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Horticulture and Home Pest News
Horticulture & Home Pest News is filled with articles on current horticulture, plant care, pest management, and common household pests written by Iowa State University Extension specialists in the Departments of Entomology, Horticulture and Plant Pathology.

Dragonflies Put On An Aerial Display

This article was published originally on 8/26/2009

Two years ago we wrote about the exciting phenomena of seeing swarms of dragonflies on a muggy, late summer evening. Several calls and messages over the past few days indicate others are getting to enjoy the spectacle this year. It's a special moment when you first realize what's happening; hundreds of dragonflies are darting and zigging and zagging above your lawn or just above the crop in the field. Since it usually happens at sunset, the low light reflects and sparkles off their cellophane-like wings.
 
Dragonflies, of course, are those long, slender-bodied, familiar insects commonly seen skimming over the water of a lake, stream or pond. Body colors range from green to brown to shiny silver depending on species. Dragonflies do no harm people, pets, crops, landscape plants or houses. They are entirely beneficial, first as a vital part of the aquatic food chain, and second as predators of mosquitoes and other insects. 
 
Dragonflies are aggressive predators. As they fly back and forth over the water or landscape they are sweeping mosquitoes, gnats, winged ants and other small insects from the air using their spiny front legs that are held like a basket just under the mouth.
 
In the fall and at dusk, the insects they are probably eating the most of are winged ants. Winged ants, also called swarmers, are emissaries produced by a successful, well-established colony. The winged adults are sexually developed males and females that depart from the colony in an attempt to perpetuate the species by establishing a new colony somewhere else. They have very, very slim chances of success. Most will die of starvation, dehydration or will be eaten by birds, dragonflies or other predators. Though almost all will fail, just enough succeed to spread the species and ensure its survival.
 
Winged ants are harmless. They do not create mounds in your lawn, dirt piles on your driveway or sawdust at the base of your hollow tree. Swarming is a temporary, natural event and is not a permanent or major problem. Besides, as mentioned, swarmers are beneficial as an important link in the ecosystem food chain. Outdoors, ignore them if possible.
 
As for the dragonflies, live and let live. Sit back and enjoy the show.


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