Quick answer: Leafhoppers are small, wedge-shaped insects, about 1/8 to 1/6 inch long, that jump or fly when disturbed. Most species found on hemp and cannabis cause little or no visible damage. The potato leafhopper in the eastern United States can cause hopperburn, a yellowing that starts at leaf tips, so scout leaf undersides and check yellow sticky cards.

What Do Leafhoppers Look Like?

Leafhoppers are small insects, about 1/8 to 1/6 inch long, with an elongate body. The adults are winged and readily jump and fly from plants when disturbed. The immature stages, called nymphs, are wingless but can quite actively crawl on plants.

The UC Statewide IPM Program describes adults as wedge-shaped and relatively long compared with their width. They’re commonly brown, gray, green or yellow, or a mottled mix, and they walk rapidly sideways or readily jump when disturbed. One or more long rows of small spines along each hind leg set them apart from some similar-looking insects that suck plant juices.

Where to Find Them on the Plant

Adults, nymphs and the pale cast skins that nymphs leave behind are generally found on the underside of leaves or on green shoots.

Leafhopper Life Cycle

Leafhoppers develop through 3 life stages: egg, nymph, and adult. Females insert their eggs into tender plant tissue, and the nymphs generally develop through 5 increasingly larger instars before becoming adults, with no pupal stage. Most species have two or more generations per year.

Which Leafhoppers Turn Up on Cannabis?

Colorado State University researchers note that leafhoppers are often the most species-rich insect family associated with hemp, though few appear to reproduce on the crop. Fourteen species have been identified in Colorado, and breeding seems to happen with only three or four of them. Most adults on the foliage appear to be transients, perhaps associated with weeds in the crop.

The species found most regularly in Colorado hemp is Ceratagallia uhleri, one of the few that can reproduce on the plant. No visible plant injury has ever been observed from this leafhopper. A small light green species tentatively placed in the genus Empoasca also reproduces on the crop. One rarely found species, the beet leafhopper, matters mainly because it can transmit beet curly top virus to hemp.

Farther east, the picture changes. The potato leafhopper (Empoasca fabae) occurs in the eastern half of North America and doesn’t occur in Colorado. Colorado State University says it may do more serious damage to hemp than any other leafhopper associated with the crop. It’s recorded from hemp in Tennessee and Virginia, although the 2019 review found no signs of hopperburn there.

Leafhopper Damage on Cannabis

Most leafhoppers on hemp feed on fluids moving through the phloem, which has insignificant effects on plant growth and leaves no visible symptoms. A few, such as an Empoasca species in eastern Colorado, extract fluids from mesophyll cells and leave a small, light flecking injury called stippling.

Stippling

Stippling looks like bleached specks on the leaf. Because lace bugs, plant bugs, spider mites and thrips can also discolor leaves, the UC Statewide IPM Program suggests examining the underside of leaves for the arthropods themselves.

Hopperburn

Hopperburn is the potato leafhopper’s signature. Symptoms typically start as yellowing at the tip of leaves, which may spread to the entire leaf and be followed by areas of leaf death. Leaf curling may also occur. On hemp, the damage seen so far is yellowing of the tips of leaflets and, perhaps, progressive leaf necrosis.

The cause is how this insect feeds on phloem cells. Its saliva further damages them, which disrupts nutrient movement so sugars accumulate in the leaves. If the yellowing doesn’t look like hopperburn, compare it with 8 common cannabis deficiencies by leaf symptoms before blaming insects.

Large numbers leave other clues. Leafhoppers excrete honeydew on which blackish sooty mold grows, and nymphs leave whitish cast skins on the underside of foliage as they molt.

Are Leafhoppers Bad for Cannabis?

In most cases, no. Colorado State University reports that none of the leafhoppers found in Colorado hemp produce feeding injuries capable of causing any significant damage. The situation is different in the eastern United States, where the potato leafhopper is present.

Even there, the impact isn’t settled. Colorado State University describes the importance of potato leafhopper and hopperburn to hemp as unknown. It expects the response to injury to vary among hemp cultivars, as it does with other crops, and notes an Indiana field that suggests there may be genetic differences in hemp to hopperburn.

