Grasshoppers can do significant damage to rose plants. The insects tend to flourish in rural communities and on farmland, as they require relatively large, undisturbed areas to breed, but they can be found in urban areas as well. They breed in tall grass and weeds and feed on roses at night.
Grasshopper Life Cycle
Grasshoppers produce one generation a year. The eggs are laid in the fall and late summer and hatch the following spring. It takes 40 to 60 days for grasshopper nymphs to reach adulthood. Adult grasshoppers are voracious feeders and begin feeding on roses and other plants in July. The insects are capable of a lot of damage to foliage in a short amount of time.
Although grasshoppers only feed once a season, they leave a rose plant looking ragged. They eat the foliage of the plant, chewing along the sides of the leaves and leaving an irregular border. They may also eat into the center of new shoots, causing them to collapse, and may nibble rose buds, causing damage to the forming petals.
One method for removing grasshoppers from rose plants is to manually pick them off. This may decrease damage in minor infestations or when you have a small quantity of rose plants. Grasshoppers are most active at night. Using a flashlight, inspect the foliage of the plant. When you find a grasshopper, remove it and drop it into a container of soapy water. The soap in the water will prevent the insect from crawling out of the water.
If the infestation is major, with grasshoppers doing severe damage, or if you have a large number of rose plants, consider chemical controls. Insecticidal soaps that contain potassium salts of fatty acids as the main ingredient are labeled as effective against grasshoppers. Spraying the plants with a pesticide is another option. Contact your county extension office for pesticide recommendations.