Why might elytra have evolved in beetles living beneath bark?

The evolution of elytra—the hardened, thickened front wings characteristic of beetles—is believed to be closely associated with the habit of living beneath the bark of trees.1

In these confined, rugged environments, beetles require robust protection for their delicate flying wings. The elytra serve as protective covers that shield the hindwings and the abdomen from damage while the insect navigates tight spaces. This structural adaptation allows beetles to thrive in habitats where they must squeeze through narrow gaps, providing a significant evolutionary advantage for those that dwell under bark.123