Torrents of rain come to the Rio Grande Valley once or twice a year.

After a few days, the air is thick with hordes of mosquitoes. There’s no escaping — except to run screaming into a building swatting at your bare skin.

Nighttime comes; bats awaken, unfold their mammalian wings and soar through fields, neighborhoods and cities devouring tons of insects — including millions of those dreaded, possibly disease-carrying, mosquitoes — all night long!

The next day, behold! Fewer mosquitoes are piercing your delicate skin, sucking out your life-blood.

Come morning, the bats are safely tucked into the fronds of the thousands of palm trees dotting the Valley’s iconic landscape.

But wait — you’ve radically trimmed your palm trees — denuded them of all but a cluster of green fronds — getting rid of any chance of ever having a palm skirt!

A palm skirt, or beard, which hangs from untrimmed palms, is the preferred roosting place for bats.

From Corpus Christi to the Mexican border, it’s tradition to trim palm trees once or twice a year, leaving only about five fronds sticking straight up — like a (thin) shaving brush, some would say.

Trailer-loads of palm fronds are removed annually from trees in public parks and right of ways as well as residential yards.

Why? Because it’s been done that way as far back as living memory, and because people think this looks tidy.

Unfortunately, this tradition adds to the number one threat to bats: Loss of habitat.

Bats especially suffer from the loss of palm tree skirts.

Those dead-looking palm branches house legions of bats.

Because bats are night-fliers, most people are unaware of the healthy bat population we have in the Valley and the benefits of bats to our daily lives.

In a moderate climate like the Valley, bats roost in trees. In areas with few trees, many cavity-roosting bats roost in man-made structures like buildings or bridges.

Texas has the highest population of bats in the United States. Texas is home to the largest colony of bats in the world. On summer nights, hundreds of people gather to see the world’s largest urban bat colony — some 1.5 million bats — emerge from under the Congress Avenue Bridge in downtown Austin. Those Mexican Free-Tailed bats reportedly eat upwards of 10,000 pounds of insects, including agricultural pests. The bats migrate each spring from central Mexico to various roosting sites throughout the southwestern U.S.

Closer to home, the South Texas Border Chapter of Texas Master Naturalist offers occasional bat-watching field trips to the Conway street exit on Expressway 83. They meet in a parking lot across from the overpass on the north side of the intersection.

At dusk, they are rewarded with a similar experience to the bat watch in Austin, with bats emerging from the expressway bridge.

“The purpose of the field trip is to show people this marvel in our own local community,” said Elizabeth Perdomo, vice president and field trip organizer for the chapter. “To teach them more about bats and help identify what species roost in this area.”

Chapter members gather just before dusk. “When the bats start coming out, first it’s just a few — then more — then a huge mass —  then a few more — then done,” Perdomo described. “Pretty neat to watch. They circle, fly off, scatter and spread out over the entire area, eating insects all night long. They return in the early morning hours to roost again for the day. In fall, the bats migrate to Mexico.”

Most of the bats observed during the recent Mission field trip were the insectivorous Mexican Free-Tailed bats along with Northern Yellow, Silver-Haired and Hoary bats. Insect-eating bats consume three quarters of their body weight each night in insects.

In addition, bats are major pollinators of more than 300 species of fruit. In the Valley bats help pollinate fruits, such as bananas, avocados and agave. They help pollinate night-blooming cereus, moonflowers and other plants whose blooms open at night, require pollination to produce fruit and seeds, ultimately feeding other native critters and birds. And the beat goes on.

Mexican Free-Tailed bats breed August through October — but not without a place to roost, such as the skirts of palm trees or crevices in bridges.

Here, it’s incredibly easy to offer bat roosting sites — especially those of us who are somewhat lazy — because it basically starts with doing nothing!

That’s right, doing nothing to the palm trees, that is, as they cycle through their natural evolution of new growth to the eventual sloughing of dead palm fronds to the ground.

Please, be kind to these gentle, sophisticated creatures — the Valley’s bats.

And be kind to your palms trees by keeping the palm frond skirt around their trunks. You’ll be housing a few hundred bats through summer and fall, doing yourself, and your neighbors, a tremendous amount of good.

Bat Week is October 24-31. Valley nature centers will be offering workshops, presentations and educational materials to help promote bat awareness.

Useful websites that offer information about bats include http://batweek.org/education-event/, www.batcon.org.

A Wildlife Habitat Council site offers a bat webinar at www.wildlifehc.org.

https://statesymbolsusa.org/symbol-official-item/texas/state-mammal/mexican-free-tailed-bat

Google: Mexican Free-tailed bat images for a gallery of photographs.

Several points to consider in trimming palms:

When live, green fronds are cut off a palm, photosynthesis is reduced and the palm can become stressed. In hard times, like drought, freezing weather or disease pandemics, improperly pruned palms are at risk of an untimely death.

The skirt protects the palm’s trunk from sun damage, drying wind, freezing and insect attack.

Palm tree bark provides protection to the palm. Tree spurs, often worn by palm trimmers, pierce the bark allowing infectious diseases and insects to attack the tree.

If you must prune your palms, hire a reputable tree trimmer who is licensed, bonded and insured, and who will use only a ladder or cherry picker and not tree spurs.

Sterilize, disinfect and clean all pruning tools with alcohol.

Prune moderately in early spring, never in the heat of summer nor prior to winter freeze.

Leave about six inches of the fronds “boot” in place to protect the trunk.

(Palm-trimming pointers courtesy of AgriLife Extension Service, Cameron County Master Gardeners and the Palm Society of South Texas)