Printer-friendly .pdf version of this page
Heather Grab, SIPS – Cornell University & Marion Zuefle, NYS IPM Program
Many insects are associated with hemp in NYS though few cause concerning levels of damage. Pest insects differ among market classes (fiber, grain, cannabinoid) and production environment (protected culture vs open field) so regular scouting and identification are key.
Four-lined Plant Bug
Adults feed on leaves causing rounded brown spots. Active from May-July.
Pest Concern: Seedling most at risk from heavy feeding pressure.
Tarnished Plant Bug
Adults feed on developing leaves and flower tissue. As leaves expand, they show a ragged, deformed pattern. Reducing weeds like daisy fleabane and planting away from crops like alfalfa can keep populations low.
Pest Concern: Moderate
Japanese Beetle
Adults will skeletonize leaves and larvae feed on roots. They have many hosts. Large numbers can defoliate plants. Active July – August.
Pest Concern: Cause more damage on cannabinoid-free plants.
Flea Beetle
Adult feed on leaves and larvae feed on roots. Active June – Early September.
Pest Concern: Seedlings most at risk from heavy feeding pressure.
Potato Leafhopper
Adults and nymphs feed on underside of leaf causing tips to become yellow termed ‘hopper burn’. Often come in from adjacent crops like alfalfa.
Pest Concern: High pressure years have shown yield loss. Avoid fields near other host crops.
Two-spotted Spider Mites
Mites will feed on underside of leaves causing speckling. Thrive in hot dry conditions and have multiple hosts.
Pest Concern: Moderate, depending on weather.
Corn Earworm
Adults lay eggs on hemp, larva hatch and feed on maturing buds and seed heads. Monitor population ith pheromone trap.
Pest Concern: Moderate- High depending on pest pressure.
Cannabis Aphids
Aphids will feed on underside of leaf. Feeding can result in distorted flowers and development of sooty mold.
Pest Concern: Moderate
European Corn Borer and Common Stalk Borer
Larvae bore into stem causing stems to break. Monitor for corn borer with pheromone traps. Avoid weedy hosts for stalk borer.
Pest Concern: Borers are protected once inside plant, therefore, monitor flights and avoid weedy hosts.
Beneficial Insects
Lady bird beetles
Adults dome shaped usually pink or red with black spots. Larvae are black and orange and alligator shaped. Feed on aphids, pest eggs, and small
larvae.
Lacewings
Immature is cream and brown with large piercing mouth parts, will feed on aphids, mites, pest eggs, and larvae.
Bees and Hoverflies
Bees and hoverflies are important pollinators that collect pollen from male hemp flowers. Hoverfly larvae feed on aphids.
