It has been stated by environmental scientists that Dragon Flies in the garden are an indicator of a healthy well balanced environment in addition their sensitivity to habitat quality and their amphibious life cycle make dragonflies well suited for evaluating environmental changes.
Machado’s Skimmer Orthetrum machadoi (female) taken in my garden at Mount Moreland
They are carnivorous not only in the adult stages of their life cycle, but also in their larval stage. The dragonfly is considered as one of the best agile predator around.
During their nymph phase, when a dragonfly has to remain underwater, it eats aquatic insects, worms, mosquito larva, small fish, and little tadpoles. In this phase, it is empowered with a thrust mechanism system to boost its speed while following its prey. It also ejects water from its anal opening to increase its speed in times of need.
They feed on small insects such as bees, ants, wasps, butterflies, flies, and midges. A dragonfly has the ability to move in different directions swiftly. Hence, it can easily out-fly its prey on most occasions
Adult dragonflies often hunt for food in groups, when ants or termites are available in large numbers or when there are swarms of gnats are available in their proximity. Dragonflies keep mosquitoes at bay by feeding on them.
Julia Skimmer Orthetrum Julia (male) taken in my garden at Mount Moreland
It is rather easy to attract these most interesting and attractive insects into a healthy indigenous garden by providing breeding opportunities for them in the form of a natural pond either large or small in fact a tub with a few local aquatic plants is all that it takes to provide a breeding opportunity for dragonflies just as long as no fish are placed in them. There is no need to worry about mosquitoes once the pond had matured and attracted dragon flies as their larvae are voracious carnivores which relishing mosquito larvae.
For biological control to work enough mosquito larvae must survive in the ponds to feed the dragon fly nymphs, which largely feed on mosquito larvae, so a few larvae will always be found in the ponds, however this small number is compensated for a thousand fold by the vast numbers of adult mosquitoes that arrive from other sources that are controlled by the adult dragon flies.
In my own garden I have a number of tubs and shallow containers planted to an assortment of aquatic plants that together with plantings of suitable flowering plants attract very large numbers of Dragonflies to my own garden which act as a very good control for both flies and mosquitos.
To help enhance the garden to attract dragonflies the addition of plants like Anthericum saundersiae, Chlorophytum cooperii and flowering grasses which attract large numbers of suitable insect pollinator provide vast amounts of food for these aerial acrobats.