Longhorn beetles spend most of their lifecycle hidden inside wood as larvae, where they tunnel and feed for extended periods—sometimes months or even years—before emerging as adults. Because of this, infestations often go unnoticed until exit holes appear or adult beetles are seen indoors.

Homeowners may notice round exit holes in wood, weakened lumber, or adult beetles appearing near windows or light sources. In many cases, the infestation began long before the wood was installed or brought inside, such as through firewood or untreated lumber.

While longhorn beetles primarily target outdoor wood and trees, using infested materials in construction can be damaging. Over time, tunneling can weaken wood and compromise its integrity. Their presence indoors is often less about an active infestation spreading and more about previously infested wood continuing to produce adult beetles. Identifying the source of the wood is key to resolving the issue.