Leafhoppers

About

Small, wedge-shaped insects, usually under 1/4 inch, that hop away or scuttle sideways when disturbed and suck sap from leaves. Most cause only cosmetic speckling, but a few spread plant diseases, such as aster yellows (aster leafhopper) and curly top (beet leafhopper) (UC IPM, UConn).

Spotting it

Damage

Feeding leaves pale stippling, like tiny bleached dots, that can spread until leaves yellow, brown or curl, and nymphs leave white cast skins under the leaves. Some species drip sticky honeydew that grows black sooty mold (UC IPM). Aster leafhoppers spread aster yellows, which leaves carrots stunted, pale and covered in hairy roots and turns lettuce yellow and twisted (Illinois).

How to find it early

Turn leaves over and look for quick, wedge-shaped insects running sideways, plus pale nymphs and white cast skins; yellow sticky cards also catch them. Stippling can look like spider mite, lace bug or thrips damage, so find the insect before you treat (UC IPM, UConn).

When

Late spring through fall; all stages can be found year-round in mild climates.

Life cycle

Females slip eggs into leaves and stems, and nymphs molt five times with no pupal stage; most species spend winter as eggs and have two or more generations a year (UC IPM). Many aster leafhoppers arrive each spring from southern states, and potato leafhoppers overwinter only in the warm Southeast (Illinois, UConn).

What to do, gentlest first

Start at the top. Sprays are a last step; always read and follow the product label.

1. Tolerate light speckling Prevent

   In most gardens leafhoppers are a nuisance, not a threat to the plant, and control usually isn't needed (UC IPM).

2. Pull weeds and diseased plants Prevent

   Remove nearby weeds that host leafhoppers, and pull and destroy plants infected with aster yellows (UC IPM, Illinois).

3. Row cover Barrier

   Cover carrots, lettuce and other crops with row cover to keep aster leafhoppers off (Illinois).

4. Natural enemies Natural enemies

   Assassin bugs, lacewings, damsel bugs, lady beetles, minute pirate bugs, spiders and tiny wasps that attack leafhopper eggs all help keep them in check (UC IPM).

5. Insecticidal soap, horticultural oil or neem oil Organic spray

   When nymphs are plentiful early in the season, spray leaf undersides and green shoots thoroughly with insecticidal soap, horticultural oil or neem oil (UC IPM).

   These work only on contact, and winged adults fly back in (UConn). Sprays don't prevent leafhopper-spread diseases, because the insects can pass on the disease before they die (UC IPM). Oil can harm bees for up to about 3 hours (PNW 591), so spray when bees aren't visiting, and follow the label.

Plants it goes after

Anise, Apple (backyard tree), Aster, Baby's breath, Carrot, Celeriac, Coreopsis (tickseed), Dry beans (pinto, black, kidney, navy), Eastern redbud, Eggplant, Endive and escarole, Flowering cherry, Flowering dogwood, Flowering tobacco (nicotiana), Grape, Green beans (snap beans), Hazelnut (filbert), Hops, Japanese maple, Kousa dogwood, Lettuce, Mamey sapote, Medlar, Mint, Potato, Purple coneflower (echinacea), Red maple, Rose (garden and landscape roses), Rosemary, Sage, Strawflower, Yacon

Pressure by region

Leafhoppers live in every region; California alone has more than 380 species (UC IPM). No source rated them by region, so ratings are estimates. See the potato leafhopper page for that eastern pest, which overwinters in the Gulf states.

Ratings come from extension sources where available; some are estimates, as noted above.