Grasshoppers are among the most common insect invaders of Colorado yards and gardens and among the most difficult pests to control. For a variety of reasons, grasshopper populations cycle naturally from season to season, causing extensive damage during outbreak years. Annually, grasshopper problems tend to increase as summer progresses and usually continue even after the first frost. Grasshoppers favor certain vegetable plants such as lettuce, carrots and onions. They tend to avoid other vegetables such as squash, peas and tomatoes (leaves, not fruit). They usually avoid conifer trees and shrubs. During years when grasshoppers are extremely abundant and food is scarce, they feed on almost all plants. Grasshoppers generally don't feed on most trees and shrubs; however, these may provide convenient resting sites and grasshoppers often are found there. Grasshoppers may nibble on foliage and tender bark causing considerable injury over the course of a season. Established plants tolerate this leaf loss and usually recover and suffer little long-term injury. Grasshoppers breed and develop in dry, undisturbed sites such as pastures, empty lots and roadsides. As the plants in these areas dry out or are eaten, the grasshoppers move to lush growth found in yards and gardens. Grasshopper controls applied strictly to the yard will almost always achieve poor results because of problems with continuing reinvasion. Successful management of grasshoppers must include breeding areas as well as infested areas. Use of poultry has been very effective in reducing grasshopper numbers, but if it is not practical to have chickens or ducks in the area, an insecticide in spray or bait form can be used. Best results are realized when grasshoppers are treated when they are still small. The biological control Nosema locustae can be helpful for long-term control but because it works slowly, will probably not have immediate results so a combination of insecticide or bait and Nosema locustae is recommended. For information see the fact sheet, Grasshopper Control in Yards and Gardens.

Browse related Faqs by tag: horticulture, insects, colorado, grasshoppers