Bats: Friends of Farmers and Gardeners

Insect pests can destroy substantial quantities of crops, prompting growers to invest heavily in pesticide use.  Previ

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.