Insects may be a necessary part in the plan of nature, but they are also a problem for the gardener. Some of them eat the plants, and others prefer the gardener himself for dinner. Birds keep many of the undesirable critters under control, mostly during daylight hours. In the evening and at night bats feast on large numbers of unpleasant insects.

Bats are almost invisible visitors. A few may be seen in the twilight, and others visit the hummingbird feeders in the dark. If you shine a flashlight on the feeder, you may see an impressive number of nectar feeding bats during a few summer months here in Southern Arizona. For a few weeks to a month they will swoop down and dive past the hummingbird feeder taking a drink and sometimes leaving pollen grains stuck to drips of sugar water. For that short time be ready to refill your feeders each morning. It will probably be the hottest part of the summer, and the feeders need to be cleaned almost daily during the heat anyway. If you don't want to refill the feeders, bring them in before dark.

The only flying mammals are bats. They are quiet visitors having voices so high in pitch that we cannot hear them. They won't wake you as they busily clear away unpleasant insects. The insect eater bats have a diet of creatures such as moths, crickets, ants, and mosquitoes each night. After eating up to half its body weight in insects, the bat rests and digests the meal during the daylight. Then he is ready to hunt again with an empty, lightweight stomach.

There are so many bats around that it is surprising that we don't see them very often. The ones that spend the day sleeping in trees are well camouflaged. They look a lot like dry leaves or a tangle of branches. Most bats prefer to roost and sleep in caves, rocky ledges, and mines. A few kinds can be found under bridges and in hollow trees. Bats become a nuisance when they decide to roost in buildings. The best way to get rid of such a colony is to close up the openings that they use to fly away for the winter. Sometimes alternative housing can be constructed for the bats. In Europe, bats are protected and bat houses are used to draw the bats to wet areas and reduce the mosquito population. Our county office has plans for bat houses. A surprising small house will hold thirty to fifty bats. Here, though, where rabies is an annual problem, it would be best to check with an expert before tacking a bat box up in your back yard.

Our area is home to at least seventeen different species of bats. Each has its specific habitat and food. Some feast near water, others eat low flying or hopping insects. Some bats feed on higher flying moths. The "vegetarian" bats eat soft fruits, nectar, or pollen. As civilization encroaches upon the countryside, it is feared that some types of bats are becoming endangered species. One species that lives in caves of the Huachuca Mountains is definitely declining. It is a nectar eating bat which may be the sole pollinator for the local agave. As the agaves, which grew in abundance close in Mexico, are dug for bootleg tequila production, the bat numbers decline. Then as a result, pollination of the remaining agave plants is reduced. As the evening pollinator disappears, so does the beautiful white agave flower.

Kartchner Caverns State Park, has a large bat population.  The population is being stressed by disease and other factors but still uses the caverns for their nursery.  More about this type of insect eating bat can be found here.