Fifty years ago, an entomologist named Thomas J. Walker at the University of Florida, Gainesville saw his cats chasing bugs. Which most anyone who takes their cat outside, or who’s watched their cat when a bug gets inside, can relate to — but with one key difference.
Whereas we would say, “my cat chases bugs,” Walker said: “I have observed two domestic cats apparently locating singing insects by their sound.” He was a scientist, after all, and keenly observant. “One cat was observed to run toward a coneheaded grasshopper (Neoconocephalus triops) when it began to sing and to capture it.”
Those words come from “Experimental Demonstration of a Cat Locating Orthopteran Prey by the Prey’s Calling Song,” published in 1964 in the journal The Florida Entomologist and describing the bug-hunting proclivities of Walker’s cats at length. It’s an interesting paper in several respects, foremost the context. “There has been,” wrote Walker, “no previous experimental demonstration that a predator uses the acoustic signals of its insect prey in capturing it, but circumstantial evidence for such behavior has been advanced several times.”
To paraphrase, Walker didn’t know if predators locate prey by listening to their calls — something that seems painfully obvious. Any number of naturalists or hunters would have answered that question decisively. Yet to Walker, their testimony was “circumstantial,” lacking the certainty provided by experimental rigor. Something might be self-evident, even glaringly so, but still it required testing. This is why we we love science, and also why science wants to make us bang our heads on a desk.
And so Walker, being a good and careful scientist, designed an experiment in which he hung a speaker (endearingly specified as a University Sphericon Super Tweeter Model T-202) above the ground on a tree trunk. His cat ignored the silent speaker — but when he played a recording of a katydid, the cat searched in vain for the bug. Voila! Experimental evidence.
Beyond that little lesson in methodical empiricism, Walker’s paper is also one of the earliest mentions I could find in the scientific literature of cats eating bugs, and in particular eating crickets, the insect on which we expect to base our own recipe. (Though, to be sure, there are likely many possible insects out there. That the industry has focused on a few species is an interesting story for another post.)
It’s not the only such paper. We’ve all seen our cats eat bugs, and there’s a great deal of research describing this, much of it coming from studies of free-ranging feral cats conducted by researchers concerned about their predation on native species, particularly on islands where fauna evolved without cats around.* Aside from predation issues, these findings — reviewed by Esther Plantinga, Guido Bosch and Wouter Hendriks in the British Journal of Nutrition, and also see this, this, this, this and this — have implications for our understanding of domestic cat nutrition.
Among them: cats eat insects regularly. Invertebrates show up routinely in feral cat diets. The total amount of insects they consume is relatively small — mammals are their most common prey, usually followed by birds — but consume they do. Depending on circumstance, such as an especially rich hatch or the limited availability of other food, the proportion of insects in their diets increases markedly. Indeed, a study of domestic cats in the city of Auckland, New Zealand found that bugs — mostly crickets and cicadas — were actually their most common prey in a highly urbanized area.
All this doesn’t guarantee that an insect-based diet will work. Someone might say, rightly, that cats don’t eat insects in great quanity. Yet they eat more bugs than they do fish, there’s enough research to say — not on our own, but in consultation with researchers, and in reference to analyses of cricket nutrient composition — that cats certainly might be able to thrive on an insect-based diet.
Much testing will be needed. First we’ll need to determine the digestibility of such a food, starting with laboratory-based digestion-in-a-dish methods, and then moving on to ethical, fully transparent testing on cats. We’ll need to be certain there’s no unusual allergic reactions to insect material. And of course we’ll need to make sure that cats like their bug-based food. If nature is anything to go by, they’ll love it.