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.
Ravens prove problematic in Wyoming, some control mechanisms availableWritten by Saige Albert
A 2011 study initiated by the Meeteetse Conservation District and USDA Wildlife Services aimed to examine the effect of predators on sage grouse populations within the Bighorn Basin.
“Everyone points the finger at grazing or oil and gas when we look at sage grouse impacts,” says Meeteetse Conservation District Resource Specialist Steffen Cornell. “We know that predation also has an impact.”
By partnering with a variety of groups, including conservation districts, industry people, county predator boards and others, Cornell noted they received ample financial and moral support from the region.
“We contracted with one researcher from the National Wildlife Research Center for the first two years and another for the remaining three years,” Cornell adds. “We’ve just ended the first five years of the study.”
Before concluding the study, the National Wildlife Research Center produced a preliminary report to the Wyoming Natural Resource Trust.
“The preliminary report indicated if we don’t do something about ravens on one of our study sites, the local sage grouse population faces possible eradication in spite of the fact that it has some of the best sage grouse habitat in the Bighorn Basin,” Cornell says.
The National Wildlife Research Center is now finalizing their study results for publishing in a peer-reviewed scientific journal.
Now that their contract with the National Wildlife Research Center has concluded, Cornell explains that they have decided to move forward with additional research.
“We decided we wanted to move on and focus more on ravens,” he continues.
Cornell explains that Meeteetse Conservation District, with continued field assistance from Wildlife Services, is moving forward with new research to determine if the impact of ravens can be alleviated.
“Ravens are tremendously successful at whatever they do, and one of those things is seeking sage grouse and depredating nests,” he says. “Since the inception of this project, we’ve secured funding through the Animal Damage Management Board and the Sage Grouse Local Working Group, and we are going to continue to approach those groups as well as others.”
As they continue to seek funding to continue the project, Cornell adds that they are approaching their first field season to look at reducing raven predation.
“We just got a scientific collecting permit on March 9 from Fish and Wildlife Service,” he says. “We will be capturing and radio marking 12 ravens in two locations in Park County.”
Six ravens will be trapped at each study side, along with 10 sage grouse.
“We will split each site into a treatment and control area,” Cornell continues. “On the treatment site, we will be actively locating and removing raven nests. Our permit allows us a quota on the number of eggs and chicks that we can remove.”
While their scientific collecting permit allows the removal of eggs and chicks, Cornell adds that their goal is to remove the nests prior to egg laying to avoid killing chicks, if possible.
Nest removal will occur primarily during the nesting season for sage grouse.
“Nesting pairs of ravens are very territorial,” Cornell explains. “Some research suggests that those nesting pairs are also the specialists when it comes to depredating sage grouse nests.”
“The logic behind our study is that if we can preoccupy the ravens enough that they are constantly trying to rebuild their nests, it would prevent them from having the time to go out and forage for sage grouse eggs,” he says. “We think they will be more worried about producing their own clutches than seeking sage grouse eggs.”
“We are hoping this study sheds some light on other management approaches that are non-lethal and maybe more socially acceptable,” Cornell adds, mentioning that they hope to continue to gather data into 2017.
Hayden Wing and Associates of Laramie, one of the foremost raven and sage grouse experts in the state, has been contracted to assist in the project.
“During our study, coyotes were the number one predators on sage grouse nests,” Cornell says, adding that coyotes more easily managed because of the lack of protection for the species. “We can manage coyotes, and that is being done today. Ravens are protected under the Migratory Bird Treaty Act. It’s much harder to knock their numbers down for the purpose of benefitting sage grouse, but we’re hoping that we see a rise in sage grouse nest success from raven nest removal.”
Throughout the state of Wyoming, USDA Wildlife Services State Director Mike Foster says that raven control work is being conducted for health and human safety reasons and to protect livestock.
“We do raven work to protect calves and lambs when they are born,” he says. “This happens all throughout the state when it's necessary.”
Raven control is conducted through the use of an avicide called DRC 1339. The avicide is only available to Wildlife Services.
“This avicide is a very effective product,” Foster says. “We use it on various baits including dog or cat food, which is allowed under a special use permit from the Environmental Protection Agency (EPA).”
