Drywall or plasterboard consists of wood, paper and gypsum plaster. Any insect that eats wood will eat drywall. Some wood-eating insects like termites damage drywall by boring tunnels through the structure, causing it to weaken. But some wood-eating insects cause very little damage to homes, according to University of Minnesota entomologists John F. Kyhl and Jeffrey Hahn.
There are three major types of termites: dampwood termites, drywood termites and subterranean termites. All live in vast colonies, which makes their destruction of any wooden structure thorough. Thousands of termites tunnelling into wood do far more damage than just a few solitary wood-eating insects. Termites exploit any cracks or openings in drywall to gain easier access into the structure. Termite damage appears as small holes on the drywall surface with little piles of sawdust on the floor underneath the holes. The sawdust is frass or termite droppings.
Larvae of powderpost beetles eat wood and drywall, but the adults do not. These beetle larvae damage wood or sheetrock much more slowly than termites. Female beetles lay their eggs directly on wood so the newly-hatched larvae can tunnel directly inside. Wood offers both food and shelter from predators. If infested wood from lumber or trees is used to make drywall, larvae can survive to tunnel through the drywall. Other places where larvae can hollow out tunnels include wooden toys, wooden tools, bamboo objects and books. Powderpost beetle damage appears similar to termite damage.
Carpenter ants tunnel into drywall to make homes for their colonies. They cause damage similar to termite damage, but the ants don't actually eat wood or drywall. These large black ants eat whatever food they can find near their tunnels and cannibalise dead carpenter ants. Infested drywall may need removing before a home can be treated, advises North Carolina State University entomologist Michael Waldvogel.
Powderpost beetles can be easily treated with over-the-counter spray insecticides in any area of the drywall that shows entry holes or other signs of damage. But treating for carpenter ants and termites is far more difficult. They live in colonies. Unless the queen of the colony is killed, she will merely keep laying eggs to replace any workers killed. Damaged drywall may need replacement. Only a professional exterminator should treat a home for termites. It is possible to treat carpenter ants through sprays and food baits without an exterminator, but difficult.
- University of Minnesota Extension: Nusiance Wood Borers and Seed Insects in Homes; John F. Kyhl and Jeffrey Hahn; February 2000
- University of Kentucky College of Agriculture; Termite Control: Answers for Homeowners; Mike Potter; March 2004
- "Green Building & Remodeling For Dummies"; Eric Corey Freed
- University of Nebraska-Lincoln: Powderpost Beetles; Dennis M. Ferraro
- "Real Estate Home Inspection: Mastering the Profession"; Russell W. Burgess; 2003