Weed & Pest
Early identification of grasshoppers, Mormon crickets leads to more effective controlWritten by Heather Smith Thomas
Nearly 400 species of grasshoppers are native to the 17 western states. Mormon crickets are closely related insects that are also highly mobile and capable of migrating long distances. In large numbers, they may devour nearly all forage plants in their path.
Bruce Shambaugh is the grasshopper/Mormon cricket national operations manager and state plant health director for Wyoming for the USDA Animal and Plant Health Inspection Service (APHIS) Plant Protection and Quarantine unit (PPQ). He oversees all of the PPQ programs, including grasshoppers, in the state of Wyoming and also manages field operations for the entire grasshopper/Mormon cricket program in the 17 western states.
“There are differences from state to state because of differences in the land where these insects occur, and the people involved in these programs. Each state has evolved their own type of programs, and I try to make these as consistent as possible and still allow flexibility for what they need to do, based on how it has worked for them in their states,” he says.
Even though there may be dozens of species of grasshoppers in any given rangeland ecosystem, only a few are considered pests.
Most years, they cause very few problems because there is enough forage for them and for the livestock and wildlife that also use the pastures.
However, these insect populations sometimes reach outbreak levels.
If it’s a dry year and forage is already short, grasshoppers or crickets cause significant damage and economic loss. In these situations, the land management agencies – both federal and state, county and local governments, private groups and/or individual landowners can request assistance from USDA’s Animal and Plant Health Inspection Service (APHIS) to suppress the insect populations.
“Our program goal includes not only suppression treatments but also population surveys so we know where these insects are. We do a nymph survey early in the year, to get field data on numbers of young grasshoppers, to enable us to make management decisions. We also conduct an adult survey later on in the summer and early fall,” says Shambaugh.
“This information goes onto a map to give our best attempt at predicting where to start looking the following spring. We provide this information to all the cooperators, stakeholders, land managers, Game and Fish, landowners, etc., so we can all work together to manage the program for both grasshoppers and Mormon crickets. We try to involve everyone, including private landowners. We all have a common goal to maintain a healthy rangeland ecosystem,” he explains.
Shambaugh notes that not all grasshoppers are detrimental to rangelands.
“Only a handful of grasshopper species are heavy grass-eaters that can occur in densities that could cause significant damage. When we go out on the land to do early spring surveys, our areas of focus are based on what our adult surveys showed us the previous fall. Any information we received through landowner meetings or meetings with cooperators during the year – and reports they’ve given us – is helpful,” he says.
“In the adult survey, we heavily rely on landowners who are out running cattle, doing their ranch work. They can call directly to us or to a county weed and pest district, Extension service or maybe a local land manager who can relay information to us. Perhaps they were out fixing fence or trailing cows and noticed a lot of grasshoppers in certain areas,” says Shambaugh.
Shaumbaugh explains that early in the year, grasshoppers can be difficult to spot because the young bugs are less than one-quarter of an inch long.
“This is one of the challenges, to get landowners looking for these young insects early in the spring, at that small size,” he says. “A person often has to get out and walk or get down on hands and knees to look closely at the grass. This is normally not what a rancher is doing. He’s usually in a vehicle or on a 4-wheeler or a horse concentrating on other things.”
Shaumbaugh adds, “It’s a challenge, but the more we know what to look for, it can help to notice whether there are one or two of them hopping or 10 or 20.”
“If the rancher contactsthe State Plant Health Director (USDA-APHIS), then we can come out and do a survey. We respect private land and don’t go across it unless we have permission,” he says.
Addressing the populations
When it looks like there might be an impending grasshopper explosion with a lot of young insects in the spring, timeliness is crucial for suppression efforts.
“This is the largest challenge – to identify a high population quick enough to have time to make any management decisions or suppression treatments, if that’s the first year we know of it,” says Shambaugh.
“Adult surveys in late summer are important to help us identify what might be – or what might lead to – potential problems in the next year or two. If we can do some planning and get interested landowners coming to meetings over the winter, we can do an effective job on suppression treatments the next spring. It is very difficult to do any sort of suppression treatment if that population is just noticed that year,” he explains.
The preferred chemical for treatment is an insect growth regulator, so timing is very important.
“It doesn’t have any effect on adult grasshoppers or crickets. The timing window for this treatment is much shorter than for insecticide options. The growth regulator is by far the preferred choice because it is more environmentally friendly and doesn’t adversely affect as many non-targeted species,” he explains.
“In the old days, we wanted to get rid of them all, but that’s not our goal today. These insects are part of the ecosystem and do a lot of good, providing food for other animals and birds,” Shambaugh says.
Suppression is a better goal, keeping numbers to a reasonable level. The earlier a treatment is deployed, the better effect it will have.
On a bad year, with an explosive population of grasshoppers or crickets, knocking them back a bit with this kind of treatment can ensure that they won’t compete so much with the livestock and wildlife that might otherwise be short of feed.
“We should keep our eyes open for young hoppers and then report to our local State Plant Health Director, State Ag Department or local cooperative Extension agent,” he adds.