Feeding is not the only damage that leafhoppers can cause. Some leafhoppers also transmit plant diseases. Knowing how leafhoppers look during the different stages of their life cycle and identifying leafhopper damage is crucial to catching leafhoppers early when their numbers are low. This way, you can effectively control this pest before it becomes a heavy infestation.
What Do Leafhoppers Look Like?
The many different species of leafhoppers have some common characteristics. Adult leafhoppers are slender, wedge-shaped insects, and 1/8 to 1/2 inches long. Their colors range from green and yellow to brown, and they can be mottled or streaked. Some leafhoppers stand out with their bright color while others blend in with the host plant. Besides these physical characteristics that are visible to the naked eye, you can identify a leafhopper by the agile way it moves: rapidly, crawling sideways like a crab, jumping both forwards and backwards when disturbed, or hopping to another plant when they feel in danger. The ability to move sideways like crabs and jump sets leafhoppers apart from other similar insects. They are sometimes confused with aphids or lacebugs. Most leafhoppers go through two to three generations each year. Typically the populations peak between mid-summer and early fall. The earlier you spot leafhoppers, the better you’ll be able to control their numbers. Therefore, it is important to know how leafhoppers look—not only as adults but also during the other stages of their life cycle. Leafhoppers lay their eggs in plants, sometimes on the underside of leaves. In mild climates, leafhopper eggs can also overwinter and hatch when the weather warms up. Newly laid eggs hatch after a couple of weeks. The emerging nymphs, unlike the adults, initially don’t have wings. The nymphs go through five molting cycles, and they shed their skins called exoskeleton after each cycle. If you inspect the undersides of leaves, you might find both the nymphs feeding as well as the pale-colored, papery skins that they cast. In the later cycles, the nymphs develop small wing pads. Common leafhopper species in home gardens and landscapes include: Turfgrass leafhopper: The adults are 1/8 to 3/8 inches long and green to brown. Leafhopper feeding manifests itself as gray or silver spots in the turf. Later, the grass dries out and turns yellow and brown. Beet leafhopper: The adults are 1/8 inches long, pale green to tan, sometimes with brown markings. What makes the beet leafhopper a serious pest is that is transmits plant diseases. First and foremost, beet curly top virus which makes crops turn yellow or purple and inhibits plant growth; leaves and stems to turn stiff. Spring plantings are especially vulnerable. Potato leafhopper: The adults are 1/8 to ¼ inches long and limey green. Despite its name, the potato leafhopper also feeds on numerous crops such as beans, soybeans, legumes like eggplants, and other fruits like raspberries, apples and other fruit trees. It also feeds on common weeds such as smartweed, pigweed, and carpetweed. Two-spotted leafhopper: This leafhopper is native to Asia but is now also found in the United States. It is ¼ inches long, pale yellow with a brown stripe running down its back, and two prominent spots at the end of the wings. It feeds on various ornamental plants and makes them look chlorotic. Blue-green sharpshooter: This leafhopper is native to California. The adults are up to ½ inches long with green to bright blue wings, head, and thorax. It feeds on ornamental plants and edibles. One of its favorite foods are grapes, and it is much feared in the wine-growing industry. The leafhopper transmits Pierce’s Disease, a bacterial disease that blocks the flow of water and nutrients in a plant. Glassy-winged sharpshooter: The adults are about ½ inches long and dark brown with translucent wings. This leafhopper was initially in the southeastern region of the United States but has moved to California where the insects overwinter as adults, which they start laying their eggs in early February. It feeds on a wide range of plant species and also transmits Pierce’s Disease, making it a much-feared pest in vineyards. Aster leafhopper: The adults are up to ½ inches long and olive green with three pairs of spots on their heads, which also gave them their name as six-spotted leafhoppers. They transmit the plant disease aster yellows, which they get by feeding on infected plants.
4 Ways to Get Rid of Leafhoppers
Before you take measures to get rid of leafhoppers, determine the level of infestation. Just a few leafhoppers won’t cause serious injury to your plants, and natural predators can usually take care of them. But at the same time, you want to make sure that you control their numbers before they become a major infestation. Adult leafhoppers move rapidly which makes them difficult to control. Any control measures should aim at getting rid of the eggs or larvae.
