Nymphister kronaueri is a tiny beetle that lives among ants. They live exclusively among one species of army ant, Eciton mexicanum in Costa Rica. These army ants are nomadic, spending a few weeks in one place before migrating for about three weeks to new territory.
The beetle can move about and feed while the host colony is stationary, but when the ants move, so must the beetles. There come the mimicry. The beetle with only 1.5 millimeters length, is shaped, sized and colored just like the abdomen of a worker ant.
The beetle uses its tiny mandibles to clamp down on its host’s abdomen as the ants move. This makes it look like the ant has two abdomens. Like other myrmecophiles, or ant-lovers, these beetles likely use similar chemical signals as the host ants to avoid detection. The exact mechanism is not yet known.