After Frank Bibin helped his pecan orchard kick the chemicals, he started on the sweetcorn field. His allies in this effort are bats — lots of them. About 4,000 a night, give or take a grand.
For nearly a decade the bats, with some daytime help from paper wasps, have controlled pecan nut case bearer, fall webworm, walnut caterpillar, stinkbugs, twig girdler and hickory shuck worm, saving the farm more than $1,000 each year in pecan pesticide costs. But economics weren’t the reason Bibin started looking for alternative pest control when his family moved to the south Georgia farm in 1994 and discovered that the pecan trees were on a conventional spray program.
“Spraying was one of the most awful experiences of my life,” he recalls. “It smelled terrible. The law required a 24-hour yard restriction after every spraying, but even that didn’t seem like enough. I wore protective clothing, masks and gloves. Still it was always splashing on me when hoses broke or spray tips clogged. We found dead birds after every spraying.”
Bibin built his first bat house after reading about the flying insect gobblers in 1996. It sat empty for two years, but finally in March 1998, 25 bats took up residence. He kept building; they kept coming. Today more than 20 bat houses host up to 4,000 bats during the warm months. Since each bat eats about half its weight in insects (about 6 grams), Bibin estimates they wipe out about 50 pounds of insects each night. Within three years of the bats’ arrival, the orchard was operating insecticide-free.
The guano that piles up on the ground beneath the bat houses is an added benefit of the arrangement. Before the advent of chemical fertilizer American farmers imported tons of guano to feed their crops and it is once again in favor as more farmers transition to organic production. Between the free organic fertilizer and the free organic pest control, organic certification has been less costly for Bibin than for most would-be organic farmers.
Bats have done so much for his farm that Bibin became a spokesperson on their behalf, working to dispel some of the myths that associate bats with rabies, hair-tangling and even vampires. Schools and scout groups invite him to speak and to supervise civic installations of bat houses for insect control in public places. He became a research cooperator with Bat Conservation International (BCI), counting bats and recording observations of their behavior around the farm. Television crews from France and Britain have visited the farm to shoot footage for documentaries. Scientists from universities and researchers from the Centers For Disease Control and Prevention (CDC) are among those who conduct studies at the farm. And that brings us back to the sweetcorn.
It was a red-letter day for Bibin when bat guano from his farm tested positive for corn earworm DNA as part of a study conducted for the CDC by Dr. Gary McCracken. While pecan pests affect only a small number of farms, corn earworms infest thousands of acres on farms in just about every state. Typical spray schedules are on three- or four-day intervals, using organophosphates or pyrethroid-based insecticides. (Learn more about these pesticides here.) Bibin had suspected that Mexican free-tail bats ate a lot of corn earworm moths; this was his chance to find out if they could help a farmer reduce or eliminate pesticides for corn earworms.
In 1999 Bibin had obtained a SARE producer grant to evaluate the potential for bats and wasps to protect his pecan orchard without chemicals. In 2006 he submitted a new proposal to test their effectiveness against corn earworm. He was awarded a little less than $1,000 to cover the expenses of growing a quarter acre of organic sweetcorn as well as data collection and analysis. A control plot of sweetcorn was grown in a nearby Tift County.
Both plots were planted with early, middle and late crops of sweetcorn. Each plot was monitored for corn earworm damage. Samples from the conventional site showed an average of 53 percent corn earworm damage between June 14 and July 5. On Bibin’s plot from June 24 to July 8, there was an average of 26 percent damage, roughly half as much.
There was no middle or late crop at the conventional site for comparison, but Bibin saw his earworm damage rise to 39 percent in the middle phase (July 8 to July 21) and to an average of 98 percent in the late phase (July 22 to July 28), indicating the bats did not control corn earworm in the late phase.
Brooks County Cooperative Extension agent and project cooperator Johnny Whiddon believes the high infestation during the late phase was due to the large increase in corn earworm moths at that time of the season. Approximately 5,000 acres of unsprayed field corn had been planted for silage in the county and the new generation of moths would have emerged in great numbers seeking suitable crops to lay eggs.
“If we could repeat this project, we would plant the corn two weeks earlier,” says Bibin. “We would also erect a new bat house closer to the corn plot because we have observed that as bats return to their roosts through the night there appears to be increased feeding activity closer to the roost.”
Frank and Teresa Bibin welcome individuals, classes and other groups to see the diversified organic farm and pecan orchard dotted with bat houses, wasp houses and vermicomposting worm bins. For details contact the Bibins by phone (229-775-3347) or e-mail.
Add simple bathouses to your property to provide shelter for these beneficial creatures.
See Also: Fantastic Bats
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