Biological Control
The first measure of biological control is to encourage beneficial insects such as ladybugs, lacewings, and minute pirate bugs because they are the natural enemies of leafhoppers and keep their population under control. They not only take care of leafhoppers but also feed on other pests, such as aphids, armyworms, and spider mites.
Chemical Control
Any chemical products should be used on the immature nymphs only. They cannot hop away like the adults, and they are more susceptible to chemicals. Thoroughly spray the leaves with insecticidal soap, especially the underside of leaves where the nymphs like to dwell and feed. To control a major infestation, you might need to notch it up and apply an insecticide such as a product containing pyrethrins or carbaryl. Keep in mind that any broad-spectrum insecticide will also kill beneficial insects, so apply it in a highly targeted manner only on infested plants. Do not irrigate the plants for 24 hours after application. If you live in a warm climate where leafhoppers overwinter, you can protect fruit trees, roses, and other ornamental plants from leafhoppers by applying dormant oil.
Removal of Infested Plants
When plants, especially annuals such as crops, are heavily infested, it is often better to completely remove them than treating it with chemicals. Safely dispose of infested plants in the garbage.
Mechanical Control
Floating row covers can keep leafhoppers away from garden crops. However, they must be removed when flowering begins, even for self-pollinating vegetables because the lack of air circulation and wind can lead to reduced pollination. Floating row covers have the added benefit that they keep other pests such as flea beetles out. Another way of keeping leafhopper populations at bay is to put up yellow sticky traps near plants that they like to feed on. But just like with insecticides, sticky traps can also harm beneficial insects.
Signs of Leafhopper Infestation
Feeding
While the feeding damage from leafhoppers depends on the plant and the leafhopper species, there are some common traits: As the leafhoppers suck the sap or juice out of the leaves, the transport of water and nutrients in the leaves are disrupted. As a result, the leaf margins or entire leaves turn light and pale, or brown, and eventually dry out. Leaves can also get white stippling and later white blotches. Leafhopper feeding can also lead to tip burn, curling, and stunting of leaves. Leafhoppers are not the only culprits that can damage leaves, so to be sure, also look for tiny dark spots on the underside of leaves, which are leafhopper excrements. Some leafhoppers also secrete honeydew, which then leads to the growth of sooty mold on the leaves.
Cast Skins
Check the underside of leaves for the cast skins that the nymphs shed when they molt.
Disease
Some leafhopper species transmit destructive plant diseases such as curly top virus and aster yellows. It is possible that your plants show signs of the disease without you seeing the leafhoppers themselves.
Predators
Luckily there are many beneficial insects that love to feast on leafhoppers. If you spot lots of ladybugs, big-eyed bugs, lacewings, minute pirate bugs, or parasitic wasps, take a close look where they gather as you might find a leafhopper infestation.
What Causes Leafhoppers
Some leafhoppers are native insects while others were brought in from overseas. Whichever leafhopper species is descending upon your yard, the insects are in search of their preferred foods. If those are not available, they will go after alternatives with fresh, succulent leaves and even weeds. The leafhopper species that do not overwinter in warm climates as adults or eggs migrate from the southern states up north in the late spring. Areas with lots of agriculture naturally attract leafhoppers every year and chances are that some leafhoppers will eventually also visit your yard.
How to Prevent Leafhoppers
If you had a leafhopper infestation in your neighborhood in the previous year or if you live near a vineyard or a farm, it is likely that leafhoppers will come back next year, and you should take preventative measures. In addition to putting up floating row covers, as described above, dusting susceptible plants with diatomaceous earth makes the leaves less palatable to leafhoppers. In warm climates where leafhoppers overwinter as eggs, check protected areas such as the bark and twigs of trees and rose canes. The eggs are inserted into the bark crevasses and appear as pimple-like swellings. Thoroughly remove the egg masses and dispose of them in the garbage.
