What are facts about dragonflies please do not talk about them being related to dragons?

Dragonflies have been around 300 million years. One prehistoric fossil had a wingspan of 2 1/2 feet! Today, the largest dragonfly is found in Costa Rica. It has a wingspan of 7 1/2 inches. * Dragonfly eyes contain up to 30,000 individual lenses. Human eyes only have one. * They have two sets of wings. They don't have to beat their wings in unison like other insects do. Their front wings can be going up while their backs ones are going down. * They only flap their wings at about 30 beats per second (bps) compared to a bee's 300 bps. * Excellent and strong fliers, they can loop-the-loop, hover, and fly backwards. * An Australian variety has been clocked at 36 miles per hour. * Dragonfly nymphs (the first stage after hatching) live in the water for about a year. * While underwater they eat mosquito nymphs, tiny fish, and pollywogs. When they have matured to airborne insects, they catch mosquitoes and gnats in mid-air before devouring them. * After leaving the water and becoming flying insects, they only live for about a month. * Their natural predators are birds.