With their tonsured heads, white faces, and striking cowls, the monkeys might vaguely resemble the Capuchin monks for whom they were named. How they act is something else entirely. They climb onto each other’s shoulders four deep to frighten enemies. They test friendship by sticking their fingers up one another’s noses. They often nurse—but sometimes kill—each other’s offspring. They use sex as a means of communicating. And they negotiate a remarkably intricate network of alliances, simian politics, and social intrigue. Not monkish, perhaps, but as we see in this downright ethnographic account of the capuchins of Lomas Barbudal, their world is as complex, ritualistic, and structured as any society.

Manipulative Monkeys takes us into a Costa Rican forest teeming with simian drama, where since 1990 primatologists Susan Perry and Joseph H. Manson have followed the lives of four generations of capuchins. What the authors describe is behavior as entertaining—and occasionally as alarming—as it is recognizable: the competition and cooperation, the jockeying for position and status, the peaceful years under an alpha male devolving into bloody chaos, and the complex traditions passed from one generation to the next. Interspersed with their observations of the monkeys’ lives are the authors’ colorful tales of the challenges of tropical fieldwork—a mixture so rich that by the book’s end we know what it is to be a wild capuchin monkey or a field primatologist. And we are left with a clear sense of the importance of these endangered monkeys for understanding human behavioral evolution.

Insects that are the least bit social may gather in modest groups, like the dozen or so sawfly larvae feeding on a pine needle, or they may form huge masses, like a swarm of migratory locusts in Africa or a cloud of mayflies at the edge of a midwestern lake or river. Why these insects get together and what they get out of their associations are questions finely and fully considered in this learned and entertaining look at the group behavior and social lives of a wide array of bugs.

The groups that Gilbert Waldbauer discusses here are not as complex or tightly organized as the better-known societies of termites, wasps, ants, and bees. Some, like the mayflies, come together merely because they emerge from the water in the same place at the same time. But others, like swarms of locusts, are loosely organized, the individual insects congregating to migrate together for distances of hundreds of miles. And yet others form a simple cooperative society, such as the colony of tent caterpillars that weaves a silken tent to house the whole group.

Waldbauer tells us how individuals in these and other insect aggregations communicate (or don't), how they coordinate their efforts, how some congregate the better to mate, how some groups improve the temperature and humidity of their microenvironment, and how others safeguard themselves (or the future of their kind) by amassing in such vast numbers as to confound predators.

As engaging and authoritative as Waldbauer's previous books, Millions of Monarchs, Bunches of Beetles will enlighten and delight those who know their insects well and those who wish to know them better.