Grasshoppers in the Garden

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Grasshoppers show up in just about every garden. Photo: http://www.capjournal.com

They’re here, they’re there, they’re everywhere! Yes, grasshoppers do get around. There are some 11,000 species and they’re found all over the world except Antarctica and a few isolated islands. 

Grasshoppers are mostly ground-dwelling insects with strong hind legs that allow them to escape from their enemies by jumping. Although they can also fly, they usually do so only over short distances. And they are almost all herbivorous: i.e. they’re plant eaters. Therefore, they’re not a group of insects the average gardener is going to love.

The very simple life cycle of the grasshopper. Ill.: microcollegium.canalblog.com

From the time they hatch, usually in spring, they already resemble their parents, but in miniature, then grow by stages over the spring and summer to their full size. The bigger they are, the more they eat! In most climates, they only stop eating when frost kills them.

As they grow, their original food supply (often some sort of grass) begins to be overharvested and competition among them increases. That’s when they tend to start to leave their favorite haunts, fields and meadows, and move into gardens. In fact, some species they increase so much in numbers they form swarms and are then called locusts.

But I need to give grasshoppers their due: they’re a major food supply for birds, lizards, ground beetles, spiders and others, so are beneficial to the environment. And their excrement makes great plant fertilizer. Also, when they’re only present in small numbers, they do little serious damage to our gardens. 

Chewed leaves could have a lot of causes, but when grasshoppers are present, they’re the likely culprits! Photo: bugspray.com

Of course, when those numbers increase and you start to see chewed leaves and ragged holes, plus similar damage to stems and fruits, they’ll no longer seem so environmentally friendly. They’ve been known to wipe out entire crops, although more so in farmers’ fields than home gardens.

When Grasshoppers Go Overboard

Grasshopper problems in home gardens tend to be mostly outside of cities. Typically, the garden is surrounded by agricultural fields, meadows or natural grassland and at a certain point, usually in midsummer and especially in years of drought, they leave the fields and migrate to your carefully tended plants. 

They do have distinct preferences: first and foremost, grasses and cereals, including corn, wheat, rye, barley and rice, plus alfalfa and soybeans. When those are in short supply, they switch to other plants, including clover, lettuce, beans, carrots and onions. While they aren’t too fond of squash, peas and tomatoes, when they’re starving, there isn’t much they won’t eat, even attacking trees and shrubs.

What to Do When Grasshoppers Attack

Most grasshoppers are green or brown. They often change color as they mature. Photo: http://www.mtpr.org

Grasshoppers are very hard to control, so, at best, you can only expect moderate success.

Here are some methods of limiting their damage:

Keep nearby fields well watered. Well, you can only do that if they’re your fields, but grasshoppers will have no need to move into gardens if fields nearby are nice and lush. 

Try biological controls. Again, you have to be the owner of the fields where the grasshoppers spend their youth, but you can spread a fungus (Nosema locustae) over fields where they occur. When ingested, it causes them to stop feeding and eventually die. It’s most effective on young grasshoppers. Nolo Bait and Semaspore are two products containing this fungus. Another such fungus is white muscadine disease (Beauveria bassiana), sold as BioCeres WP, Myotrol and under other names. Other biological controls (bacteria, viruses, predatory flies and wasps, etc. are also being studied and may eventually become available.

Don’t expect to see these products in garden centers! They’re usually only available online from companies specializing in biological controls.

Place a perch here and there for kestrels: they love grasshoppers. Photo: 200723D Peter Brannon, Flickr

Encourage their enemies. Do everything you can to attract birds to your garden (feeding stations, nesting boxes, bird baths, etc.). Even otherwise unappreciated birds like starlings, house sparrows and grackles are great predators of immature grasshoppers. Grasshopper sparrows, horned larks and kestrels love the adults. Free-range chicken, ducks, turkeys and guinea fowl are superb hunters of grasshoppers at all stages of their life, from egg to mature adult. 

As mentioned, ground beetles, spiders and praying mantises are also among the grasshoppers’ predators. You can release praying mantises, for example, and thus increase their numbers. Do note, though, if you have fowl running loose, they’ll eat all of the above.

All sorts of grasshopper-controlling microbes and parasites (bacteria, fungus, viruses, etc.) live in undisturbed soil, so no-till gardening can be helpful to a certain degree.

Treat with Pesticides. Most of the pesticides a farmer would use against grasshoppers, like carbaryl, malathion and acephate, are either not available to home gardeners or not something you would want use in a home garden, notably one where you grow vegetables. Permethrin is possibly more acceptable, being less persistent, while neem, diatomaceous earth, kaolin clay, insecticidal soap and hot pepper wax are organic and fairly effective if used at the right times. Some gardeners swear by garlic spray as a grasshopper repellent while others have no luck with it. 

Keep weeds down. Many weeds are favorite grasshopper foods, so removing them will make your garden less attractive to grasshoppers.

Put in a grass hedge. Surrounding your garden with tall grasses—and keeping them well watered!—can be helpful, as they’ll keep grasshoppers occupied.

Floating row cover. Photo: Lee Valley Tools

Use floating row cover. Protect specific crops with floating row cover. You don’t usually need to support this kind of row cover: as the name suggests, it’s supposed to “float” overtop the plants, resting on their upper leaves. However, where foliage touches the fabric, grasshoppers have been known to gnaw their way through to reach it, so raise it above the plants on hoops and stakes. Or try impossible-to-chew aluminum screening.

Grow Plants Grasshoppers Don’t Like. All the above methods are fine in areas where grasshoppers are just an occasional annoyance, but where they’re a serious problem every year, the only logical solution is to switch to plants they don’t like. 

Since there are many species of grasshopper and each will have its preferences, plants they don’t like will likely vary from one region to another. You’ll soon start to learn on your own which plants they tend to ignore under your conditions. However, the following plants are said to be ones grasshoppers will generally avoid, so you might want to start with them: 

  • Artemisia
  • Calendula
  • Cilantro/coriander
  • Crepe myrtle
  • Forsythia
  • Jasmine
  • Juniper
  • Lilac
  • Moss rose (Portulaca)
  • Pea
  • Pink (Dianthus)
  • Sage
  • Salvia
  • Squash
  • Tomato
  • Verbena

For most gardeners, grasshoppers are only going to be an occasional problem, but those who have a recurrent problem with them have their work cut out for them. They are really very hard to control!

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