“An Army of Frogs” is one of several collective nouns used for a group of frogs, and it’s easy to see why it stuck. Picture dozens, sometimes hundreds, of frogs surging toward a pond after a heavy rain, all moving with the same single-minded urgency. That’s about as close to a marching army as the animal kingdom gets.
Unlike some of the older, more thoroughly documented collective nouns for birds and game animals, the exact origin of “army” for frogs isn’t well recorded. Many amphibian group terms are believed to be newer additions to the language, chosen more for how well they fit the animal’s behavior than for any centuries-old hunting tradition.
And the behavior fits. Frogs are famous for explosive breeding events, where large numbers converge on a single body of water within just a few nights, drawn by rainfall, temperature, and the calls of males already there. The result is loud, crowded, and about as far from stealthy as an amphibian gets — less an ambush, more an invasion.
Frogs in this kind of gathering are also there for safety in numbers. A pond full of calling males makes it harder for any single frog to be picked out by a predator, and the sheer volume of eggs laid during these events helps offset the fact that most tadpoles never make it to adulthood.
So next time you hear that unmistakable evening chorus rising from a wetland, you’re not just listening to frogs. You’re listening to an army mustering.
Example: “After the spring storm, an army of frogs converged on the retention pond behind the school.”
Related: Collective Nouns for Amphibians · What Is a Group of Frogs Called?