Nothing ruins a perfect growing season like annoying pests. One week, you’re looking forward to a healthy yield of grapes, and the next, your grape vine has suffered enough damage to threaten a future harvest. It may seem like a hopeless endeavor, but there are ways to spot and prevent grape vine pests from ruining your harvest.
Keep reading to learn about 10 of the most common harmful grape vine insects and how to prevent them!
1. Grape Berry Moths
How to Spot Grape Berry Moths
Grape berry moths are small brownish-gray moths that are native to eastern North America. They are one of the most prominent grape vine pests in the eastern United States. After spending the winter in leaf litter among grape vines, the moths will then lay eggs on young grape stems. After hatching, the larvae will feed inside the grapes.
To spot grape berry moths, look for fruit that has ripened too early and shriveled. You will also see webbing from the larvae around the clusters of grapes. This often means that grape berry moths have fed on those specific grapes and hollowed them out. They also feed on the leaves and flowers of the grape vine, which raises the risk of rot forming on the vine.
How to Get Rid of Grape Berry Moths
If the infestation is not severe, simply remove affected grapes from the vine and properly dispose of them. In the wintertime, look for any leaves on the ground around your grape vine that have cocoons on them.
For heavier infestations, you can apply an insecticide before the point of grape veraison (when the grapes begin to change color).
2. Japanese Beetles
How to Spot Japanese Beetles
The Japanese beetle is another one of the grape vine pests you will see most often. Japanese beetles are brown and metallic green in color, and they feed on the foliage of a grape vine. With these pests, the leaves will often look like a skeleton, with only the leaf veins remaining.
How to Get Rid of Japanese Beetles
To get rid of Japanese beetles, hand pick them off the vine and put them into soapy water. If you have a smaller grape vine, you can cover it with cheesecloth to protect it from other beetles and pests.
3. Grape Mealybugs
How to Spot Grape Mealybugs
Grape mealybugs are pinkish-purple insects with segmented bodies, but they are usually covered in white wax. They range anywhere from 0.25-inches to a half-inch in size. These grape vine pests are predominantly in the Pacific Northwest.
Grape mealybugs lay eggs on grape vines and create a substance called honeydew. Honeydew is a sweet, sticky secretion that attracts ants and gives a place for sooty mold to thrive.
How to Get Rid of Grape Mealybugs
There are several different types of natural predators for the grape mealybug that should provide enough control for a light infestation. These natural predators include some types of lady beetles and Encyrtid wasps (parasitic wasps).
You can also thin excess foliage and fruit to keep from attracting these grape vine insects. For heavy infestations, use an organic insecticide early in the season such as Neem Oil.
4. Asian Lady Beetles
How to Spot Asian Lady Beetles
Do you remember those lady beetles I previously mentioned as a predator of grape mealy bugs? Well, come harvest time, Asian Lady Beetles can become grape vine pests. These beetles are copper-colored with a black “M” between their head and thorax. The “M” is what differentiates them from other lady beetles.
They hang around the vine feeding on different areas that have been previously damaged by other grape vine insects. This can become a problem for winemakers and other harvesters who remove clusters of grapes. The beetles hiding in the clusters get crushed with the grapes and give off a foul smell and bitter taste.
How to Get Rid of Asian Lady Beetles
To prevent Asian Lady Beetles from taking over later in the season, make sure to remove any damaged foliage or grape clusters that might attract these pests. You can also try to shake out any beetles when you remove a cluster of grapes.
Using insecticides isn’t recommended for these grape vine insects, as the chemicals will get on the fruit that will soon be consumed.
5. Grape Phylloxera
How to Spot Grape Phylloxera
Grape Phylloxera are very small insects with yellowish-green bodies. The phylloxera hide in the bark of the grape vine until springtime comes. At that point, the eggs hatch and they move onto the roots and budding leaves of the grape vine where they feed.
These grape vine insects cause small, abnormal growths on leaves called galls, which can lead to damaged crops and a stunted harvest if they form early enough in the season.
How to Get Rid of Phylloxera
Homeowners with small-scale gardens don’t usually need to treat phylloxera. The damage they cause is usually late enough in the season not to cause any harm. Repeatedly heavy infestations can be treated with an insecticide as the grape vine blooms.
How to Spot Leafhoppers
The leafhopper is a light yellow insect that is only about 0.12-inches long. This is one of the major grape vine pests in California. They lay their eggs on the underside of grape vine leaves. Once they hatch, they begin to feed on the leaves, which leaves behind yellowish-white spots. This leads to some leaves dropping altogether, and in turn, the grapes can get sunburned.
How to Get Rid of Leafhoppers
The best way to get rid of leafhoppers is through beneficial insects such as ladybugs and lacewings. It’s also a good idea to manually remove any infected areas and dispose of them properly. For heavy infestations, insecticidal soap can be applied to young leafhoppers early in the season.
How to Spot Cutworms
Cutworms are grayish-brown pests that look similar to a caterpillar, and they are usually around one inch long. At night, they feed on the buds of the grape vine, then they hide in the soil during the day.
This usually hinders the production of the grape vine, as it will send secondary shoots out to compensate for the damage. The secondary shoots are usually not as productive as the main shoots that the cutworms like to feed on.
How to Get Rid of Cutworms
Cutworms have many natural enemies, so beneficial insects and animals should usually take care of these grape vine pests before you have to step in.
During the wintertime, remove any brush or weeds that could serve as potential places for them to hide. Once spring arrives, don’t disturb the weeds, as that could make the cutworms come out of hiding and climb up the grape vine.
How to Spot Thrips
Thrips are yellow to brown in color with wings, but they are so small (0.04-inches) that you would need a magnifying glass to spot them. A good trick is to put a piece of paper under a leaf, then tap the leaf to see if anything falls onto the paper.
Thrips feed on the underside of leaves and suck the sap out of them. This causes noticeable spots on leaves. The damage caused by thrips is usually just a cosmetic issue and doesn’t cause harm to fruit production.
How to Get Rid of Thrips
Beneficial insects usually take care of thrips naturally. Weed control is also a good, natural way to prevent a thrip infestation. If the infestation of thrips is out of control, you can use Spinosad to control the population.
9. Spider Mites
How to Spot Spider Mites
Spider mites are tiny grape vine insects that feed on leaf cells similar to thrips. They spend the winter in weeds surrounding grape vines then move to the vine to feed in the springtime. This causes the leaves on the grape vine to turn yellow or bronze in color.
They usually do not cause enough damage to affect the fruit production of the grape vine, but heavy infestations could.
How to Get Rid of Spider Mites
Beneficial insects will usually take care of spider mites. For heavy infestations, apply an insecticide to the grape vine leaves during bloom time.
10. Yellow Jackets
How to Spot Yellow Jackets
From a distance, yellow jackets can look like honeybees. But, a run-in with a yellow jacket will be far worse than a run-in with a honeybee. Yellow jackets hide out in and feed on ripened fruit. At the end of the season, these grape vine pests look for sweet berries and grapes to eat.
They can repeatedly sting anything they see as a threat, and they are more aggressive than other bees and wasps.
How to Get Rid of Yellow Jackets
Pick any fully ripened grapes before yellow jackets have a chance to move in and feed on the fruit.
Wrapping Up Grape Vine Pests
Between common weed prevention and the presence of beneficial insects, a lot of grape vine pests won’t be a problem for you. But, sometimes – it just happens! Using the right prevention methods, you can save your grape vine harvest, or at least know what to do next year.
If you want to learn more about caring for grapes, we have several other helpful grape vine care posts for you!