When initiating a control activity, Foster explains that Wildlife Services begins by pre-baiting the area of concern. Once the ravens are taking the bait well, the avicide is introduced.
“The avicide affects the kidneys and heart, and the birds experience a quiet and apparently painless death one to three days following ingestion,” he says. “They usually die on their roosts, and there is no risk of secondary toxicity.”
DRC 1339 is generally unstable in the environment and is rapidly metabolized in the target species. Scavengers consuming the dead individuals are not affected.
“There has never been a known case of secondary poisoning,” says Foster.
“Ravens are protected under the Migratory Bird Treaty Act,” Foster mentions. “Wildlife Services has the permits to allow us to do this work. Private individuals can also get the permits, but DRC 1339 is only available to Wildlife Services.”
Air turbulence plays a role in pesticide dispersion when spraying fieldsWritten by Natasha Wheeler
“Usually, farmers will get up early in the morning to go out and spray their fields as soon as they can see enough. But, what we really ought to do is wait until about two hours after sunrise,” remarks Tom Wolf of Agrimetrix Research and Training.
Wolf recommends spraying after the air temperature has risen two degrees Celsius above the temperature at sunrise, the coldest time of the night.
“By then, the sun has warmed up the soil, the air has warmed up a little bit, and we start to get a little bit of breeze so there is more turbulent mixing,” he explains.
Many producers want to spray in calm conditions to avoid off-target movement, but calm conditions can also be associated with inversions, which are unfavorable for spraying.
“An inversion is defined by a temperature difference between two heights,” he explains, describing how there can be different temperature layers in the air.
In sunny conditions, the sun heats up the soil, and the ground becomes warmer than the air above it.
“The higher up we go from the ground, the more the air cools. That’s a normal daytime condition – air near the ground is warmer than the air above it,” Wolf says.
Even without the presence of the sun, air is typically cooler higher up, as illustrated by snowy mountaintops.
“There is less air pressure there. The rate of cooling with elevation is related to air pressure, and it’s called the adiabatic lapse rate. It means, if we take a parcel or air and simply elevate it, it will expand a little bit because there is less air pressure the higher we go,” he comments.
“That expansion takes work. The molecules have to physically move further apart and that work is temperature related,” he adds.
Typically, the rate of cooling is approximately one degree Celsius per 100 meters.
“When it’s sunny out, that rate of cooling is actually much faster because the soil has warmed the air near the ground, and as that dissipates, it causes the air to cool faster,” Wolf describes.
A parcel of air that is elevated from the ground on a sunny day, despite cooling as it rises, will still be warmer than the air around it, and therefore, it will continue to rise.
“Once that parcel of air rises, it’s gone,” he states. “Likewise, if we displace a parcel of air from above and move it down, the opposite happens.”
A cold parcel of air that sinks is still colder than the air around it when it nears the warm soil, so it is pushed all the way to the ground.
“What we have is very high turbulence – lots of parcels rising and falling. That’s called turbulent conditions, and it leads to dispersion of spray,” he explains.
A spray cloud released into turbulent air moves across the currents and disperses out over the field until it’s gone.
“If I was to release a spray cloud a few meters to my right, by the time it was a few meters to my left, it would probably be about five meters high. It would just go up, and by the time it reaches a little bit further downwind, there’s almost nothing left of it. It’s gone into the atmosphere. That’s why spraying under sunny daytime conditions is favored,” Wolf says.
On a day without sun, the ground can be much cooler than the air above it.
“If we take that same parcel of air and make it rise, it will warm a little bit as it rises, but it will still be colder than the air around it. As a result of that, it will fall back down to the ground and fall to exactly the same place where it came from,” he continues.
A parcel of air from above that is displaced downward will likewise return to where it started. Therefore, no mixing takes place in the air, creating two distinct layers.
“The parcels of air cannot be displaced,” states Wolf. “We see this in the evening fog sometimes, for example when the fog is hanging just at windshield height,” describes Wolf.
These distinct temperature layers are known as an inversion, and inversions are most common early in the morning and throughout the night.
“The reason it’s dangerous to spray in an inversion is because if the spray cloud doesn’t mix up, it will stay very concentrated, and it will cause a great deal of damage where it sits,” he remarks.
