I have done a number of posts here about the pest known as anobiid beetle which is so common in crawl spaces here in the Pacific Northwest. The insect leaves exit holes in soft lumber and will live for years and years if the conditions are right -- literally destroying the substructure of a home. As a home inspector I know lots more about locating the pest and its biology than how to go about actually slathering chemicals on it, as that must be done by a licensed pest control operator. A week back, while I was teaching at Bellingham Technical College, Dr Dan Suomi of the WSDA offered to come in and speak to the class. He is an entomologist, the main state enforcement officer we home inspectors might see, and did graduate level research a few years back on a common chemical control used today, sodium borate. You might have heard of it. It is low toxicity and actually similar to 20 Mule Team Borax, the hand soap that was around even when I was a kid and was featured on Death Valley Days which was hosted by Ronald Reagan. Some people I have met have questioned if this product would control anobiid, because the pest is deep inside the lumber. But Dan says that it is incredibly effective with the anobiid beetle and other pests too. The chemical is applied by an applicator on the wood in the crawl space and Dan said that one treatment should be enough. Unless the area floods, the borate stays in place and stays effective!
The catch though is that it does take some time for it to eliminate the whole beetle infestation. The biology is that the adults exit the wood, lay an egg as they leave and the larvae hatches from that egg and crawls down in a crack in the wood and there it feasts for five or more years. That is what does the real damage. And at any given time there might be a number of larvae down in the wood and they will mature and exit as adults at different times. As I understood it, the primary control takes place because the new eggs will not hatch. The adult may exit and lay an egg on the surface, but that will end the cycle of chewing as the larvae will not hatch or will die. This might take some time to get rid of them, as they live down in the wood for their five years, but they will die off. Part of the solution, as is always the case, is to provide adequate ventilation and reduce moisture in the crawl space. We call it eliminating conducive conditions.
Problem: The rub is that, if the wood is already badly damaged when the control begins, you will still have a significant problem because the wood is structurally shot. And, as is usually the case, sellers want to think that all that needs to be done is pest control when in fact the wood is soft, weak and in need of replacement in some areas.
I posted a bit of information on borate below. It is a very popular control today, after years of using DDT, chlordane and some of the others from a toxic past. Please note the line below that states that since 1953 it has protected homes in New Zealand. Dan said it would be a great improvement to our homes in the PNW if they had such a pretreatment in the crawl space when they were being built. The photo below is from an anobiid infestation. This wood needs to be replaced. It is too late for treating this joist.
Sodium borate is a form of boric and is applied on the wood, thereby eliminating most soil, air or water contamination. Sodium borate penetrates throughout the wood and leaves no toxic surface residue. The sodium borate is left as micro-crystals of borate salt inside the wood which will not decompose or volatilize (vaporize) like volatile, synthetic residual pesticide poisons. This means the sodium borate will keep providing you broad spectrum protection (permanently) with little impact on our environment or your health. Since 1953 when non-volatile sodium borate was mandated in New Zealand to be used to treat and pretreat lumber and homes and buildings, there has never been any evidence of even one successful attack of wood destroying organisms in New Zealand, no matter what the conditions.
Thanks for stopping by.
Steven L. Smith
Bellingham Home Inspector