. Nymphs are smaller and wingless. Nymphs are more likely to walk to the other side of the stem or leaf rather than jump. Both nymph and adult move in a characteristic "sidestep" pattern of walking, in which they move sideways rather than forward.

Damage Caused by Leafhoppers

Aster leafhoppers suck plant juices from plants, often giving leaves a whitened, mottled appearance.

• In addition to feeding, aster leafhoppers can transmit aster yellows disease to carrots and lettuce, and other plants in the aster family.
• Carrots infected with aster yellows tend to develop many hairy roots, become stunted, and turn pale.
• Lettuce infected with aster yellows will turn yellow, and leaves will become stunted and twisted.

Both potato leafhopper nymphs and adults suck sap out of leaves. When feeding, they inject a toxin into plants, causing them to curl, turn yellow, and then brown.

• Heavily damaged leaves drop from the plant. These symptoms are referred to as “Hopperburn.” 
• The insect attacks potato, eggplant, bean, and many other plants.
• Heavily injured beans are stunted with small root systems, resulting in reduced amount and quality of yield.
• They can also cause serious injury to bean seedlings through leaf feeding.  

Life Cycle of the Leafhopper

The aster leafhopper may overwinter in grasses and small grain crop fields in northern Illinois, but the majority of them migrate in late spring from the southern states. There are several generations per year.  

Management of Leafhoppers

Scout plants for adults using sweep nets and check underneath the leaf for nymphs.

Gardeners: Plants can be covered with row covers to prevent leafhoppers from attacking.

• Depending on the crop, they may need to be removed when plants begin flowering.
• Manage weeds around susceptible plants, as weeds can serve as alternative food sites.
• Pesticides can be applied to manage hoppers; read and follow all label directions.
• Remove and destroy plants that are infected with aster yellows to prevent spread.

Commercial: Monitor aster leafhoppers by using yellow sticky traps positioned above the crop canopy and spray insecticides recommended in your state when 5-10 leafhoppers per field are trapped on yellow sticky cards. Use row covers, reflective mulch, and elimination of weeds that are alternate hosts to aster leafhopper.

• Treat potatoes when there are two adult potato leafhoppers per sweep of a net or one adult per sweep plus fifteen nymphs per twenty-five leaves.
• Treat beans if populations exceed one adult per sweep or one nymph per ten leaves.
• For bean plants smaller than the two-true-leaf stage, treat if counts exceed one adult per two sweeps.
• Potato leafhoppers can be controlled by application of foliar and soil applied insecticides.

Contact your county Extension office for current pesticide controls.