A fascinating examination of socially parasitic invaders, from butterflies to bacteria, that survive and thrive by exploiting the communication systems of ant colonies.

Down below, on sidewalks, in fallen leaves, and across the forest floor, a covert invasion is taking place. Ant colonies, revered and studied for their complex collective behaviors, are being infiltrated by tiny organisms called myrmecophiles. Using incredibly sophisticated tactics, various species of butterflies, beetles, crickets, spiders, fungi, and bacteria insert themselves into ant colonies and decode the colonies’ communication system. Once able to “speak the language,” these outsiders can masquerade as ants. Suddenly colony members can no longer distinguish friend from foe.

Pulitzer Prize–winning author and biologist Bert Hölldobler and behavioral ecologist Christina L. Kwapich explore this remarkable phenomenon, showing how myrmecophiles manage their feat of code-breaking and go on to exploit colony resources. Some myrmecophiles slip themselves into their hosts’ food sharing system, stealing liquid nutrition normally exchanged between ant nestmates. Other intruders use specialized organs and glandular secretions to entice ants or calm their aggression. Guiding readers through key experiments and observations, Hölldobler and Kwapich reveal a universe of behavioral mechanisms by which myrmecophiles turn ants into unwilling servants.

As The Guests of Ants makes clear, symbiosis in ant societies can sometimes be mutualistic, but, in most cases, these foreign intruders exhibit amazingly diverse modes of parasitism. Like other unwelcome guests, many of these myrmecophiles both disrupt and depend on their host, making for an uneasy coexistence that nonetheless plays an important role in the balance of nature.

"[A] profoundly researched, gloriously illustrated treatise on ant symbiosis." - Nature

"A book synthesizing the biology of myrmecophiles is long overdue, and now we have it. In The Guests of Ants, Bert Hölldobler and Christina Kwapich introduce us to this amazing menagerie, synthesize centuries of observations, and bring us up to speed on the latest science…A pleasure for any curious naturalist." - American Scientist

"The Guests of Ants gives a beautifully illustrated, wide-ranging, and critical literature review of this delightful corner of myrmecology…A must for myrmecologists and entomologists, but also more generally for biologists with an interest in social insects and insect ecology." - Inquisitive Biologist

"A wonderful work that neatly weaves together the old and classic observations with recently gained insights into the fascinating but often enigmatic biology of myrmecophiles…Everyone with an interest in entomology will enjoy this book." - American Entomologist

"I urge you to immerse yourself in The Guests of Ants…What Hölldobler and Kwapich have produced is a carnival of the extraordinary; a relentless and stunningly illustrated parade of the myriad organisms that have gained footholds in virtually every aspect of ant biology…It will be the quintessential resource for generations of researchers to come." - Current Biology

"Fascinating…This encyclopedic account of the natural history of the guests of ants will surely serve as a useful and inspiring resource for myrmecologists in the years to come." - Quarterly Review of Biology

"This book is a stunning collection of these stories of myrmecophiles living with ants, with rich accounts of the interactions between guests and hosts." - Bulletin of the Entomological Society of Canada

"An essential reference for any myrmecologist or entomologist." - Canadian Field-Naturalist