My wife and I like to sit on our back porch and watch the sunset each day. We do not make all of them, but we try to make as many as we can. We often see small bats darting in all directions feeding on bugs. Recently we were enjoying a particularly great sunset. The sky was a light blue with streaking clouds of dark gray, purple, orange, and white. It was amazing. As the streetlight came on, we could see a swarm of termites gathering around it. There were a lot of them, but we also noticed the increase in bats. There was a dozen at least, probably more, zipping in and out, darting in all directions. We enjoyed watching them and wondered where all of them were roosting.
Bats sometimes move into buildings when they can’t find the natural structures they prefer (caves and large trees with cavities).
Many people are afraid of these creatures. They have been associated with Halloween, horror, vampires, and rabies. They are creatures of the night, and that is unsettling in itself for many. But, as biologists say with most creatures, these stories and legends are just that… stories and legends. Some members of their population do carry rabies, but most do not and the transmission of the disease to humans is rare. The animals are small furry mammals that eat an enormous number of insects each evening, including flying termites and mosquitoes. Many help pollinate plants and help disperse seeds. They are really pretty cool.
There are around 1400 species of bats worldwide1, 13 of these are from Florida2. Though some species feed on fruit and nectar, most feed on insects and consume about half their body weight each evening doing so. The Bat Conservation International states that insect consuming bats may save U.S. farmers $23 billion dollars a year in pesticide use due to their insectivorous diet1. The agave plant, the one used to produce tequila, is primarily pollinated by bats. The 13 species found in Florida are all insectivores feeding on beetles, mosquitos, moths, and other agriculture and garden pests. They are truly beneficial.
Bats are mammals, having fur covered bodies, live birth with young nursing on milk, and being endothermic (warm blooded). Most connect bats with the mammalian order Rodentia (rodents) – often calling them “flying rats”, but – due to the type of teeth – they are actually in their own order Chiroptera. They are the only true flying mammals in the world, the flying squirrel is actually a glider, not a true flyer. They live in a variety of habitats in Florida including pine forests, hardwood forests, riverine systems, lakes, and in urban areas. They most often roost in the crevices of dead trees, beneath the dead fronds of palms, and in Spanish moss. But when available, they will use caves and are notorious for using buildings, culverts, and the underside of bridges.
They fly using wings that are actually thin skin between their extremely elongated fingers. They breed in the fall and give birth to a single pup in the spring. One of the legends is that they are blind. As mentioned above, this is a legend. Bats can see well and see better than we do in dim light. They do have the ability to use high frequency sounds to “echo” off objects in the dark (echolocation) which helps them find, and follow, their insect prey at night. You can notice this hunting tactic as the sun sets and view the bats darting in all sorts of directions chasing their prey.
Most of the 13 species of Florida bats can be found in the Florida panhandle, with the gray bat only found in Calhoun and Jackson counties and nowhere else in the state. Rabies is a concern with bats, and it is true that an infected bat with the disease can transmit it to humans, but this is very rare. That said, anyone who is bitten by a bat should seek medical attention. The animal was also connected with the transmission of COVID during the early period of the pandemic3. Bats, like many other mammals, can pass infectious diseases and there is also a fungal growth associated with their droppings that has caused medical problems with some humans. If working in an area where bat guano is abundant, a mask is recommended. If an injured animal is found in your yard, wear a pair of gloves and take it to your local wildlife rehabber.
Florida bats do face problems in our state with the loss of habitat. We often remove dead trees and cut dead fronds from palms. The benefit we receive from them (consuming thousands of pest insects each night) leads to a need for their conservation. To date, the white-nose syndrome, which has infected many bats north of us, has not reached Florida but is of concern. Despite the fear many have of this animal, they are quite beneficial and should be allowed to exist in our panhandle habitats.
Species found in Florida:
Mexican Free-tailed bat
Southeastern myotis
Evening bat
Eastern red bat
Seminole bat
Northern yellow bat
Tricolored bat
Gray bat – endangered; only found in Calhoun and Jackson counties.
A wildlife biologist feeds an overwhelmed mother bat and her young after they were found on the ground. Photo credit: Carrie Stevenson, UF IFAS Extension
As we enter Halloween season, one of the most popular images of this spooky time of year is that of a bat. The creepy tales of vampire bats and Dracula are enduring and certainly exciting. Unfortunately, many negative connotations exist around this fascinating species. Perhaps you’ve heard they carry rabies, that they will fly into your hair, or that many of them are considered blood-sucking vampire bats?
In fact, there are many benefits to having bats in one’s landscape and neighborhood. The predominant role of bats in our local ecosystem is that of insect predator. A single little brown bat (Myotis lucifugis), which is native to the Florida Panhandle, can eat 1,200 mosquitoes in one hour of feeding! Other species in warmer climates eat fruit and play a major role in reforesting rain forests in Central and South America—after digesting the fruit they leave seeds in their droppings (guano is excellent fertilizer, by the way), helping replant 95% of the very trees they feed upon. Some species feed on nectar, filling the same role as bees and helping pollinate bananas, avocados, cashews, and figs.
