A biblical plague or a winged love story? The Truth About California’s Annual Termite Schools | news


This story originally appeared in Redwood City Pulse, the new sister publication of Palo Alto Online, which was released on October 13th.

When the first autumn rain hit Redwood City this weekend, another environmental event caught local residents’ attention. One day after the first rainfall, swarms of flying termites were seen seemingly out of the blue.

So does the rains really trigger a termite explosion in early autumn?

“Absolutely,” said Andrew Sutherland, the Bay Area urban integrated pest management consultant at the University of California Agriculture and Resources. “Most likely, schools of western subterranean termites are being observed.”

These events happen once or twice a year depending on the region, with autumn swarms being more common in the Bay Area, according to Sutherland. And despite their resemblance to a biblical plague, they’re more of a regional romance.

“Because they live underground, they must have opportunities to meet and fall in love,” Sutherland said. “So it’s kind of a big single bar up in the air.”

As social insects, termites live in large, communal colonies of a few hundred to a few million individuals. Sutherland said they rely on these annual “wedding flocks,” which are a time for the “reproductive members of the colony to go, find a mate, and start their own colony.”

These wedding flocks are usually a single event, which residents have observed occurs on a calm, sunny day after the first autumn rains. When conditions are right, any winged virgins or “alates” who have waited near the surface of their colony leave en masse in search of a mate from another colony. However, unlike bees and ants, termites mate for a lifetime.

“The king and queen form what is known as a wedding couple,” said Sutherland. “And this wedding couple sets up a colony, usually in a piece of wood that is partially buried in the ground.”

Not every couple successfully sets up a new colony – some are eaten or unable to find a suitable location – but these huge schools have the potential to create thousands of new termite settlements.

Why the rain triggers their pilgrimage, Sutherland suspects that this has something to do with the effect of moisture, which makes the earth softer.

“I suppose it’s because the damp makes it easier for them to dig out their wedding chamber,” he said. In other words, wet soil and wood are easier to dig through and use up.

“Because we have a Mediterranean climate, this is the start of the rainy season, which means they will have more access to soil moisture in the coming months.”

Rather than destructive pests, however, Sutherland said, termites are largely peaceful roommates and vital ecosystem engineers.

“These are native insects, so they were here before us,” he said. “And they can often live next to us without threatening our home.”

Since much of the South Bay was built on orchards, there is an abundance of dead roots and trunks underground, which are ideal food and shelter for termite colonies. So the insects not only colonize these subterranean environments, but also help shape and nourish them.

“They are incredible decomposers of plant material,” said Sutherland. He said termites can remove up to a third of the dead wood and leaves that fall each year in some ecosystems. This aids in soil turnover and loosens the soil to make it easier for water to enter. In addition, termites are an important source of food for birds, lizards, and other species. Sutherland described their wedding crush as a “buffet”.

For those still in a panic about the thousands of termites that settle on their property, Sutherland said most modern homes were built to prevent infestation. Local building codes prevent wood from coming into direct contact with the ground, making it difficult for termites to dig from their underground colonies to the foundations of a house.

“We have made a lot of observations where we have large colonies of termites in a garden, right up to the house, but the house is never infested,” he said.

Nevertheless, he recommends a regular inspection every three to five years just in case.

“That’s all you can do to prevent it,” he said. “This is a very, very common native insect, it’s everywhere. So chances are they’re already in your yard.”

For more information on pest management and ongoing searches, see the University of California’s Integrated Pest Management Program Underground termite pest notes, a research-based guide to pest control for termites in California and the UC Agriculture and Natural Resources Blog article on Andrew Sutherland’s research project to investigate spring versus autumn swarm termites.

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