insects and mites

Image of Asian lady beetle on hemp plant Asian lady beetles are often found in hemp fields. They feed on aphids and other soft-bodied insects.
Image of lady beetle larva on hemp plant The larva (immature form) of lady beetles are also predators, feeding on aphids and other soft-bodied insects.
Image of spider mites web on hemp plant Spider mites are often found in controlled environment production, but do exist in outdoor production. These pests cause webbing on the plant. There are natural enemies that attack this pest and can be purchased. This includes predatory mites and lacewings.
Image of spider mites on a hemp plant
Image of a Eurasian hemp borer larva on a hemp stalk This pest can be observed attacking branches and stems of small diameters. We have observed it in both outdoor cannabinoid hemp and ditchweed/feral hemp. They bore into the stalk, where they remain protected until they emerge as adults. The larval and pupal life stages are completed within the plant.
Image of a corn earworm on a cannabinoid hemp plant Corn earworm have many host plants, including cannabis. They are found in the bud/flower tissue towards the middle or end of the growing season. Brown, dead plant tissue is often observed before the caterpillar is detected.
Image of hopper burn caused by potato leafhopper Potato leafhopper is one of many different leaf and planthoppers observed on hemp. This species can cause distorted leafs that appear yellow to brown at the tips. It is unclear how much damage this is causing in the plants.
Image of a honey bee approaching hemp plant's flowers Honey bees and other pollinators can be observed in populations where there are pollen-producing plants. They collect this pollen and use it as a source of protein.
Image of a zebra caterpillar on hemp leaf
Image of a lacewing larva on hemp Lacewings are predatory insects found feeding on soft-bodied insects and mites.
Image of a corn earworm on a grain hemp plant
Image of a bumble bee collecting pollen from a hemp plant

Many different insects can be found in hemp fields, however, not all of them are pests. Within the complex of insects and mites found in hemp, we can find pests, predators, parasitoids, pollinators, and incidental arthropods.

Colorado State University has detailed fact sheets for many pests and natural enemies found in hemp. Some pests that could be a concern for hemp growers will vary depending on the type of hemp produced (fiber, grain, or cannabinoid), the growing environment (indoor or outdoor), and the geographical location of the field(s).

Indoor pests of concern include; cannabis aphids, rice root aphids, thrips, whiteflies, fungus gnats, hemp russet mites, broad mites, and spider mites. Hemp appears to be susceptible to typically greenhouse pests.

Outdoor pests of concern include; flea beetles, corn earworm, cutworms, cannabis aphids, hemp russet mites, spider mites, potato leafhoppers, Eurasian hemp borer, and European corn borer. Some pests are abundant in the field, but the damage is minimal. Just because you see damage does not mean you should immediately spray a pesticide product. In Indiana, we have a list of allowable pesticides that can be found here (PDF). If you see pest damage in your hemp, take clear photos of the pest and the damage, and collect specimens if possible. This will help diagnosticians identify the pest. Some pests may be easy to identify using guides, but a diagnostician or crop consultant may be needed for hard-to-identify pests. Purdue's Plant and Pest Diagnostic Laboratory provides pest identification for a fee and is an option for hemp growers. Many Land-grant universities offer similar services. 

There are natural enemies of pests found in hemp fields, which provide pest suppression. When managing pests in hemp, you should also consider natural enemies and pollinators when selecting pesticides. Indoor producers may buy commercially available beneficial insects and mites to release in their system. 

Additional Resources