The pseudoscorpion Cordylochernes scorpioides lives in decaying fig wood, the same habitat the beetle's larvae exploit. Because that habitat is patchy and short-lived, the arachnids disperse by clinging beneath the beetle's elytra, an arrangement called phoresy in which one animal is transport only.
The space is contested. Male pseudoscorpions defend territories on the beetle's abdomen, fight arriving rivals, and mate with females that board. Females may give birth during the journey, so a single beetle can arrive at a new tree carrying an entire small colony rather than a few passengers.
The beetle appears unharmed. The riders take no fluids from it and leave when it lands on suitable wood. The male harlequin's forelegs, longer than its whole body, are used to grip branches and to spar with rival males, and are not connected to the pseudoscorpion association.