Swarming Season

Heavy swarms of Formosan subterranean termites in South Mississippi in May created lots of buzz on social media.

Swarms appear primarily in coastal counties, but on the evening of May 13, a large swarm postponed a high school softball championship game in Hattiesburg.

Santos Portugal, urban entomologist with the Mississippi State University Extension Service, said the appearance of these invasive, cellulose-eating insects was right on time. Formosan subterranean termite swarmers appear in Mississippi late April through June. What caught people off guard was the size of the swarm.

“It was one of the largest swarming events that many Mississippians have seen in quite a while, and maybe ever,” Portugal said.

Formosan subterranean termite swarmers emerge for a few hours after sunset, often after a daytime rain event, to find a mate and start a new colony. In heavily infested areas, these swarmers can be a nuisance because they are highly attracted to light and swarm in the early evening, frequently interrupting outdoor nighttime activities.

“There are lots of factors that could contribute to heavy swarms like we saw [on May 13], including the recent rain. But most colonies of Formosan subterranean termites are larger than our native subterranean termites,” Portugal said.

“So, you’ll see a ton more swarmers. Formosan termites are invasive. And as they spread, they tend to outcompete our native subterranean termites. That is another reason that we may be seeing heavier swarms this year as they are establishing further north in the state.”

Compared to native subterranean termite swarmers, Formosan subterranean termite swarmers are larger, brown in color and have amber wings. Eastern subterranean termite swarmers are black with white to clear wings and swarm during the day from mid-February to mid-May.

“Formosan subterranean termites are primarily located in the southern half of the state, but we have native subterranean termites everywhere in Mississippi,” Portugal said.

Formosan subterranean termites are considered established in parts of 26 counties in south and central Mississippi. Other northern counties, including Lee, Oktibbeha, DeSoto, Lowndes and Lafayette, have isolated collections. Portugal said it is not known if these colonies continue to persist.

Kevin Ragon, associate extension professor of sustainable bioproducts, said native subterranean termites have an important job of keeping forests clean.

“Native termites are decomposing organisms,” he said. “Without them, our forest floors would be covered in limbs, down trees and other cellulose-based debris.” — Source: MSU Extension