Contrary to popular opinion, vampire bats lap up blood from minor cuts on livestock and do not attack or kill them.
Despite the old saying, bats are not blind and many have excellent vision. However, they do rely heavily on echolocation to sense prey and are extremely accurate hunters. They often fly erratically because they are chasing very small flying insects, so the only reason one would end up in a person’s hair is if a mosquito flew through it with a bat in chase! While vampire bats do exist, there are only 3 out of over 1,000 species of bats that feed on blood, and they all live in Latin America. They typically consume blood from livestock by breaking the skin with their teeth and lapping up blood like a cat drinking milk.
Human contact with bats is rare unless the bats are sick, which is why one found on the ground should be left alone. Rabies transmission from bats accounts for only one death per year in the United States—a statistic much less than that of deaths from dog bites, bee stings, and lighting strikes! In fact, several towns in Texas with the highest populations of bats in the country have recorded zero human bat-transmitted rabies cases. If a bat is obviously injured or has pups with it, most wildlife sanctuaries will take them in and give you special instruction on how to approach them.
Building bat houses is a great family activity and helps provide much-needed habitat for bats. Photo credit: Carrie Stevenson, UF IFAS Extension
Bat populations are declining in North America due to disease (particularly white-nose syndrome), loss of habitat, and the slow reproductive cycle of bats. However, you can help the world’s only flying mammal by installing a bat house in your yard. Keep in mind that bats attracted to bat houses prefer to be in open areas away from trees (where their predators hide), and the house should be installed at least 12 feet in the air. Bat houses can be purchased or built rather simply—keep an eye out for Extension workshops near you, or visit Bat Conservation International’s website for simple instructions.
Insect pests can destroy substantial quantities of crops, prompting growers to invest heavily in pesticide use. Previ
These three common species of bats in FL, GA, and AL eat insect pests notorious for causing substantial damage to crops: the Seminole bat (Lasiurus seminolus), southeastern bat (Myotis austroriparius), and evening bat (Nycticeius humeralis) (photo credits @MerlinTuttle.org).
ous research in Texas suggested that bats could reduce pesticide costs by over a million dollars within their state, due to the bats’ fondness for pests that damage cotton. Scientists at UF/IFAS recently collected evidence locally that indicates bats are providing valuable assistance with pest reduction for many of the crops grown here too.
During spring and summer of 2018 scientists at UF clarified what the common species of bats were eating in north Florida, south Georgia, and south Alabama. We investigated 161 bats across 21 counties and found that 28% of these bats ate at least one Lepidopteran (moth) pest species, 21% ate a Coleopteran (beetle) pest, and 18% ate a Hemipteran (true bug) pest. In total, 12 different species of agricultural pest species were eaten by these bats.
The moth pests consumed by bats were:
Green Cutworm Moth (Anicla infecta)
Tobacco Budworm (Chloridea virescens)
Soybean Looper (Chrysodeixis includens)
Garden Tortrix (Clepsis peritana)
Lesser Cornstalk Borer (Elasmopalpus lignosellus)
Corn Earworm (Helicoverpa zea)
Beet Armyworm (Spodoptera exigua)
Fall Armyworm (Spodoptera frugiperda)
Red-Necked Peanutworm Moth (Stegasta bosqueella)
The beetle and true bug pests consumed by bats were:
Hairy Fungus Beetle (Typhaea stercorea)
Tarnished Plant Bug (Lygus lineolaris)
Two-lined Spittlebug (Prosapia bicincta)
Three of these pests (Soybean Looper, Beet Armyworm, and Two-lined Spittlebug) were most often consumed by pregnant and juvenile bats. This is good news for growers of crops affected by these pests because you have a sound option for increasing the likelihood of bats helping control them. The trick is to provide the conditions that adult female bats like near the crops these pests feed on (e.g., soybeans, peanut, cotton, corn, sorghum, safflower). Most female bats pick a maternity roost in early spring. A maternity roost is a structure that provides warm, dry, dark conditions for female bats to sleep in during the day, and it is ultimately where they give birth to pups. When selecting a site to set up a maternity roost, female bats look for structures that are large enough to provide shelter for a large number of bats. A roomy structure can accommodate many bats, which allows the flightless pups to keep each other warm while the mothers fly in search of food at night. Installing a bat house like those shown here can provide conditions appropriate for a maternity colony, increasing your chances of having bats help control these insect pests.
Another useful strategy for enhancing pest control services by bats involves creating or maintaining structures that could serve as natural roost sites for bats. The natural structures bats prefer include large trees with cavities, dead and dying trees with peeling bark, oak trees with Spanish moss, and palm trees allowed to maintain their dead fronds. In agricultural areas and suburban areas these types of trees are often in short supply.
Maintaining large, old trees of a mix of species, and supplementing with bat houses, can help ensure there are plenty of roosting options for bats. This, in turn, will increase the likelihood that bats are available to assist with your pest management.
The week prior to Halloween is officially designated as National Bat Week. In honor of this event, it’s worth considering some of the benefits bats provide to us.
