Watch out for grasshoppers
Grasshoppers can be pests in home gardens. Of the different species that occur in Minnesota, there are only a few kinds that are particularly common in the home landscape. These would include the two-striped grasshopper, the redlegged grasshopper, and the differential grasshopper.
Grasshoppers spend the winter as eggs that were deposited into the ground the previous year. These eggs are banana-shaped and laid in a cluster. These eggs are usually deposited in fields, preferably in undisturbed sites. From May until mid-June, these eggs hatch into immature nymphs. These young grasshoppers look just like adults except that they are much smaller and lack wings.
Grasshoppers damage plants by chewing holes in the leaves. Eventually the whole leaf or even the entire plant can be consumed. They prefer to eat grasses and are commonly found in prairies and meadows. However, gardens are also subject to grasshopper feeding where essentially any green plant is fair game. If populations are high enough even houses aren't safe as grasshoppers can damage nylon screens and masonite siding.
Managing grasshoppers can be very challenging. Exclusion is an option, although it probably isn't practical for your entire garden. You can protect valued plants by using floating row covers made of spun fabric. Be careful with plastic row covers as grasshoppers have been known chew through them. You may also consider protecting your plants with metal screening.
Insecticides are an option, although the more numerous grasshoppers are the more difficult it is to manage them. When you treat garden plants, they will still endure some damage before grasshoppers are killed. Even if you succeed with the grasshoppers in your garden, they are very mobile and more can fly into your yard. If you are finding grasshoppers on many plants, you may need to be selective in which you plants you try to protect. There are a variety of garden insecticides available, including products containing esfenvalerate, bifenthrin, permethrin, deltamethrin, cyfluthrin, acephate, or carbaryl. Be sure that the product you wish to use is labeled for the plants you want to treat.
Published in Yard & Garden Line News, July 15, 2006