Large spray particles fall to the ground, but smaller particles remain buoyant in the air and can be carried for miles without dispersing.
“The small particles rely on atmospheric turbulence to disperse themselves. That’s what the sun will do for us,” he notes.
Before spraying, Wolf recommends, “We should take the temperature at sunrise and wait until we get about one or two degrees Celsius above that. Then, we’ll know the sun has done its work.”
Pesticide application procedures affected by protection standardsWritten by Natasha Wheeler
On Sept. 28, the Environmental Protection Agency (EPA) finalized revisions to the worker protection standard, which applies to pesticide handlers and people who perform hand-labor tasks in pesticide-treated crops.
Revisions affect pesticide regulations concerning training, safety and hazard communication, personal protective equipment (PPE) and supplies for washing and emergency decontamination.
“There is a table that the EPA put out called ‘Comparison of the New Protections to the Existing Protections,’ and it is five pages long,” comments Wyoming Ag Business Association Executive Director Keith Kennedy.
One of the major changes to the worker protection standard is what defines employing someone.
“EPA defined ‘employ’ as anyone self-employed, contracted or contracted through a third party. Operations will have to make certain that these employees all have training, access to records, etc.,” Kennedy says.
This includes family members who work for operations that run under corporation or LLC titles and therefore do not qualify for family exemptions.
“There are some operations that are partnerships where this won’t be an issue, but we see a lot of folks than have an LLC to operate their farm or ranch,” he notes.
Although, the new definition of immediate family is now more inclusive than it was in the old standards.
“The definition of immediate family has been extended to include in-laws, grandparents, grandchildren, aunts, uncles, nieces, nephews and first cousins,” Kennedy explains.
Other important changes in the EPA standards pertain to training regulations for workers that may come into contact with pesticide application areas.
“The certification and training proposed rule is out for comment right now,” Kennedy notes. “It used to be that employers only had to train workers and handlers every five years, but now that has to be done annually.”
The five-day grace period with abbreviated training has also been eliminated, and workers must be trained before they work in an area where a pesticide has been used or a restricted-entry interval has been in effect in the past 30 days.
“Let’s say I have someone come out from the implement dealer to work on some of my equipment that happens to be in an area that was treated – I will have to train them first,” Kennedy remarks.
He continues, “It’s probably something that is going to affect people more than it appears at first glance.”
New topics have also been added to the previously required basic training items, including 11 topics for workers and 13 topics for handlers. New content will be required in all trainings by November 2017.
“There are now 23 topics for workers and 36 topics for handlers,” Kennedy says.
Record keeping requirements have also increased with the new EPA worker protection standards, for both training and hazard communication.
“Employers now have to keep training records for two years and have copies available for employees if they request them,” Kennedy says.
Previously, employers could have a voluntary certification card system, but they were not required to maintain records for their employees.
“We have to keep our application records and safety data sheets for two years after application as well. Probably one of the biggest changes is that we have to post a warning in the area where we have treated if the restricted-entry interval is more than 48 hours,” he adds.
New requirements also include the addition of a minimum age requirement and the suspension of pesticide application if other people are present in the application exclusion zone, an area up to 100 feet surrounding the application equipment.
“There is a minimum age of 18 for all handlers and anybody who will be in the area before the end of the restricted-entry interval,” Kennedy notes.
He also explains, “Applicators will have to shut down if they see people in the area that they are treating.”
Workers handling pesticides will be required to have the appropriate PPE, which includes meeting Occupational Safety and Health Administration (OSHA) standards and keeping records of employee PPE training.
“At the mixing or loading site, six gallons of water that can flow for 15 minutes must be available for each handler or applicator who is there. In other words, there has to be water on-site that is capable of flowing at 0.4 gallons per minute for 15 minutes,” Kennedy explains.
This requirement pertains to eye wash systems for workers using products that require eye protection or use of pressurized closed systems. For these situations, workers are also required to have a pint of water with them at all times. One gallon of water for each worker and three gallons of water for each handler must be available for routine washing.
“The new rule goes into effect 60 days after publication. That is sometime in November,” Kennedy mentions. “Most of the provisions will apply one year from the publication date, so there are two seasons for training to get folks up to speed.”