For home gardens in general, the UC Statewide IPM Program says leafhoppers are usually just an annoyance or curiosity that don’t threaten plant survival, and generally no control is needed.

How to Check Cannabis for Leafhoppers

1. Turn leaves over. Look for adults, nymphs and pale cast skins on the underside of leaves and on green shoots.
2. Hang yellow sticky cards. Colorado State University says beet leafhopper in hemp can be monitored with yellow sticky cards placed on the field edges, inspected weekly and replaced as needed.
3. Sweep larger plantings. Sweep nets are another survey tool in hemp fields, and adults of about a half dozen leafhopper species have been collected from hemp in sweep net samples.

Identification matters because several species can share a planting. Colorado State University stresses accurate identification, since other leafhopper species may be present alongside the one that causes problems.

How to Keep Leafhoppers in Check

Young plants are the most susceptible to beet curly top virus infection, so Colorado State University suggests placing a physical barrier over seedlings where beet leafhopper is a concern. Scouting nearby crops and weeds is also recommended.

Leafhoppers have many natural enemies, including assassin bugs, lacewings, damsel bugs, lady beetles, minute pirate bugs and spiders, and some species are attacked by parasitic wasps. The roundup of beneficial insects cannabis growers commonly use covers several of these.

Weeds in and around the garden are worth managing, too. Most leafhoppers on hemp foliage appear to be transients, perhaps associated with weeds, and the UC Statewide IPM Program notes that, for leafhoppers that feed on many different plant species, removing weed hosts can reduce the abundance of leafhoppers that migrate to garden plants. Other outdoor pests, from crickets to grasshoppers, are covered in protect marijuana plants from pests and bugs.

Frequently Asked Questions

Do Leafhoppers Damage Cannabis Plants?

Usually not much. Colorado State University reports that very little, if any, damage appears to be associated with the leafhoppers found in hemp, apart from modest stippling from one Empoasca species. The exception to watch is the potato leafhopper in the eastern United States, which can cause hopperburn, a yellowing that starts at leaflet tips.

What Is Hopperburn on Cannabis?

Hopperburn is a plant reaction to potato leafhopper feeding. It typically shows as yellowing at the tip of leaves that can spread across the leaf, followed by areas of leaf death and sometimes curling. On hemp, Colorado State University has seen yellowing of leaflet tips and, perhaps, progressive leaf necrosis.

How Do You Tell Leafhoppers From Other Small Insects?

Watch how they move and look at the legs. Leafhoppers are wedge-shaped, walk rapidly sideways and readily jump when disturbed. The UC Statewide IPM Program notes that one or more long rows of small spines along each hind leg distinguish them from some similar-looking insects that suck plant juices.

Where Do Leafhoppers Hide on Cannabis?

Check the underside of leaves and the green shoots. That’s where the UC Statewide IPM Program says adults, nymphs and their pale cast skins are generally found. Adults jump or fly off when disturbed. To monitor beet leafhopper in hemp, Colorado State University says yellow sticky cards can be placed on the field edges.

Do You Need to Get Rid of Leafhoppers on Cannabis?

Often not. The UC Statewide IPM Program says leafhoppers in gardens are usually just an annoyance or curiosity, and generally no control is needed. Keep scouting, though. If leaflet tips start yellowing in the eastern United States, potato leafhopper and hopperburn are worth ruling in or out.

How Big Are Leafhoppers?

Leafhoppers found on hemp are about 1/8 to 1/6 inch long, according to Colorado State University, and the UC Statewide IPM Program says adults are commonly less than 1/4 inch long. Larger relatives called sharpshooters can reach about 1/2 inch.

Sources

• Colorado State University, Hemp Insects: Leafhoppers
• Colorado State University, Hemp Insects: Potato Leafhopper and Hopperburn Disorder
• Colorado State University Agricultural Biology, Beet Leafhopper and Beet Curly Top Virus (IPM Pests)
• Cranshaw et al., Colorado State University, Developing Insect Pest Management Systems for Hemp in the United States (Journal of Integrated Pest Management, 2019)
• UC Statewide IPM Program, Leafhoppers (Home and Landscape)