For those living in and around the New Orleans metro area, the beginning of May is a fairly reliable indicator the fleeting southeast Louisiana spring is quickly coming to an end.

As temperatures begin to climb and air conditioning usage sends energy bills soaring, the arrival of May — specifically, the days surrounding Mother’s Day — brings the promise of sweltering heat, pesky mosquitoes and, most frightening to many, swarms of Formosan subterranean termites. 

This year appears to be right on track, despite a record-cold winter and mild spring that had many hoping for a reprieve from the winged pests. As the annual New Orleans Jazz and Heritage Festival was winding down last weekend, swarms of Formosan termites — looking for love and emboldened by the humid, breezeless nights — kicked off their annual swarming.

Hugging lamp posts, crowding around porch lights and fluttering near light bulbs and bedside lamps, huge numbers of the wood-eating insects were captured on social media, with sightings reported all over the metro area, including Metairie, Mid-City, Faubourg St. John and Uptown.

Termites were spotted as far afield as Des Allemands, where entomologist Zack Lemann stumbled upon a swarm of “tens of thousands” while leading a bug collecting trip Sunday evening.

Lemann, who is the curator of animal collections at the Audubon Butterfly Garden and Insectarium, said the timing and size of that flock could mean the largest swarms — which normally show up right around Mother’s Day — may already have passed.

“If you look at a bar graph of when the activity starts to hit, you get a big noticeable night, a second big noticeable night, and then — Kaboom! I believe we might have had that blast last Friday, Saturday, Sunday,” Lemann said.

Still, the swarming season, typically running from May to July, is far from over, he said. This is when the male and female alates, as they’re called at this stage, fly from the colony where they were born and swarm for the purpose of finding mates.

Though there is no exact answer for why the swarms tend to peak in early May, the environmental factors that appear to excite the insects’ reproductive itch are usually very humid and windless nights, often following a rainstorm, especially between 7 p.m. and 9:30 p.m.

First introduced to the U.S. in the 1940s and ’50s, the Formosan termite is native to East Asia and wasn’t discovered in Louisiana until around 1965. Roughly 20 years before that, researchers believe, the first Formosans arrived via military ships that transported crates and cargo during World War II to Camp Leroy Johnson — now the University of New Orleans' East Campus — and the Algiers Naval Support Activity.

From there, the insects spread rapidly; New Orleans remains one of the most heavily infested areas in the state.

Because the termites flourish in warm, muggy conditions, they are mainly found across the American South but are also present in Hawaii, where they were introduced earlier than on the U.S. mainland.

Formosans can average 10 million per colony and are drawn primarily to damp wood in homes and trees.

Although last winter, the region experienced some of the coldest weather in recent years, the cold snaps and freezes that caused road closures and burst pipes won’t affect the termite or mosquito seasons much, experts say.

Weather below 55 degrees will slow down insects, causing them to temporarily cease most of their activity, Lemann said. But it won’t necessarily kill them or have any lasting effect on their life cycle, he said. Termites, in particular, are sheltered from the cold by living beneath the soil, where the temperature is fairly constant, and inside of trees and houses, which are insulated against the elements.

“Cold weather is typically not something that will knock down termite or mosquito populations. It will just create a longer period when they are not active,” Lemann said.

For homeowners and those looking to best keep the swarms from getting inside their houses, the old adage still applies: Turn out the lights and wait for the swarm to pass. 

That tactic doesn’t work quite as well with mosquitoes, which are a nuisance but almost impossible to avoid during the summer months in southern Louisiana.

Across the metro area, mosquito abatement programs are in full swing. Most programs launch in March or April and sometimes last until November.

In St. Tammany Parish, the abatement program includes deploying a new type of mosquito trap that counts the number of insects that enter it. The captured specimens can be viewed in real time online, which allows the program’s managers to better target the time of night when spraying is most effective, said Kevin Caillouet, director of the St. Tammany Parish Mosquito Abatement District.

Roadside ditches, where stagnant water is a fertile breeding ground for the pests, are treated using a new mapping technology that shows how often and where mosquitoes are hatching. “The new technology and new treatment regimes enable us to more selectively and efficiently kill mosquitoes before they become biting adults,” Caillouet said.

Similar abatement programs in Orleans and Jefferson parishes include spraying, ground and aerial surveillance operations, larvae sighting and tracking, and educational efforts.

With the Centers for Disease Control and Prevention reporting earlier this month that illnesses from mosquito, tick and flea bites had tripled in the U.S., surveillance operations — which employ traps and subsequent laboratory testing — are key in determining and minimizing the risk to residents, said Dr. Claudia Riegel, director of the New Orleans Mosquito, Termite and Rodent Control Board.

“It’s a lot of time and effort and manpower, but it pays off in prevention,” she said.

Other safeguards that residents can take include wearing long-sleeved clothing, frequently applying insect repellent and getting rid of any standing water on their property. 

"It’s always a great reminder to tell people to walk around the yard once a week and turn over containers," Riegel said. 

Follow Helen Freund on Twitter, @helenfreund.