Deb Babcock: Grasshopper problems in 2010
June 14, 2010
Steamboat Springs — The Routt County Cooperative Extension Office fielded many reports of grasshopper infestations toward the end of the growing season last year.
Infestations were particularly bad north of Steamboat Springs toward Clark and Hahn's Peak, as well as south of town, along Colorado Highway 131 heading toward Oak Creek and Stagecoach.
Each year, it seems the Yampa Valley has infestations of several varieties of grasshopper, each with a different life cycle. Needless to say, it is a challenge for gardeners to control damage to their plants from these voracious pests.
Since grasshoppers tend to infest an area for a three- to four-year cycle, chances are that different parts of the valley can expect to see repeat infestations that started in previous years, while other parts of the valley will notice a lessening of the pests.
If we experience some dry, warm spring days that cause grasshopper eggs to hatch, followed by some cool, wet days that will kill off many of the hatchlings, the grasshopper problem might be lessened. But, of course, we cannot count on that.
So, what can home gardeners do to lessen 'hopper damage to our prized plants?
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Keep an eye out for grasshoppers hatching. They will be crawling along the ground, not hopping. It's easier and more efficient to try to control grasshoppers when they are young. At those early larval stages, they are more concentrated and it's possible to treat a smaller area and still get good control.
A microbial insecticide, known by trade names including Semaspore and NoLo Bait, only is effective against these young grasshoppers. Microbial insecticides take about two weeks to begin effectiveness and must be purchased fresh and used right away.
The products have a shelf life of only 90 days.
Young grasshoppers eat this bait and spread disease to other grasshoppers. While individuals have had success with these products, controlled research studies have shown only 30 to 40 percent effectiveness at reducing grasshoppers, at best. What's good about this product is it only works on grasshoppers and some crickets — not birds, bees or butterflies.
As grasshoppers mature and start heading toward your garden, insecticide treatments will have limited success since there is continual reinvasion by grasshoppers and the product wears off relatively quickly.
A bran-bait product called EcoBran was tested by many local master gardeners several years ago, with pretty good success. It targets immature and mature grasshoppers and contains the insecticide carbaryl, integrated in bran flakes that are spread on the ground. What I particularly like about this insecticide is its fast-acting effectiveness — I had overnight results — as well as its relative safety. Bran baits are more effective at controlling grasshoppers than the bacterial insecticides mentioned above.
The dry bran flakes are pretty much a grasshopper-specific killer. The liquid forms of grasshopper insecticide — acephate, or Orthene; carbaryl, or Sevin; and malathion — that are sprayed directly on your plants also are effective but will harm beneficial bees, flies, butterflies and hummingbirds who drink plant nectar from sprayed plants. Liquid insecticides also leave on edible plants a residue that can be harmful to humans. It's best to spray these insecticides at night or early morning, when bees, flies and butterflies are less active. Always read and follow label instructions.
Be on the lookout for hatching hoppers this spring, so you get the jump on them before they get the jump on you.
Deb Babcock is a master gardener through the Routt County Cooperative Extension Office. Call 970-879-0825 with questions.