Grape
Rose Chafer
Macrodactylus subspinosus
Insect
In a Nutshell
- Feeding holes in flowers and leaves.
- Skeletonizing of leaves.
- Fruit can also be damaged.
Can also be found in
Grape
Symptoms
Symptoms are different depending on which crop is affected. On roses the flower blossoms are affected, causing large irregular shaped holes in the flower petals. On fruit trees, especially grapes leaves are fed on, eventually skeletonizing them. Also the fruit can be damaged, being partly peeled and gouged in irregular shallow patches.
Recommendations
Organic Control
Drench the soil with a parasitic nematode to kill the larvae. Pyrethrin is recommended if infestation levels are severe.
Chemical Control
Always consider an integrated approach with preventive measures together with biological treatments if available. Pesticides that are recommended contain acephate, chlorpyrifos, bifenthrin, cyfluthrin or imidacloprid. Avoid spraying on flowers to not harm or kill honey bees.
What caused it?
The damage is caused by the adult chafer of Macrodactylus subspinosus. They are pale and slender green colored beetles with a darker head and long legs, ca. 12 mm long. The female bug lays her eggs just below the soil surface in sandy, well-drained soils with grass. Wetted soils are more preferred for laying eggs. Larvae overwinter as grubs in the soil and feed on grass roots. It affects roses, stone fruit trees, e.g. grapes, apples, cherries, peaches, pears and plums and prefers sandy soil.
Preventive Measures
- Monitor your crop twice a week for the beetles and feeding damage.
- If the number of rose chafers is relatively small, remove the pest by hand and put them in a bucket with soapy water.
- Place physical barriers cheesecloths or floating row cover in your vineyard, that will help to protect your crop from the adult but not the grubs that live in the soil.
- Set up pheromone traps away from the vineyard.
- Eliminate larvae hibernating sites by plowing the soil.
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