Most bats worldwide, specifically the smaller species known as Microchiroptera, rely on insects as their primary food source. Approximately 70% of all bat species are insectivores, making them the most significant predators of nocturnal insects in nearly every ecosystem. As specialized, flying mammals, they have evolved unique sensory systems to locate and consume prey under the cover of darkness. This dietary focus establishes them as a component of natural pest control across diverse habitats.
The Primary Targets: Specific Insect Groups
The diet of insectivorous bats is diverse, dominated by four major orders of arthropods that include many agricultural pests. Moths (Lepidoptera) often constitute the largest portion of a bat’s nightly intake. Bats frequently target species like the corn earworm moth and the cotton bollworm, which cause hundreds of millions of dollars in crop damage annually.
Flies and mosquitoes (Diptera) are also regular prey, controlling populations of nuisance and disease-carrying species. For example, some bats consume flies like Psychoda albipennis, a parasite that can cause human intestinal issues. Many bat species also consume hard-bodied insects, such as beetles (Coleoptera), including the spotted cucumber beetle and the western corn rootworm.
The diet also includes true bugs (Hemiptera), such as various species of stinkbugs, which are significant agricultural nuisances. Bats target pests across multiple insect orders, including those with different flight patterns and body types, underscoring their generalist predatory nature. DNA analysis of bat guano confirms that a large percentage of the insects consumed are agricultural or forestry pests.
Hunting Strategies and Echolocation
Bats primarily locate insect prey using echolocation, a biological sonar system unique among mammals. They emit high-frequency sound pulses from their mouth or nose, which are outside the range of human hearing. The bat listens for the echoes returning from objects, constructing a detailed, three-dimensional image of the environment at night.
The returning echo provides information on the prey’s size, speed, and trajectory, enabling the bat to track and intercept the insect. As a bat closes in on a target, it rapidly increases the frequency of its calls into a “terminal buzz” to pinpoint the exact location before capture. Bats employ two main capture tactics: aerial hawking and gleaning.
Aerial hawking involves catching flying insects directly in the air, a common method for pursuing fast-moving moths and flies. Gleaning is a strategy where the bat picks a stationary insect off a surface like a leaf, the ground, or a water body. Some bats, like the barbastelle bat, use “stealth echolocation” by emitting calls at an amplitude up to 100 times lower than other aerial hunters to avoid alerting eared moths.
Consumption Rates and Ecological Importance
A bat’s high metabolism and nocturnal activity necessitate a substantial food intake each night. A single insectivorous bat can consume between 25% and 100% of its own body weight in insects during one night of foraging. For a small species like the little brown bat, this amounts to 4 to 8 grams of insects nightly.
This consumption rate scales up dramatically in large colonies. The Mexican free-tailed bats of Bracken Cave in Texas, for instance, are estimated to consume hundreds of tons of insects every summer night. This predation pressure provides an ecosystem service of value to agriculture and public health.
The economic benefit of bat insect consumption is calculated to save the United States agricultural industry billions of dollars annually by reducing the need for chemical pesticides. By targeting major crop pests like the cotton bollworm, bats act as natural biological control agents. Their continuous foraging helps suppress pest populations, protecting crops such as corn, cotton, and rice.
Specialized Diets and Regional Variations
While insectivory is the dominant diet among the Microchiroptera, the specific menu varies based on species, geography, and habitat. Some bats prefer certain insect types; larger species often consume a higher proportion of hard-bodied beetles (Coleoptera). Conversely, smaller bats tend to specialize in soft-bodied insects, such as moths (Lepidoptera).
Habitat also influences diet, as bats foraging over agricultural fields consume more crop pests than those hunting in forest environments. In tropical regions, the general diet of the order Chiroptera expands beyond insects to include diverse food sources. The Neotropical leaf-nosed bats (Phyllostomidae) have diversified to include species that feed on fruit, nectar, pollen, small vertebrates, and blood.