There are also a number of provisions that will take affect in November 2017.
UW entomologist encourages early management of grasshopper populationsWritten by Natasha Wheeler
Worland – “I think grasshoppers are one of the most important and most frequent pests on small acreages for range and forage production,” remarked University of Wyoming (UW) Assistant Extension Entomologist Scott Schell at WESTI Ag Days in Worland on Feb. 20.
There are approximately 120 species of grasshoppers in Wyoming, and there are enough differences between them that it is important to identify species that may be found in certain regions.
“In Wyoming, we have about a dozen species that are serious pests. Some of those are only pests in rangeland, others are a multi-threat, and some of them are more of a threat in croplands or gardens and horticulture with ornamental plants,” Schell explained.
As an individual insect, a grasshopper generally has very little impact, but high numbers can cause significant damage. An adult two-striped grasshopper, for example, can waste six times as much forage as it eats, and it can eat its weight daily in green vegetation.
“If there are 30 two-striped grasshoppers per square yard, which is not necessarily a very heavy infestation, that’s 200 pounds of grasshoppers per acre,” he stated. “That’s like having sheep on every acre of our field, eating their weight daily and wasting six times more than they eat.”
Although the two-striped grasshopper is one of the more destructive species, other species can also make an important impact on an operation.
Some grasshopper species overwinter as nymphs, but a majority of species spend the winter as eggs, buried within the top 1.5 inches of soil. Typically, the eggs hatch in the spring, coinciding with the emergence of new green vegetation so they have plenty of food to eat.
“They start out looking like miniature adults, and after growing stages, they have to molt because they have a hard exoskeleton. Most of them have about four or five molts before becoming adults,” he explained.
In most species, full-sized adults grow wings and then begin to lay eggs in the soil.
“Usually, it’s not recommended to treat at that point. If we do treatments, we want to try to do it early to prevent damage, growth and any egg laying for the next year,” he said.
Grasshoppers are generally most vulnerable during their first stage of life after hatching, and bad weather or other events can significantly impact their populations during that time.
“That’s probably the reason we have some years that are good and bad with grasshoppers,” he noted.
Some species of grasshopper are capable of traveling great distances. The insects have been observed marching seven miles to find food, and airplanes have encountered them at 8,000 to 10,000 feet of elevation.
In the 1930s, grasshoppers were documented flying up to 180 miles from South Dakota to Wyoming.
However, Schell noted, “Most years, grasshoppers die where they hatch.”
Large seasonal populations are more likely due to mortality rates than migration. Experts estimate that in any given year, there are enough eggs deposited in the soil to support an outbreak the following spring.
“For example, for one species found in the Bighorn Basin, 40 grasshoppers can produce up to 900 eggs per square yard,” he comments, adding that the insects prefer to deposit their eggs along irrigation ditches where the ground has not been cultivated or sub-irrigated.
“If we have grasshoppers originating in crop areas, a lot of times they’ll be in the corners, along the roadsides, fence rows, and all of those places that are not sub-irrigated where the grasshoppers have had successful development in the soil and hatched,” he described.
This can mean grasshoppers are sometimes more prevalent in no-till or minimum till systems, where equipment has not disrupted the soil and damaged the eggs.
“Protecting the field from the grasshoppers before we get into a field is the most important thing because it’s so much cheaper and easier to treat an infestation when they’re out of the field,” he continued.
Treatment options labeled for crop use are typically much more expensive than non-crop treatments, and Schell suggested preventing incidents that require the use of chemicals if possible.
Different species of grasshoppers can also hatch over a period of 52 days, so multiple treatments may sometimes be necessary.
“Because grasshoppers have prolonged hatching periods, we may need to spray again. Scout the area to see if a hatch is going on, and if a landowner needs to, they should spray again. The products can start to wear off after a few weeks,” he remarked.
New vegetation will also be untreated and preferable to the insects.
“Applying early is critical,” he stated.
Schell also reminded producers to read all product labels, follow directions closely and to wear appropriate protective equipment when applying pesticides.
“We want to determine how bad the infestation is, what stage the grasshoppers are in, what species they are and what threat they may pose to our broadleaf crops or forages,” he said.