Closed For Two Days

The National Park Service is closing Point Cabrillo Lighhtouse in California for two days next week to fumigate for termites. Also closed will be the adjacent assistant lighthouse keeper’s quarters.  A routine building inspection in June turned up evidence of the infestation. At least termites are a bit easier to deal with and control than marine shipworms, which have plagued a few lighthouses, including Cockspur Island and Morris Island Lighthouses.

The lighthouse and assistant keeper’s quarters,  built in 2004 to house the “Lighthouses of Point Loma” exhibit, will be covered in large tents for the fumigation planned for September 8 and 9. The buildings will have to be inspected again afterward to be sure the termites have been eradicated.

Termites and the Damage They Cause

The Western subterranean termite is a serious economic timber pest causing millions of dollars of damage throughout their range, which includes California, Washington and Oregon. It is estimated that more than 1 in 5 homes in the high activity areas have been or will be attacked sometime by these voracious insects.

They are highly destructive to douglas fir and other common timbers used in construction. They can rapidly eat out the internal sections of structural timbers - devouring mainly softer wood, and prefer to leave the harder sections. As a result, infested timbers are often left as a thin shell with a honey-comb of layered hollow sections packed with moist soil.

If it’s not the Western subterranean termite, it may be the Pacific Drywood termite. They the largest and most significant dampwood termite in the United States. They have been found up to 6,000 feet above sea level, but more commonly in the cool and humid coastal areas. Like where all lighthouses are located.

The Western drywood termite is another problematic species. Although the colony development is slow, severe structural damage may still be caused by the presence of multiple colonies. Drywood termites eat across the wood grain and create chambers, or galleries connected by tunnels. However, they are more likely to be in a structure made completely of wood with poor workmanship demonstrated by poorly fitted corner joints. Most lighthouses are well constructed.

Why Lighthouses May Be At Particular Risk

The colony nests of Western subterranean termites are usually located in the ground below the frost line, but above the water table. Mud galleries or “shelter tubes” are constructed across hard objects in order to gain access to timber food sources. Where moisture regularly collects inside the wall or other cavities of a lighthouse, the Western subterranean termite can develop a subsidiary colony nest which may not require contact with the ground to ensure it’s survival.

They build a central colony nest from which they construct underground tunnels that radiates 100 yards from that nest in search of cellulose (wood). They enter buildings through cracks in concrete or masonry and can travel under wood or tile flooring. They can get through gaps of less than 1/16 inch wide.

The Pacific dampwood termite will attack wood of all types throughout its range. Timber in contact with the soil or structures built near or over water are common targets. This species is known to be very tolerant of moist conditions, even being found in pilings subject to tidal flooding.

Annual Building Inspections Needed

All lighthouse groups should regularly inspect, or have inspected, evidence of termite infestation. And not only on the West coast. Termites can be found in all areas of the country, although they are more common in warmer climes. But then, the cooler North Eastern and Great Lakes lighthouses need to watch out for carpenter ant infestations also, which can cause nearly as much damage as termites.

Termies, Marine Shipworms, Carpenter Ants. Is there no end to the dangers facing our beloved beacons? 

Photo Credits:

• Pt. Cabrillo Lighthouse by puliarf. Some rights reserved.
• Termite Wood Damage by Ian Dunster.

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