In the last few years, the United States has experienced massive flooding events from storms and hurricanes including Harvey, Irma, and Maria, and in the Carolina’s, Matthew and Florence. We know about the devastation to people and property, but what happens to pests?
Pests are survivors. Many, especially rodents, will seek high ground to get out of floodwaters. Some insects, like fire ants, will float on water to survive. But do other insects such as subterranean termites all drown? The short answer is no.
Termites have been around for 200 – 250 million years and have survived a host of natural disasters including ice ages and the extinction of the dinosaurs. While flooding from a hurricane like Florence is devastating to us, it is not as devastating to termites. While some termite colonies are killed or reduced in number, subterranean termites have strategies to survive.
One survival strategy is in the way termites breathe, which works through a system of holes (spiracles) along the sides of their bodies. If necessary, a termite can close their spiracles for extended periods of time. One study (Forschler and Henderson, 1995) found that 50% of native subterranean termites submerged under water could survive over 19 hours!
Subterranean termites live in a three dimensional world, so if a portion of a colony is above the ground in a structure or a tree, they are likely to survive a flood. Like fire ants, termites have some ability to float or raft on water. I have found in my own studies that some termites can tread water for about 4 days!
Like the impact on termite populations themselves, floods can impact termite treatments. If a termite baiting system is installed around a flooded structure and the flood waters are contaminated with pollutants, the bait matrix can be tainted and compromised in terms of attractiveness to termites. In this situation, the bait and possibly even the bait housing would need to be replaced with fresh product.
Soil treatments may require retreatment or remediation if the soil has been eroded or shifted, or sediment is deposited over a treated area. Similarly, flood waters may cause chemical treatments applied directly to wood for structural protection to leech out, requiring retreatment.
If you have been impacted by a flood, start by making a thorough inspection of the flooded property/structures to determine if your treatment has been compromised. Your pest management profession can suggest appropriate steps for remediation if needed. Consulting with your insurance company is also a good idea. In South Carolina, the Department of Pesticide Regulation (DPR) is a good resource for termite treatment questions after a flood. See DPR’s memorandum: Guidance Document for termite control retreatments after hurricanes or a sustained, torrential rain event resulting in significant flooding:
Forschler, B. and G. Henderson. 1995. Subterranean Termite Behavioral Reaction to Water and Survival of Inundation: Implications for Field Populations (Environmental Entomology, Volume 24, Issue 6, pages 1592-1597