The reason why dragonflies fly so low sometimes
The time when the dragonfly flies very low is when it is about to rain. Before it rained, there was a lot of water vapor in the air, and the worm’s wings were wet with water vapor, so the worm did not fly high at this time. The dragonfly wants to catch the bug and eat it, so it has to fly low. Therefore, when the children see the dragonfly flying low, they know that it is about to rain, and then they have to go home quickly.
The difference between the humidity of the air before rain and the humidity in a sunny day is not very different. Moreover, it does not mean that the humidity in the air before rain must be greater than the humidity in a sunny day. Sometimes the humidity in the air is also very high in a sunny day. , And caused extreme sultry heat, but at this time the dragonfly in the sky did not fly very low. This shows that. The influence of humidity in the air on the ability of insects to fly is not as great as people imagine.
The evolution of nature has made the wings of most insects have their own waterproof measures. These waterproof measures have a high degree of reliability and practicality, so that the wings of insects generally do not stick to fog, and they are less likely to be affected by humid air. wet. Insects must have the ability to maintain the ability to fly in various humidity climates to ensure their survival in the cruel natural environment. Just imagine, if the flight ability of that kind of insects is greatly affected in humid air, they must It will be swept away by its own natural enemies and will never survive today. Therefore, there should be other reasons for insects to lower their flying height in cloudy days.
In the process of biological evolution, it must be reasonable for a biological to have a certain instinct, otherwise there is no need to evolve this instinct. The choice of biological evolution is often the most scientific choice. The author believes that insects choose to lower their flying height when it is cloudy to prevent damage from lightning, rain and hail.
Usually before it rains, the humidity in the air is quite high, and when the dragonfly is flying, when it encounters damp moisture, it often wets its wings; this is a good time for the dragonfly to catch prey, so it will be seen Dragonflies fly low. Even though the dragonfly’s ability to fly is stronger, because the wet body is heavier, it is difficult to fly at higher places as usual, but can only fly at low altitude. This phenomenon can only show that the air pressure is low. Sometimes it doesn’t rain.
Before it rains, the humidity is high, and the damp moisture will wet the wings;
This is a good time for dragonflies to catch prey, so dragonflies fly low. This phenomenon can only show that the air pressure is low, and sometimes flying low without rain is the practice of insects preyed by dragonflies to protect themselves before rain.
Insects are not unable to fly high in humid air, but in order to prevent rain, hail and lightning from harming themselves, they instinctively lower their flying height before it rains. Those who can’t fly as soon as they encounter humid air Insects, even if they have appeared in history, are now eliminated by nature. In fact, the real flying masters on earth are all kinds of flying insects, not humans. Humans are not qualified to question the ability of insects to fly in humid air.
Most of the members of this order Odonata are large and medium-sized insects with large heads and flexible rotation. Two pairs of wings are transparent and membranous. The wings have multiple transverse veins. There are often wing moles on the front edge of the wing near the top of the wing. It is distributed throughout the world, especially in tropical regions. Many. About 5,000 species are known, and about 350 species and subspecies are recorded in China. Many dragonflies do not have ovipositors. They hover over ponds, or fly back and forth along streams, and drop their eggs in the water during flight; some species are close When flying on the surface of the water, use the tail to “point the water” and lay eggs into the water. Adults catch insects of appropriate size for food during flight.
Insects of the dragon family fly over open ground. Insects of the family Pyrididae often come out at dusk to prey on mosquitoes, small moths, leafhoppers, etc., and are important beneficial insects. When the weather turns bad, insects mostly fly on the ground. It can show that the air pressure is low, and sometimes it does not rain.
The appearance characteristics of dragonflies
Dragonflies can be divided into Hyphenoptera of Dragonflies and Homoptera (Rapidoptera) of Damselflies. There are only three types of dragonflies in Meoptera, Japan, India and China. This suborder is called living fossil. , China’s oldest. It is also a very primitive insect in the Pterygota. The larvae are called larvae, which are completely aquatic, and their morphology and habits are completely different from those of adults. The morphology of various larvae vary greatly.
The dragonfly is the insect with the most eyes in the world. The dragonfly’s eyes are large and bulging, occupying most of the head. There are three monocular eyes. The compound eye is composed of more than 28,000 small eyes. They have excellent eyesight and can look up, down, forward, and backward. Without turning your head. In addition, their compound eyes can measure speed. When an object moves in front of the compound eye, each “small eye” reacts in turn, and the speed of the target object can be determined after processing. This makes them master insect catchers in the insect kingdom. Its chewing mouthparts are developed, powerful and powerful.
Dragonfly has well-developed wings, the front and rear wings are equal in length and narrow, membranous, and the veins are extremely clear. The flight ability is very strong, up to 10 meters per second. It can both suddenly turn back into the sky, and sometimes fly back. When resting, both wings spread out on both sides, or stand upright on the back. The front wings and hind wings are not similar, the hind wings are often larger than the front wings. There is a wing mole on the front edge of the wing and near the top of the wing, each of which is rectangular or square, which can maintain the regularity of the vibration of the wing and prevent breakage caused by tremor. The chest is slanted, and the front chest is small and can move. The feet are close to the head (to facilitate predation). The abdomen is slender. Although the structure of the adults is quite the same, the size is very different, and the wingspan is generally 5 cm. From the smallest 1.8 cm (0.7 inches) to the largest 19.3 cm (7.5 inches).
Dragonfly abdomen is slender, flat or cylindrical, with anal appendages at the end. The feet are thin and weak, with barbs, which can catch pests when flying in the air. The male mating organ is located on the second and third abdominal abdomen. Male and female mating also takes place in the air. When flying on the surface of the water, most females “spot” their eggs in the water several times, and some insert their abdomen into shallow water to lay their eggs on the bottom.
Dragonflies are incompletely metamorphic insects. The larvae “Shuiji” live in water, breathe in the water with the gills of the rectum and trachea, and prey with a well-developed face cover. Generally, it takes more than 11 times to molt, and it takes 2 or more years. Climb out of the water along the water weeds, and finally shed their skins and emerge as adults. The larvae can prey on larvae or other small animals in the water, and sometimes the same kind also cannibalize each other. Both adults and larvae are carnivorous and eat more pests. In addition to predating large amounts of mosquitoes and flies, adults can also prey on pests such as butterflies, moths, and bees, which are actually beneficial insects. Like to fly back and forth at low altitude before it rains.