Leafhoppers and planthoppers

Overview

Numerous species of leafhoppers and planthoppers are found in Missouri, and many of them have a broad host list (for example, the potato leafhopper, Empoasca fabae, has over 100 host plants). They feed on foliage and shoots of many different plant species by piercing the plant cells and sucking out the contents. The damage that results from feeding depends on the host plant and the specific hopper. Only a few species of hoppers transmit pathogens such as those that cause curly top virus and aster yellows. Adult hoppers are excellent short-distance jumpers when disturbed, and they can be pests when found in high numbers.

Symptoms and Diagnosis

Hoppers are agile insects that can move with equal ease either forwards, backward, or sideways like a crab. The crab-like motion distinguishes hoppers from most other insects. In addition, they can hop to escape danger or to move to another host plant.

Feeding damage from some species causes small white spots (stippling) to appear on the upper leaf surface, usually beginning near the leaf midrib.

Stippled areas can unite into larger whitish blotches on mature leaves. With some plants, feeding damage causes a drying and yellowing (or browning) of leaf margins, and possibly the whole leaf. Some leafhopper species cause curling or stunting of terminal leaves with their feeding. Another sign of feeding is the presence of tiny varnish-like spots of excrement on the underside of leaves. Also, check under leaves for white, papery cast skins that remain from the molting process. Check also for honeydew excreted in large amounts, which may encourage the growth of sooty black mold.

One variety of hopper, known as the beet leafhopper, is 1/8 of an inch long, pale green or yellow, and resembles a tiny white fly when flying. It carries a tomato virus for which there are no controls once plants become infected. Symptoms of this virus include a pronounced upward rolling of fully developed leaves, leaves turning yellowish with purple veins, foliage becoming stiff and brittle, and eventual mortality. Another variety of hoppers, the potato leafhopper, can reduce potato yields significantly by secreting substances which decrease plants' photosynthesis.

The lace bug is another insect that causes stippling from feeding and leaves dark droplets of varnish-like excrement on the underside of leaves. Distinguishing lace bugs from leafhoppers is easy:

Lacebugs have a lacy pattern on their upper side, they don't jump or run sideways, and they are about half as broad as they are long. Yet another pest that can cause stippling is the spider mite. Check under leaves for the webbing left by spider mites (leafhoppers don't leave webbing).

Life Cycle

Adults of most species of leafhopper range between 1/8 to 1/4 inch long. They are slender and frequently have an angular, pointed head. Coloration depends on species, but generally leafhoppers are shades of green, brown, or yellow and are often mottled. Nymphs (immatures) look similar to the adults except that the nymphs are smaller and don't have wings. Nymphs typically feed on the underside of leaves, where the humidity is higher and they are more protected from predators.

Leafhoppers have several generations each year. Some species migrate south in winter and return north with late spring weather.

Integrated Pest Management Strategies

1. Live with the pests. Because of their mobility and abundance, leafhoppers are not easy to control. However, leafhoppers are seldom present in large enough numbers to seriously injure plants. In addition, leafhoppers have many natural enemies, including lady beetles, lacewings, damsel bugs, spiders, and birds. They are also subject to diseases and parasites that help keep their numbers down under most conditions. Attracting chickadees, purple finches, sparrows, swallows, titmice, and wrens to your yard may help as all eat hoppers.

2. Use row covers. Floating row covers or netting can be placed over plants early in summer to exclude leafhoppers. Remove row covers when the plants begin to flower.

3. Monitor with sticky traps. Many leafhoppers are attracted to yellow sticky traps which should be placed close to the foliage of the crop. Populations can be monitored with sticky traps and low populations can be managed using these traps.

4. Apply insecticidal soap. Insecticidal soap can control leafhoppers if applied when the insects are small. The immature leafhoppers are usually found on the underside of leaves so be sure to spray there also.

5. Apply insecticides. Other insecticides available for leafhopper control include pyrethrins, malathion, bifenthrin, cyfluthrin, disulfoton, and acephate. In general, these are most effective on immature leafhoppers because they can't escape as well as adults and are typically more susceptible to chemicals.

Organic Strategies

Strategies 1, 2, and 3 are strictly organic approaches. For an organic approach to Strategies 4 and 5, consult the Organic Materials Review Institute (OMRI™) for appropriate insecticidal soap and pyrethrin products.

Pesticide Disclaimer: 

Always follow the product's label and ensure the product is effective against leaf and plant hoppers. Not following the pesticide label before usage is a violation of federal law.