Did you know there is a species of bat that lives nowhere in the world but within our state? It’s called the Florida Bonneted Bat, and occurs in only about 12-15 counties in south and central FL. These bats are so mysterious that we’re currently not even sure exactly where they occur. They are so rare that they’re listed as a federally endangered species.
The Florida Bonneted Bat lives nowhere in the world but Florida. Photo credits: Merlin Tuttle.
These bats were named for their forward-leaning ears, which they can tilt forward to cover their eyes. With a wingspan of 20 inches, they are the largest bats east of the Mississippi River: only two U.S. species are larger than they are, and these both occur out west.
We have been investigating the diet of Florida Bonneted Bats. To do this, we captured bats in specialized nets, and then collected their scat (called guano). Next, we processed the scat in a laboratory using DNA metabarcoding to determine which insect species the bats had recently consumed.
We found that the bats eat several economically important insects, including the following:
fall armyworm (Spodoptera frugiperda)
lesser cornstalk borer (Elasmopalpus lignosellus)
tobacco hornworm (Manduca sexta)
black cutworm (Agrotis ipsilon)
These insects are pests of corn, cotton, peanut, soybean, sorghum, tobacco, tomato, potato, and many other crops.
Furthermore, the bats did not eat these insect pests infrequently. In fact, 86% of the samples we examined contained at least one pest species. On average, each sample contained three pest species! This tells us that Florida Bonneted Bats should be considered IPM (Integrated Pest Management) agents.
Currently, a new student has begun investigating the diets of bats more commonly found in northern Florida, southern Georgia, and southern Alabama. By the time Bat Week 2019 rolls around we’ll have details on which insect pests these bats could eat on your property.
If you’re interested in helping bats or incorporating them into your Integrated Pest Management efforts, consider creating roosts for them (places where the bats can sleep during the day). Bats roost not only in caves, but also in cavities in trees, in dead palm fronds, and in bat houses.
Bats sometimes move into buildings when they can’t find the natural structures they prefer (caves and large trees with cavities).
All 13 species of bats that live in Florida sleep during the day and feed on insects throughout the night. Most of these bats sleep in natural structures such as trees and caves. But when the natural structures these bats prefer are limited or vandalized, the bats may move into buildings.
Bats are a great help to us. Each of them consumes hundreds of insects per night. Bats save growers billions of dollars annually by reducing insect pests. Some of the pests bats feed on include the damaging fall armyworm, cabbage looper, corn earworm, tobacco budworm, hickory shuckworm, and pecan nut casebearer. But both bats and humans are happier when not sharing living spaces!
If you or someone you know has a group of bats living in a building where they are not welcome, you have options. The safe, humane, effective way to coax a colony of bats out of a building permanently is through a process called an ‘exclusion’. A bat exclusion is a process that prevents bats from returning to a building once they have exited at sunset to feed. This is accomplished by installing a temporary one-way door. This one-way door can take many forms, but the most common is a sheet of plastic mesh screening (with small mesh size of 0.125 x 0.125 inches or less) attached at the top and along both sides of the sheet, and open on the bottom. Another option is to install slick tubes (such as clean caulk tubes) to such entry points. These temporary one-way doors should be attached over each one of the suspected entry/exit points bats are using to get in and out of the building.
It is illegal to harm or kill bats in Florida. However, excluding bats from a building is allowed if you follow practices recommended by the Florida Fish and Wildlife Conservation Commission (FWC). According to Florida law, all bat exclusion devices must be left in place for a MINIMUM of 4 consecutive nights with temperatures above 50⁰ F before each entry point can be permanently sealed to prevent bat re-entry. Also, it is unlawful in Florida to attempt to exclude bats from a building between April 15 and August 15, which is bat maternity season. This is when female bats form large colonies and raise young that are unable to fly for their first few weeks of life. If bats were excluded during this time period, young bats (pups) would die indoors.
Bats can be coaxed to leave a building by first identifying the bat’s entry points into the building, and then creating a temporary one-way door using plastic screening with fine mesh size over each of these entry points.
The steps for an effective exclusion are as follows:
Identify the locations where bats are getting in and out of the building. Look for holes or crevices about the width of your thumb, often near the roofline, with brown staining on the exterior of the building and bat scat (guano, about the size of a grain of rice and brown in color) below.
Fashion and install one-way doors at each suspected bat entry point. This can be done anytime between August 16 and April 14 – it cannot be done when bats have young pups, which is between April 15 and August 15.
Leave all one-way doors in place for at least 4 consecutive nights with minimum temperatures above 50⁰ F so all bats leave through the doors and cannot re-enter. If any one-way door becomes ineffective during the 4 day period, begin again. You must be absolutely certain all bats have exited so you do not block any inside the building.
Immediately after removing the one-way doors, permanently seal each hole to prevent bats from getting back inside.
For detailed instructions on how to conduct a bat exclusion, see this video that features interviews with bat biologists from the University of Florida, FWC, and the Florida Bat Conservancy: How to Get Bats out of a Building.
Remember, if you have a colony of bats roosting indoors that you want to exclude, you must either act within the next few weeks or else wait until the middle of August to coax them out. Bat maternity season in Florida runs from April 15 to August 15, and during this time no one can attempt to exclude bats from a building.
