Last updated on October 23rd, 2023 at 09:06 pm
The dragonfly has existed on Earth for about 300 million years. In other words, it already existed in the era of the dinosaurs, the first mammals and the first birds. It is certainly the oldest insect.
Description of the dragonfly
The dragonfly is an odonate insect with a round head and two globular eyes with multiple facets. It has an elongated body equipped with four transparent wings with veins.
At rest, their wings do not fold back, which allows them to be classified in the order of paleoptera.
Their larvae undergo successive molts until the adult molt.
These larvae are aquatic, while the adults are terrestrial. The larvae breathe through their gills. Considered as a hemimetabolic insect, the metamorphosis of the dragonfly is incomplete.
What are the physical characteristics of the dragonfly?
The dragonfly has two pairs of transparent wings and three pairs of legs. It has a rigid external carapace and two short antennas. Its large eyes cover almost all its head.
The dragonfly is often presented under a black, green or blue color. It measures about 4 to 5 cm and weighs only a few grams. During its life cycle, the dragonfly metamorphoses. Its larva lives for several years before becoming a nymph. It then climbs on a stem and begins to breathe when it is ready to metamorphose into an adult.
The life expectancy of a dragonfly is quite short. Depending on the species, it ranges from a few days to a few months.
The behavior of the dragonfly
The flight of dragonflies is both precise and agile. During their egg-laying period, males often have a defensive and territorial behavior. When faced with direct threats, they may prey on large prey such as butterflies.
Dragonflies capture their prey with their two pairs of front legs and then tear them apart with their mandibles. If the prey is large, the dragonflies land directly on it to ingest it. Once they have consumed it, they wash themselves.
What is the life span of the dragonfly?
The life cycle of dragonflies consists of three phases: egg, larva and adult. When laying eggs, they can use several ways to deposit their eggs, namely:
A laying in flight on the surface of the water or in height;
By depositing on immersed plants or flush with the water;
By inserting the eggs inside the stem of certain aquatic plants;
By depositing eggs on plants around ponds.
Less than 1% of eggs develop into adults. During the larval phase, the larvae can moult up to 15 times during their cycle. The characteristics of the adult appear gradually at each of these stages.
What does the dragonfly eat?
According to scientists, the diet of dragonflies is similar to that of vertebrate predator species of odonates. Their favorite foods are mosquitoes, flies, horseflies and midges. For this reason, dragonflies are useful insects in the garden.
How to encourage the appearance of dragonflies?
It is easy to attract dragonflies when the garden is equipped with a pond. Indeed, they are particularly attracted by wetlands. However, it is preferable that the water feature in the garden does not contain fish.
On the other hand, the cultivation of emergent plants is recommended to ensure the laying of their eggs in spring. Water lilies and other reeds are also welcome to encourage the appearance of dragonflies. There are various plants such as yarrow, sage, subular sagittaria or echinacea that can attract them.