JoAnne Skelly: Leafhopper invasion

In the last week, leafhoppers have invaded our house both inside and out. Suddenly I’m seeing dozens of brown wedge-shaped insects crawling all over my windows and screens. They are even on the kitchen walls. These annoying critters, also called planthoppers, are less than a 1/4-inch long, and they keep me busy squishing them each day. I decided to find out more about them.

Leafhoppers belong to one of the largest families of plant-feeding insects with approximately 20,000 currently described species. More species are being discovered almost daily. Some entomologists suspect there may be 100,000 species in the world. They are near relatives of cicadas and distant relatives of aphids.

Females lay eggs in plant tissues such as leaves. These eggs may stay dormant for up to a year, or develop and hatch in a few weeks. Young leafhopper nymphs molt (shed their exoskeleton) five times before becoming adults. Most leafhoppers live only for a few months; but there may be several generations per year. Some species can overwinter in protected places such as bark crevices, walls, etc., and others migrate south.

Leafhoppers are plant feeders with piercing-sucking mouthparts. They insert their needle and straw-like mouthparts into a plant and then suck the sap out. While they are feeding, they usually infect a plant with a virus, causing long-term damage or death to the plant. These viral infections rarely have a control, so farmers can incur significant economic losses. Leafhoppers are pests in grapevines, beets and other agricultural crops. Home gardeners can lose many garden plants too. Since these insects hop, move rapidly and also fly, they are hard to control with an insecticide.

The damage from leafhopper feeding looks like small white spots on the upper surface of leaves. These spots may grow together causing larger blotches on mature leaves. Sometime leaf margins will dry up and eventually the whole leaf may turn brown. Growing tips may be stunted and deformed.

I suspect the surge in leafhoppers is what the University of California Cooperative Extension Master Gardeners call “transitory insect invasion.” These insects are on the move because it’s the end of the season. They are migrating from host plants now that their food source has dried up. It’s simply a matter of chance where they settle. I was just lucky they came to our house. I will keep on squishing them or using the vacuum to eliminate them. Soon they will be gone, until next spring.

JoAnne Skelly is Associate Professor & Extension Educator, Emerita at University of Nevada Cooperative Extension. She can be reached at skellyj@unce.unr.edu.