Mormon crickets are back for another summer, creating nuisances for some Nevadans. The Nevada Department of Agriculture says the Mormon cricket population is not expected to be too high, this year, but they are seeing infestations in northern Pershing County and southern Humboldt County, in rural areas around Winnemucca.
Mormon crickets have been a problem historically and over the last few years. Mormon crickets are flightless, ground dwelling insects native to the western United States. They eat native, herbaceous perennials (forbs), grasses, shrubs, and cultivated forage crops, reducing feed for grazing wildlife and livestock.
Mormon crickets can travel about a mile each day. They do not fly but they do climb. They do not bite, carry disease or pose a threat to animals that eat them. They do present some public safety issues on roads though.
Drought encourages Mormon cricket outbreaks, which may last several years (historically 5 to 21 years) and cause substantial economic losses to rangeland, cropland, and home gardens. This is particularly true as adults and nymphs of Mormon crickets migrate in a band, eating plants along their path.
Control efforts have increased in recent years as favorable conditions for the crickets have stimulated increased growth in their population. To reduce their numbers within communities and farmlands, and to provide for public safety along the Interstate 80 and Highway 50 corridors, the Nevada Department of Agriculture has applied Dimilin, a restricted use insect growth regulator, and baits containing the pesticide carbaryl (Sevin®) to thousands of acres for the past several years.
Mormon crickets are not true crickets; they are shield-backed, short-winged katydids that resemble fat grasshoppers that cannot fly. Adults and nymphs of Mormon crickets have long antennae and a smooth, shiny exoskeleton in a variety of colors and color patterns. Adult Mormon crickets are 1 ½ to 2 inches long.
Eggs are laid singly in the summer and are dormant through winter. Mormon cricket eggs hatch and nymphs emerge in the early spring when soil temperatures reach 40°F. Courting and mating begin 10 to 12 days after becoming adults.
The following are some management/control methods for the property owner:
• Physical/Mechanical Control: While it is not usually feasible for an individual to protect large land areas, yards and gardens can occasionally be physically protected. Where possible, home owners can erect a fence or slick barrier 18-24 inches high (chicken wire covered tightly with sheet plastic) around valuable ornamentals, flowers beds, and gardens. Mormon crickets normally cannot walk up a slick barrier placed in a vertical position. If a few Mormon crickets enter a home or building, they may be vacuumed into a disposable bag. Seal the bag and dispose of it in the trash.
• Biological Control: Natural predators include wild birds and poultry. A black wasp (Palmodes laeviventris) present in a few northern Nevada rural communities in 2006 is also reported to be the major cricket predator.
• Cultural Control: During fall clean-up, home owners should rake their lawns and turn over or till soil in their garden beds to expose the eggs. Cold temperatures will not allow egg hatching. Exposure to daily heating and freezing will dehydrate the exposed eggs, killing them.
• Chemical Control: Carbaryl (Sevin®) bait may be applied around the perimeter of properties, such as fields, gardens, and landscapes as a protection. Homeowners can usually purchase bait from private suppliers. Other pesticides including insect growth regulators are also available. Choose an insecticide or growth regulator based on the age of the cricket population, forage conditions, and whether or not the product is registered for application to the crop or site.
Mormon crickets cannibalize their dead and injured. Consequently, carbaryl bait ingested by one Mormon cricket that dies may kill a second or third with subsequent feeding among the horde. Pesticides must be applied according to the label directions to - be lawfully and effectively applied.
• Non-Chemical Bait: For those concerned with the use of traditional pesticides, there are general use products registered for application around the home: PERMA-GUARD Garden and Plant Insecticide (D-21). D-21 is a diatomaceous earth-based product that kills insects by puncturing their exoskeleton, causing them to die from dehydration. There is however, a lack of empirical data supporting its effectiveness in killing Mormon crickets, but the manufacturer claims that D-21 is just as effective as carbaryl bait and without any harmful side effects to animals, humans, or the environment.
Anyone finding Mormon crickets is encouraged to report them to the Nevada Department of Agriculture. Contact Jeff Knight, jknight@agri.state.nv.us , phone 775-688-1182 ext. 245 or a local departmental office:
