What's Bugging You? Leafhoppers
Leafhopper (Cicadellidae)
If you happen to own a Virginia Creeper vine you have probably already had to deal with leafhoppers. The pesky little devils love Virginia Creeper, Engelmann Ivy, Green Ash trees and Canola. They also love many other plants (weeds included!) and really are not fussy as to what they feed on. The winged adults and the wingless nymphs like to feed from the underside of leaves and easily fly or jump if disturbed. They rarely attack plants with thick, waxy foliage.
Leafhoppers are very tiny (6mm), brown, grey or green, have a narrow body that is tapered at the end with strong back legs and sucking mouthparts. The feeding on the underside of the leaf produces a light colored stippled effect on the leaf surface. This can lead to some of the leaves yellowing and subsequently leaf death. Leaf damage is usually minimal but if infestations occur from year to year, the affected plant will eventually weaken to the stage any infection and disease can easily take over.
There are about 2,500 species of leafhopper in North America, and 22,000 species all over the world! In early spring, the winged adults migrate to our prairies on the winds from the southern states bordering the Gulf of Mexico and the Great Plains, U.S.A.
In early spring, the adults mate and the females lay translucent miniscule eggs in and on the underside of leaves. The wingless nymphs are yellow, brown or green. The adults and nymphs both suck out leaf chlorophyll, producing the stippling upper leaf damage that is seen about mid- summer. The nymphs pass through five stages in 4-6 weeks after hatching. Adults can live for months. Depending on the weather conditions and the species they can produce one to three generations per year. The adults will lay eggs again in the fall. A very few make it through the winter to hatch in spring. Any adults are usually killed by the winter cold.
The Six-Spotted Leafhopper (Macrosteles quadrilineatus) may carry and transmit a plant disease called Aster Yellows Phytoplasma. This leafhopper is grey/green in color and has 3 pairs of black markings on the forehead. While not as prevalent in the urban garden, this disease can be harmful to canola crops. It is only spread via the infected insects. Currently there are no controls in place for Canola infected with Aster Yellows but monitoring and research is ongoing. The leafhoppers will feed on infected plants. Once the pathogen is digested, it takes time to circulate in the leafhopper body (10 to 21 days) and then travels to the insects salivary glands. They then transfer the pathogen by feeding on healthy plants. The infected adult will carry this disease all its life. Infection is more prevalent in a wet season than a dry one. Fortunately, not all Six-Spotted Leafhoppers will become infected in a growing season. Only 1-5% of the population will carry the disease.
Aster yellows will cause a plant to grow very fast or stop growth all together. Flowers will be malformed and come out as green plant tissue. Carrots, beets, celery and lettuce can be affected. Tuberous vegetable plants will grow tons of root hairs or become discolored and/or disfigured. It can overwinter in the roots of perennial plants as well.
To stop aster yellows in the garden, one has to interrupt the leafhopper life cycle. This is done by removing the affected plants – cleanliness is key and weeding must be kept up during and after the growing season.
Encourage good bugs to stay in your garden by providing them with an insecticide free environment. Bugs that eat leafhoppers are damselflies, ladybugs, spiders, predatory mites, and lacewings. Be familiar with what these insects look like and avoid killing them! Birds and lizards will also eat leafhoppers.
Do not use high nitrogen fertilizers excessively during the growing season. This causes new tender growth and makes feeding easier for the leafhoppers and their nymphs.
Place yellow sticky traps near or behind vines that cover pergolas, arbors or walls. The downside to this method is that you will have to replace them after a rain.
Homemade detergent based sprays or environmentally friendly soaps are not recommended as they will kill the leafhoppers and the good bugs as well. However, if you do have a huge leafhopper infestation you can use insecticidal soap early in the morning or late in the evening. Follow label directions carefully and be sure to wear a hat and protective clothing.
The best method to keep the leafhopper numbers down is to spray your vines routinely with a blast of water. Spray behind the vine as well and amongst the branches where they hide. Surprisingly, this removes many bad insects such as aphids, mites, and adult/ nymph leafhoppers. Once knocked to the ground, they cannot feed. Timing water sprays with the nymph stages is impractical and virtually impossible, so just spray routinely whenever you have the hose out in the garden.