Garden Help Desk: Follow these steps to reduce grasshopper damage in the garden
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- Once grasshoppers are mature, they are more difficult to control with insecticides. Controlling grasshoppers while they are young means fewer eggs laid at the end of the gardening season.
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- Young grasshopper nymphs may be easily overlooked or may not cause concern because they don’t seem large enough to do much damage. Young nymphs become large grasshoppers that are less susceptible to control measures.
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- Grasshoppers have many natural enemies. This praying mantis is one predator that is large enough and fast enough to grab an unsuspecting grasshopper.
Our neighborhood seems to be overrun by grasshoppers. What can we do to get rid of them this year?
You don’t say whether your neighborhood is a subdivision with small lots or in a more rural setting with larger properties near fields, pastures and country roads. Each setting has different issues to consider.
It won’t be possible to completely eradicate the grasshoppers, but there are some things you can do to keep their population low and protect your landscape.
Working together with your neighborhood is a first step to success in protecting your landscape. Grasshoppers are very mobile, especially as they become more mature. You might manage to kill the ones you see in your yard, but there can be more in the surrounding area to take their place. The more neighbors you can recruit to the project and the wider the area of your control measures, the more successful you’ll be.
Control methods are most successful while grasshoppers are small nymphs. Once grasshoppers are larger and more mature, pesticides and biological controls are less effective. The grasshoppers you’re seeing this summer came from eggs that were laid last August, September and October. Eggs began hatching in late spring, and most of those eggs have hatched by now. Since the youngest grasshoppers are also the most susceptible to pesticides and diseases, the time during and shortly after the egg hatch season is the most important time for control methods. The longer you wait, the less likely you are to be successful.
Female grasshoppers prefer to lay their eggs in undisturbed soils, so landscapes close to drainage ditches, fields, rural roadsides and abandoned, neglected or weedy lots are more likely to have grasshopper problems. If you live near an area like one of these, you’ll need to pay special attention to control practices at your perimeters. Talk to your neighbors with property like these and encourage them to join your control program. You’ll also want to make sure you don’t let dry or weedy and neglected areas develop on your own property where you have control over how the landscape is managed.
Pesticide sprays and baits are the most common control methods. There are many readily available products with active ingredients that are effective. Baits are usually grain-based products that include a pesticide. The bait should be spread evenly throughout the area where you expect grasshoppers show up on your property.
Baits can be effective in open, dry, weedy areas where there isn’t as much plant life to serve as an alternate food source for grasshoppers. If your landscape borders properties like these, give those areas careful attention.
On smaller properties, like well-tended residential landscapes, sprays may be more effective than baits because grasshoppers can be attracted to the green landscape plants and ignore the bait. Well-tended landscapes are also irrigated regularly, and baits need to be refreshed after rain and irrigation, making them less convenient than spray products. Pesticides with the active ingredient zeta-cypermethrin, permethrin or bifenthrin should be effective. If you’re spraying in vegetable gardens, home orchards or around other edible plants, make sure you choose products that are labeled for use on fruits and vegetables. Read product labels and follow the directions.
Keep in mind that the pesticidal sprays effective for grasshoppers will also kill other insects, including the beneficial insects that help to keep grasshopper populations under control. Apply these products only as needed and follow the label directions.
Many gardeners want to avoid conventional pesticides in their landscape. In the past, they might have used a bait product that contains the protozoan Nosema locustae. The protozoan infects only grasshoppers and Mormon crickets. It isn’t quick acting, but its effects can be long lasting as infected grasshoppers die and are eating by other grasshoppers, who will also become infected. Unfortunately, this bait hasn’t been available for the past few years.
Row covers are a natural option for protecting plants in certain settings from grasshopper damage. Use insect-grade floating row cover or tulle fabric over your vegetable plants and small fruits plants to exclude grasshoppers. If you have plants like squash, pumpkins or others that need insect pollination, you’ll need to uncover those plants each morning for a couple of hours or hand-pollinate the flowers. Inspect your plants each time you’re ready to re-cover them and hand pick any grasshoppers that may have found your plants.
If you’ll recruit your neighbors, take a careful look around your landscapes, make a plan of action and be diligent this summer, you should be able to reduce grasshopper damage for the rest of the season.
