[4] Multiple other species, such as P. latipennis, that were initially identified by a few specimens were later made synonymous with Phloeodes diabolicus starting in 1936 and continuing until 2006.

[6] These beetles are believed to be non-specific decomposers eating rotten wood from many trees and shrubs and the fungi that grow upon them, however, Phloeodes diabolicus is noted to be found most frequently underneath the bark of decomposing oak trees and believed to prefer white rot fungi as a food source.

This species is flightless with a fused shell theorized to have evolved for protection from crushing and evaporative moisture loss over its long lifespan of approximately eight years.

[7] Other commonalities with the rest of its associated family include a tendency to play dead when threatened and the ability to go long periods without food or water.

[1] The flattened shape and low-to-the-ground profile of the diabolical ironclad beetle, in addition to its tough exoskeleton, makes it extremely hard to crush.

The back of the beetle is not interlocked in the same way, allowing the bottom halves to slide past each other, providing flexibility to absorb squishing compression.

Protrusions called blades fit together like jigsaw pieces, glued together by proteins aiding in damage resistance.