Larimer County CSU Extension Master Gardener
My vegetable garden is getting eaten by grasshoppers! They are only eating some of my plants right now, but they are eating them fast and I see them everywhere. How can these hungry insects from killing all my plants?
A: There seem to be high numbers of grasshoppers this year, but populations fluctuate from year to year depending on a variety of environmental factors. Grasshopper problems increase in the early summer and can continue until a hard frost. In the vegetable garden they tend to prefer lettuce, carrots, beans, sweet corn and onions, but typically don’t bother squash, peas and tomatoes. There are different sprays, dusts, and baits available. Carbaryl (Sevin) can be used on a variety of fruits and vegetables, and can often be used up until harvest time. Acephate (Orthen) should only be used on non-edible crops. Permethrin is widely available for garden use on vegetables and fruits, but remains effective for a shorter period of time. Nosema locustae (NOLO Bait, Semaspore) is only effective against young grasshoppers and is slow acting, but it is allowed in Certified Organic crop production and only kills grasshoppers. For any pesticide, read the label carefully and apply only as directed.
Many of these products can be purchased at your local garden supply store. Some can be added directly to the plants, and others are best used on the perimeter of the garden or in the area around the beds. These chemicals may have to be reapplied after rain or watering. It is better to get the grasshoppers when they are still young and before adults begin migrating. Other methods for controlling grasshoppers include screening, encouraging birds in the garden, letting poultry run loose and controlling grasshopper breeding sites.
For more information on Grasshopper Control, please visit http://www.ext.colostate.edu and read CSU Extension Fact Sheet #5.536.