If you’ve found a bat on the ground or in your home, the most important thing to know is that you should not try to feed it yourself. Bats have highly specialized diets that vary by species, and feeding them the wrong food can cause serious harm. Your first step should be contacting a local wildlife rehabilitator. In the meantime, you can safely offer water and keep the bat warm while help is on the way.
That said, understanding what bats eat is useful whether you’re assisting a rehabilitator, caring for bats in a professional setting, or simply curious about these animals. Here’s what different bat species need nutritionally and what to do if you find one that needs help.
Most Bats Eat Insects
The vast majority of bat species are insectivores. In the wild, they hunt beetles, moths, mosquitoes, and other flying insects, often consuming impressive quantities each night. A small brown bat weighing around 8 grams can eat 1.5 to 3.7 grams of insects in a single night, depending on its life stage. Lactating females eat the most, consuming roughly 30% of their body weight each evening. Juveniles eat less, closer to 17% of body weight per night.
In captive or rehabilitation settings, insect-eating bats are most commonly fed mealworms. Crickets, fruit flies, superworms, and blowfly larvae are also used. But here’s the critical detail most people miss: store-bought insects alone are nutritionally incomplete. Mealworms and similar feeder insects are naturally low in calcium, and feeding them straight to a bat can lead to a dangerous calcium deficiency that causes brittle bones, fractures, and muscle spasms.
Why Calcium Matters So Much
Captive bats are highly vulnerable to calcium-related diseases, including a condition where the body pulls calcium from the bones to maintain blood levels. This leads to weak, deformed bones and can be fatal. The goal is a calcium-to-phosphorus ratio of roughly 1.5:1, but feeder insects naturally have far more phosphorus than calcium, making this ratio hard to achieve without intervention.
The solution used by wildlife rehabilitators and zoos is called “gut-loading.” This means feeding the insects a calcium-rich diet for at least three days before offering them to the bat. A common gut-loading formula mixes roughly equal parts wheat middlings and ground dry dog or cat food with about 30% ground calcium carbonate by weight. The insects eat this mix, filling their digestive tracts with calcium-rich material, and the bat then gets that calcium when it eats the insect. Some caregivers also use gels containing water and dissolved calcium to hydrate and supplement the insects at the same time.
Fruit Bats Need a Different Menu
Not all bats eat insects. Frugivorous species (fruit bats) feed on fruit, seeds, and pollen. Their favorites include figs, mangoes, dates, and bananas. In professional care settings, fruit bats are typically offered a maintenance diet that combines fresh fruit like mango or banana with milk powder, cereals, sugar, and a vitamin and mineral supplement.
Nectar-feeding bats have even more specialized needs. In the wild, they drink nectar from flowers, which is essentially a sugar solution. Research facilities caring for nectar bats prepare sugar solutions at concentrations around 18% to 27%, using mixtures of glucose, fructose, and sucrose to mimic the composition of the flowers these bats naturally visit. This isn’t something you can easily replicate at home, which is another reason professional care is essential.
What to Do If You Find a Bat
If you find a grounded or injured bat, resist the urge to feed it. Focus instead on three things: safety, shelter, and getting professional help quickly.
- Do not touch the bat with bare hands. Bats can carry rabies, and transmission can occur through bites or scratches. Use thick leather gloves or drape a soft cloth over the bat before handling it. If anyone, including children or pets, may have had direct contact with the bat, report the exposure to your local health department.
- Contain the bat safely. Place a soft cloth or kitchen paper in a small box or container with tiny air holes. Gently place the bat inside and secure the lid. A piece of cardboard taped firmly over the top works if you don’t have a proper lid.
- Offer water, not food. Place a very small shallow dish of water inside the container, no bigger than a plastic bottle cap. This gives the bat a chance to drink without any risk of drowning. Do not offer milk, fruit juice, or any food.
- Keep it warm and quiet. Store the container in a warm, calm area away from pets and children until a rehabilitator can take over.
If you’ve found a baby bat, warmth is the top priority. Place the box on top of a hot water bottle, but never let the bottle touch the bat directly. Skip the water dish for babies, as they can easily drown. Baby bats need hand-rearing by an experienced carer and cannot survive on any food you’d have at home.
Why You Shouldn’t Feed a Wild Bat Yourself
Even with the best intentions, offering the wrong food can cause more harm than the bat’s original injury. Feeding fruit to an insect-eating species can cause digestive failure. Offering insects without proper calcium supplementation, even for just a few days, can trigger metabolic bone disease. Baby bats need to be fed specific formulas at precise intervals, and incorrect feeding can flood their lungs with liquid.
Wildlife rehabilitators are trained to identify the species, assess its condition, and provide the exact diet it needs. Most areas have bat-specific rescue groups or general wildlife hotlines that can guide you over the phone within minutes. In the UK, the Bat Conservation Trust runs a national helpline. In the US, your state wildlife agency can connect you with a licensed rehabilitator. The fastest route is often searching “bat rescue” plus your city or county name.
Feeding Bats in Your Yard
If your interest is less about rescue and more about supporting bats near your home, the best approach isn’t putting out food directly. Instead, create conditions that attract the insects bats already hunt. Native flowering plants, especially those that bloom at night, draw moths and beetles. Reducing outdoor pesticide use keeps insect populations healthy. A small water feature gives bats a place to drink on the wing.
Installing a bat house on your property provides roosting habitat, which is often more valuable than any food source. Bats are extraordinarily efficient hunters and rarely need supplemental feeding in a healthy ecosystem. A single little brown bat can eat over a thousand mosquito-sized insects per hour, so attracting them to your yard benefits both the bats and your summer evenings.