Gardeners' Dirt: A thanks to 'amazing, mysterious' bats

March 23, 2010 at midnight
Updated March 23, 2010 at 10:24 p.m.

One Mexican free-tail bat can eat as much as  of its body weight in bugs each night.  No wonder bats have been considered the greatest natural ally of the agricultural industry with the enormous numbers of insects they consume during their nightly jaunts.

One Mexican free-tail bat can eat as much as of its body weight in bugs each night. No wonder bats have been considered the greatest natural ally of the agricultural industry with the enormous numbers of insects they consume during their nightly jaunts.

When I grew up, bats had a bad reputation. Back then, people believed all the nonsense Hollywood churned out about these shy and gentle little creatures. Bats' naturally secretive nature only reinforced all the B movie "guano" perpetuated about them. As a result, it was easy for humans to believe the worst of these furry little fliers.

Things didn't look so good for bats until organizations like Bat Conservation International came along. Because of this and other groups, we now know just how amazing these little creatures really are. For example, in some parts of the world bats are so important, they are considered "keystone" species in maintaining the health of local ecosystems.

In North America, they are acknowledged as the greatest natural ally of the agricultural industry because of the enormous numbers of insects they consume at night. In many parts of the world, bats are instrumental in seed dispersal of native plant species, and also pollination of many types of fruits and flowers.

We now know that if it weren't for bats, many of the things we enjoy and take for granted today would simply not exist.


Most bats living in North America are insectivores. One Mexican free-tail - the most common species around here - can eat as much as of its body weight in bugs each night.

To put that in perspective, that's like a 150-pound person eating 450 hamburgers every day.

Large bat colonies can literally eat several tons of insects every night. Think about what life would be like for us if bats weren't around to take care of all those insect pests.


A few years ago, improvements in Doppler technology allowed meteorologists to observe radar images of huge clouds of "something" that appeared regularly at very high altitudes in the evening skies.

A bit of investigation proved the clouds to actually be vast numbers of bats. Puzzled as to why the bats were flying so high, scientists set out to discover just what the tiny fliers were up to - and their discovery benefited our understanding of the contributions bats make to the American agricultural industry.

It turns out, bats feed voraciously on high flying swarms of cotton bollworm moths, or corn earworms and fall armyworm moths, insects known to ravage corn and cotton crops. Thanks to Doppler, we now know that bats are incredibly successful predators of the very insects that humans largely failed to do away with through pesticides.


While most bats in North America are insectivores, a few nectar and fruit-eating bats exist here, tool, with many more just south in Central and South America. These bats are just as important as insectivorous bats when it comes to plant species upon which humans depend.

For example, avocados, bananas, peaches, figs and agaves, rely primarily upon nectaring bats for pollination. As bats move busily from one flower to the next in search of tasty nectar, the pollen dusting their little heads pollinate each new flower visited. And voilé - we have avocados.

As for fruit bats, studies conducted to determine viability of seed from consumed fruit have shown seeds that pass through a bat's system germinate more quickly than seeds that do not. Fruit bats tend to fly widely in search of food, and scientists discovered they play a significant role in reforestation because of seeds distributed along with their guano.


Speaking of guano, we've all heard that bat poop is good for gardens - but why? Guano consists of about 10 percent nitrogen, 3 percent phosphorous and 1 percent potassium. Plus, it has plenty of the micronutrients relished by plants.

Additionally, it builds up sandy soil, makes compact soil friable, and the microbes found in it help combat plant diseases and pests.

Reputable companies harvest guano from caves and roosts during months when bats are on their migratory path. The guano is then packaged and sold to gardeners.


Like many wildlife species, bat populations are in worldwide decline. Vandalism, as well unintentional disturbance by humans, took a toll on bat populations everywhere, with maternal colonies of mothers and babies being particularly sensitive to human interference.

Fortunately, several species of bats in the United States are now federally protected, and in Texas, all bats are protected by state law, so at least some measure of protection is now in place in this country.

With increasing awareness by the general public about the tremendous role bats play in insect control, pollination and seed dispersal of wild plants and agriculturally important crops, it is hoped that the future of bats - in this country at least - will improve.


So, the next time you slip into some comfortable cotton clothing and sit down to a meal that includes corn, guacamole or a tasty slice of peach pie - thank a bat. Consider repaying bats for their service to humans by hanging a properly-constructed bat house somewhere on your property to give them a comfy place to hang out during the day. They can be small housing for 10 to 50 bats like the plans at or approach the largest size bat house in the world for 250,000 bats that County Extension Agent Joe Janak toured in 2002 in Gainesville, Fla.

Then, on some warm summer evening as the sun begins to set, take time to kick back and enjoy watching your friendly neighborhood bats flit, fly and gobble up a plethora of pesky insect pests.

The Gardeners' Dirt is written by members of the Victoria County Master Gardener Association, an educational outreach of Texas AgriLife Extension - Victoria County. Mail your questions in care of the Advocate, P.O. Box 1518, Victoria, TX 77901; or, or comment on this column at



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