Carpenter bees!
Carpenter bees can be a real menace to one’s exterior siding – especially wood siding.
A statement from the North Carolina State Extension University regarding damage and solutions for Carpenter Bees:
“Preventing carpenter bee damage is difficult (or nearly impossible) for several reasons. Protective insecticide sprays applied to wood surfaces are effective for only a short period even when repeated every few weeks.
Although it is a time-consuming and seemingly endless task, treating the entrance holes with an insecticidal spray or dust can reduce future nesting activity. Products containing carbaryl (Sevin), cyfluthrin or resmethrin among other chemicals are suitable. Treated tunnels should be sealed with a small ball of aluminum foil and caulked after 24-36 hours. Simply plugging untreated tunnels with wire mesh or similar material might trap bees inside, but more resourceful bees will simply chew another exit hole.
Another option is to go the route of replacing wood siding with composite materials (such as masony, cement board siding, or vinyl siding) as well as replacing porch rails and balusters.” – July 1, 2018 (more…)