Dragonflies are not a bad species of insect to have in a yard -- they do no harm to humans, and their presence is a sign of a healthy ecosystem. They are beneficial in many ways, and some gardeners strive to attract the insects into their yard. Many species of dragonfly exist. Observing the insects through binoculars has become an enjoyable hobby for many in recent years.
Dragonflies (Anisoptera) belong to the insect order Odonata. They have large eyes that take up most of their head surface and a large body. They have four strong, broad wings, each capable of operating independently that enables dragonflies to be agile fliers. Individual dragonfly species are easy to distinguish by their field marks. Green darners, for instance, are identifiable by their green head and body. The four-spotted pennant dragonfly is easily recognized by its four dark spots, one on each transparent wing.
Dragonflies are drawn to areas where there is standing water, such as ponds, streams and wetlands. They are often found in moist meadows with lots of flowers. If you have a pond or stream near your land, or if recent rains have left flooded areas, this may draw dragonflies to your yard. They breed in water and feed on insects found near water, such as mosquitoes. Homeowners interested in attracting dragonflies often install small ponds in their yards for this purpose.
If you normally have a few dragonflies in your yard, but suddenly find you have swarms of them, it may be due to weather conditions, which sometimes collude to create an ideal environment for the insects to thrive. Summer 2010, for instance, was a record year for dragonflies in Wisconsin and other areas due to a combination of an early, deep snowfall before the wetlands froze the previous winter; an early, warm spring, which produced abundant food for the insects; and a hot and wet summer, which created perfect breeding conditions for the dragonflies.
Dragonflies serve as natural insecticides of troublesome insects, particularly mosquitoes. Adult dragonflies feed on mosquitoes and also flies, both which serve as staples in their diet. In addition, dragonfly larvae, which hatch beneath water and remain underwater all summer long as aquatic invertebrates, feed on quantities of mosquito larvae, thus contributing to the elimination of mosquitoes in your yard.