In small specimens the pubescent spots on the elytra disappear almost completely and the legs and antennae turn to a reddish color.

Larvae usually pupate just beneath the wood surface and eclose in mid to late summer.

Once the exoskeleton of the newly emerged adult beetle has hardened sufficiently the adults cut oval exit holes 6–10 mm (¼ to 3/8 in) in diameter, typically leaving coarse, powdery frass in the vicinity of the hole.

[8] Hylotrupes bajulus preferentially attacks freshly produced sapwood of softwood timber.

Contrary to the name "old-house borer", the species is more often found in new houses; maybe because the beetles are attracted to the higher resin content of wood harvested more recently than 10 years earlier.