dragonfly life cycle

Life Cycle

Eggs are laid
and larvae
hatch

Dragonflies are large insects belonging to the insect order Odonata. They have three main body parts: a head, a thorax to which the legs attach and an elongate abdomen. Their life cycle includes an aquatic larval phase and an adult terrestrial phase. As adults they may spend considerable time away from water as they forage for insects.

Eggs are laid in or near water. For species that lay their eggs near water, development will not begin until the rains come and the water level rises. If the temperature is appropriate, larvae will hatch from the eggs in less than a month.

Feeding

Dragonfly larvae form an important link in aquatic food webs. The larva or nymph will grow rapidly feeding on small aquatic organisms. Some nymphs sit and wait for prey items, but others are active stalkers. Nymphs have a specialized lip that can be rapidly extended up to 1/3 the length of the body to help them capture prey. As the nymphs grow they will switch to hunting larger insects, including mosquito larvae. Large nymphs can capture small tadpoles and fish. Nymphs will molt or shed their skin 10 to 15 times before they are mature.

Nymphs breathe through gills located inside the posterior end of the digestive tract. These can extract oxygen from the water. Water forced from the chamber housing the gills can be used like a jet to propel the animal through the water.

Emergence

Depending on the species it can take several weeks to five years for the nymphs to mature. As the nymphs mature the wing pads elongate and adult colors become visible through the skin (photo on left). They will move to the surface of the pond and start to breathe air . Often in the evening, nymphs climb up the stems of emergent vegetation. They swallow air causing their skin to split down the back. Gradually the adult emerges. The wings will slowly unfold as blood is pumped into them. Recently emerged adults are soft and excellent prey. It will take many hours before the wings harden and the dragonfly is ready for flight. If you go to the pond in the morning and look on the stems of plants the exuviae or skins can be found (photo on right). These provide a good clue to the types of larvae in the pond. The exuviae shown probably belongs to the Common Green Darner.

Mating

The first step in mating occurs when the male grasps the female with his legs. He then clasps her behind the head with specialized appendages at the end of his abdomen. This head to tail position is called the tandem position. Near ponds dragonfly pairs can often be seen cruising in this position. The next step occurs when the female folds her abdomen under the male and removes a sperm packet. This circular mating position is call the wheel position. In some species the wheel position can be initiated while they are in flight but in others like these meadowhawks the pair perches.

Life Cycle Eggs are laid and larvae hatch		Dragonflies are large insects belonging to the insect order Odonata. They have three main body parts: a head, a thorax to which the legs attach and an elongate abdomen. Their life cycle includes an aquatic larval phase and an adult terrestrial phase. As adults they may spend considerable time away from water as they forage for insects. Eggs are laid in or near water. For species that lay their eggs near water, development will not begin until the rains come and the water level rises. If the temperature is appropriate, larvae will hatch from the eggs in less than a month.
Feeding		Dragonfly larvae form an important link in aquatic food webs. The larva or nymph will grow rapidly feeding on small aquatic organisms. Some nymphs sit and wait for prey items, but others are active stalkers. Nymphs have a specialized lip that can be rapidly extended up to 1/3 the length of the body to help them capture prey. As the nymphs grow they will switch to hunting larger insects, including mosquito larvae. Large nymphs can capture small tadpoles and fish. Nymphs will molt or shed their skin 10 to 15 times before they are mature. Nymphs breathe through gills located inside the posterior end of the digestive tract. These can extract oxygen from the water. Water forced from the chamber housing the gills can be used like a jet to propel the animal through the water.
Emergence		Depending on the species it can take several weeks to five years for the nymphs to mature. As the nymphs mature the wing pads elongate and adult colors become visible through the skin (photo on left). They will move to the surface of the pond and start to breathe air . Often in the evening, nymphs climb up the stems of emergent vegetation. They swallow air causing their skin to split down the back. Gradually the adult emerges. The wings will slowly unfold as blood is pumped into them. Recently emerged adults are soft and excellent prey. It will take many hours before the wings harden and the dragonfly is ready for flight. If you go to the pond in the morning and look on the stems of plants the exuviae or skins can be found (photo on right). These provide a good clue to the types of larvae in the pond. The exuviae shown probably belongs to the Common Green Darner.
Mating		The first step in mating occurs when the male grasps the female with his legs. He then clasps her behind the head with specialized appendages at the end of his abdomen. This head to tail position is called the tandem position. Near ponds dragonfly pairs can often be seen cruising in this position. The next step occurs when the female folds her abdomen under the male and removes a sperm packet. This circular mating position is call the wheel position. In some species the wheel position can be initiated while they are in flight but in others like these meadowhawks the pair perches.