Differential grasshopper nymph.
In This Issue:
In the Spotlight: Getting Chemicals into Trees, Part II
In the Spotlight: Grower Profile, Weeks Berries of Paradise
Indoxacarb for Alfalfa Weevil
Springtail Into Summer
New Honey Bee Resources
The Search for Brown Marmorated Stink Bug
Root-knot Nematodes on Vegetables and Ornamentals
In the National News
Watch out for young grasshoppers jumping around your landscape, garden, and crop fields. Large numbers of immature grasshoppers have been spotted in some locations in Utah this spring. The best time to control grasshoppers is when they are young, before they have wings and can fly away from insecticide treatments. For best results, organize your neighborhood or local farming/ranching community to work together to treat larger tracts of land. Treating as wide an area as possible is a key to success.
In the late summer and fall, adult female grasshoppers lay their eggs in pods in undisturbed soil. Open fields, roadsides, weedy areas, rangelands, and boundaries between open space and residential lots are common grasshopper egg-laying sites. The eggs hatch the following spring and the immature grasshoppers, called nymphs, crawl and hop to find green plants to eat. As temperatures warm, soil moisture declines, and unmanaged plants dry down; grasshopper nymphs move into home yards and gardens, and agricultural fields to seek green forage. The best time to treat is in the early summer as nymphs move from open to cultivated land, and before the nymphs develop into winged adults (click here to see diagrams on distinguishing grasshopper nymphal stages).
|Grasshopper feeding injury.|
There are three main insecticide formulations, or types, to treat grasshoppers: baits, dusts, and sprays. Baits are a mixture of an attractive food source, such as wheat bran, plus an insecticide. Common baits contain carbaryl, a carbamate insecticide, or spores of Nosema locustae, a natural grasshopper pathogen. Spread the bait evenly throughout the habitat. They must be reapplied approximately weekly, and immediately after wetting events, such as rain or irrigation. Baits are selective in that they only kill grasshoppers and other foraging insects (N. locustae will only kill grasshoppers). The primary dust product available contains carbaryl. Dusts have short residuals, and must be reapplied approximately weekly and after wetting events.
Both baits and dusts are easy to apply, but moderately expensive. There are numerous insecticide sprays with efficacy against grasshoppers, including malathion, carbaryl, permethrin, and bifenthrin. An insect growth regulator, diflubenzuron (Dimilin), is available for commercial-scale applications. Sprays are less expensive than baits and dusts, but require a sprayer suitable to the situation and scale of the application. Sprays will kill on contact, or when grasshoppers eat the treated foliage. Check all product labels for allowed application sites. For example, some insecticides can be applied to ornamentals, but not to edible plants.
For urban sites, apply insecticides along the borders of residential properties, and for a distance into the open and irrigated lands on either side of the border. There isn’t a threshold established for urban lands, but USDA recommends that treatments begin when nine or more grasshoppers are found per square yard on rangelands. A threshold for cultivated lands, including urban and agricultural would likely be lower. If possible, apply a border treatment to all contiguous properties along their interface with open lands. Join together with neighbors to increase the size of the area that is treated for best results. Another option for sensitive edible plants, such as vegetables and herbs, is to cover them with floating row cover to exclude grasshopper feeding. Covers on vegetables that require insect pollination, such as squash, must be opened during the morning hours when pollinators are most active to ensure good fruit set.
For grasshopper-infested agricultural lands and private rangelands, the Utah Department of Agriculture and Food (UDAF) and USDA Animal and Plant Health Inspection Service have sponsored a cost-share program in past years. Clint Burfitt, UDAF Entomologist, is the contact for information on grasshopper and Mormon cricket surveys and control program.
For more information on community-wide grasshopper control, check out the USU Extension fact sheet.
-Diane Alston, Entomologist
Featured Picture of the Quarter
A honey bee colony may collect up to 125 pounds of pollen in one year. When pollen is scarce, such as in early spring, bees have been known to collect other materials that look like pollen, like sawdust, rotted wood, coal dust, or fine soil. This bee was seen collecting fine coffee grounds from a compost pile in early March. The bee has packed the coffee into her corbiculae (pollen baskets) on her hind legs to carry back to the hive.
Pollen is the source of protein and lipids, minerals, and vitamins for bees. Some beekeepers provide artificial materials when pollen is in short supply.
-Image by Jim Cane, USDA Agriculture Research Service, “Logan Bee Lab”