“Saying ‘Oh, there’s locusts in northern Kenya’ doesn’t help at all,” Mr. Cressman said. “We need longitude and latitude coordinates in real time.”

Rather than try to rewrite the locust-tracking software for newer tablets, Mr. Cressman thought it would be more efficient to create a simple smartphone app that would allow anyone to collect data like an expert. He reached out to Dr. Hughes, who had already created a similar mobile tool with the Food and Agriculture Organization to track a devastating crop pest, the fall armyworm, through PlantVillage, which he founded.

PlantVillage’s app uses artificial intelligence and machine learning to help farmers in 60 countries, primarily in Africa, diagnose problems in their fields. Borrowing from this blueprint, Dr. Hughes and his colleagues completed the new app, eLocust3m, in just a month.

Unlike the previous tablet-based program, anyone with a smartphone can use eLocust3m. The app presents photos of locusts at different stages of their life cycles, which helps users diagnose what they see in the field. GPS coordinates are automatically recorded and algorithms double check photos submitted with each entry. Garmin International also helped with another program that worked on satellite-transmitting devices.

“The app is really easy to use,” said Ms. Jeptoo of PlantVillage. Last year, she recruited and trained locust trackers in four hard-hit Kenyan regions. “We had scouts who were 40- to 50-year-old elders, and even they were able to use it.”

In the last year, more than 240,000 locust records have poured in from East Africa, collected by PlantVillage scouts, government-trained personnel and citizens. But that was only the first step. Countries next needed to act on the data in a systematic way to quash locusts. In the first few months, however, officials were strategizing “on the back of envelopes,” Mr. Cressman said, and the entire region had just four planes for spraying pesticides.

When Batian Craig, director of 51 Degrees, a security and logistics company focused on protecting wildlife, saw Mr. Cressman quoted in a news story about locusts, he realized he could help.