- Written by Clyde McMillan-Gamber Clyde McMillan-Gamber
Several kinds of creatures catch flying insects in midair during summer and autumn in southeastern Pennsylvania. Those species of winged wildlife are a variety of small birds, bats, and dragonflies.
Some of those aerial predators hunt flying insects by day, including some families of birds and all dragonflies, while bats do so at night. But all those predatory species are entertaining and inspiring to watch.
All these flying-insect predators are built for extensive, maneuverable flight. They are small, light in weight (birds even have bones filled with warm air), and have strong muscles to power their wings in rapid flight.
The small birds and bats have tiny legs that reduce the animals’ weight. Bats’ wings are made of skin stretched between long, thin fingers. Those fingers are also thin to reduce the bats’ weight.
A variety of birds — including flycatchers, such as eastern phoebes, eastern kingbirds, chimney swifts, and all species of swallows — catch insects in midair but in different ways and in a diversity of habitats.
Flycatchers perch on twigs and flutter out to snare an insect in the air, and then flit back to their perches to eat their victim and watch for more.
Swifts and swallows weave quickly among their fellows, without collision, to seine flying insects, one right after another, from the sky. Swifts generally careen higher in the sky than swallows do to catch prey, thus reducing competition between those two groups of birds for food.
As swallows and swifts retire for the night at twilight, little brown bats take wing from hiding in trees and swoop and dive across the darkening sky to catch flying insects in midair during dusk and into the night. The bats’ flight is erratic and swift as they track down each flying insect, one right after another.
Bats locate prey at night by emitting high-pitched squeaks that strike the insects and bounce back to the bats’ ears. Bats “see” their victims ahead by hearing the echoes bouncing off them. The bats’ minds can visualize how big and far away each object around them is.
Winged adult dragonflies, including green darners, white-tailed skimmers, and 12-spotted skimmers that are common in southeastern Pennsylvania, sweep over ponds, creeks, and dry land after flying insects to ingest.
These dragonfly species, and others, are intriguing to watch and help make the landscape more interesting in summer. And they are attractive to see in their color patterns and with four wings held stiffly out to the sides when perched on vegetation.
Dragonflies start life as camouflaged nymphs on the bottoms of still waters, where they prey on small invertebrates. But within a year, they become winged adults that leave the water and take to the air, where we see their beauties and intrigues.
Watch for these creatures catching insects in midair. They are very entertaining.
Clyde McMillan-Gamber is a retired Lancaster County Parks naturalist.