“They are very destructive when there are a lot of them, but one on one, what’s not to love?” says Arianne Cease. He means grasshoppers.
Cease leads the Global Locust Initiative at Arizona State University, where he studies how locusts behave and how their destructive swarms can be controlled. While her research focuses on reducing damage to crops and communities, she also brings a deep respect for the insects themselves.
Locust swarms remain a global threat
Swarms of locusts conjure up images of ancient plagues in many people’s minds, but the danger is very real today. Around the world, swarms can destroy crops over vast regions, wipe out livelihoods, and in some areas disrupt children’s education and long-term economic prospects. A single swarm can cover hundreds of square miles—roughly the size of a large city like New York City or Phoenix.
That’s why Cease and his international research team paid close attention to finding a straightforward soil-based way to reduce locust feeding. Scientists soon realized that this approach could have life-changing consequences. To their knowledge, this is the first study to test the method in a real-world agricultural setting and show that it works outside the lab.
Testing the idea with farmers in Senegal
The researchers worked with farmers in Senegal, who regularly face outbreaks of the Senegalese locust. Unlike the desert locust, this species does not form massive swarms, but its frequent occurrences and smaller groupings can cause even more damage to local farmers. These communities have previously worked with Cease to push for a larger field study.
Each farmer planted two plots of millet – one treated with nitrogen fertilizer and one untreated.
The contrast was clear. Fertilized plots had fewer grasshoppers, less crop damage, and harvests were twice as large as untreated fields.
“This breakthrough represents an important step forward in the sustainable management of migratory pests and offers a community-based tool that expands available treatment options,” says Cease, who is also an associate professor in the ASU School of Sustainability and School of Life Sciences.
A study published in the journal Scientific reports. Associate Professor Mamour Touré of Université Gaston Berger in Saint-Louis, Senegal, served as lead author, while Cease was principal investigator of the USAID-supported project.
“The results are very important for the scientific community and also for Senegalese farmers,” says Touré. “The study gave them a better understanding of locusts and locusts, as well as a practical way to control them at a local level.”
Why soil quality shapes grasshopper behavior
The Global Locust Initiative is part of the Julie Ann Wrigley Global Futures Laboratory and focuses on the many systems that affect locusts. Environmental conditions, insect biology and behavior, economic pressures, public policy, and land management all contribute to cycles of destruction—as well as create opportunities to break them.
After more than 15 years of research, Cease has discovered a consistent pattern. Crops grown in nutrient-poor soil tend to favor grasshoppers because these plants contain high levels of carbohydrates and very little protein.
“This carbohydrate bias or ‘doughnut diet’ is optimal for grasshopper and swarming grasshopper populations,” Cease says. Like endurance athletes who rely on carbohydrates for energy, grasshoppers depend on high-carbohydrate plants to power their long-distance movement.
Plants grown in nitrogen-rich soil tell a different story. They contain more protein and less carbohydrates, making them a difficult food for locusts. Their bodies are struggling to process excess protein and are not getting enough energy to thrive.
Protein-packed plants keep pests at bay
These findings led to a key question. Could shifting the balance of protein and carbohydrates in crops prevent grasshopper damage? Earlier laboratory experiments and field observations suggested that this would be the case, but the idea had never been tested on working farms. For Cease, this gap was the next obvious step.
Two Senegalese villages that had previously worked with her volunteered to participate. Their farms regularly suffer heavy losses from swarms of Senegalese locusts.
In the experiment, 100 farmers each cultivated two millet plots – one treated with nitrogen fertilizer and one left untreated for comparison.
The researchers weren’t sure whether locusts could still enter the treated plots from nearby untreated fields, or whether the higher-protein plants might attract other pests. To find out, the team counted locusts three times during the growing season and measured crop damage and recorded yields at harvest.
Results were decisive. Treated plots had fewer grasshoppers, less leaf damage and twice the yield of millet at harvest. The team also found no evidence that adding nitrogen made other pest problems worse.
From fertilizer to compost solutions
Although nitrogen fertilizer was supplied for the study, it is not a realistic long-term option for many farming communities. Sustainable control requires affordable methods that also protect soil health.
“The ongoing work focuses exclusively on compost, and we seem to be getting the same results,” says Cease.
USAID funding for the project ended in early 2025, but farmers in Senegal continued composting themselves, encouraged by the results.
“Farmers unanimously declared that they no longer burn crop residues after clearing the land, but instead practice composting to fertilize their fields and thus help reduce locust infestation. This technique has been fully mastered by the project,” says Touré.
The research team is now looking for additional funding to expand the work to other regions heavily affected by locusts.
Why Locust Research Matters in the United States
The US currently has no native locust species. So why study them at all? Cease says that could change. He keeps a close eye on the locusts of Central America, whose range extends to within about 200 miles of the US border.
“We can say with fairly high confidence that Texas will be very suitable for locusts in about 10 to 15 years,” Cease says. “Whether or not it will cause a problem remains to be determined, but it’s definitely something we should be aware of.”
Even without locusts, locusts are already a major problem across the country. There are 12 key species known collectively as the Dirty Dozen.
According to the USDA, these 12 locusts (plus one cricket) are among the most serious pest threats in the western United States. When they swarm, they can remove pasture and outcompete livestock for food, causing serious problems for farmers.
While chemical pesticides remain the primary control tool, the Global Locust Initiative is working to identify alternatives that are safer for people and the environment.
What scientists have learned from locust outbreaks abroad may prove crucial at home, helping the U.S. more effectively manage migratory pests and prepare for the possibility that locusts may one day cross the border.
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