When it rains, because the air pressure is relatively low, insects living in caves will come out to move. At this time, animals such as swallows and dragonflies will be attracted, because they can catch these insects as food. Houses, beams and other places are places where insects like to live, which will attract dragonflies.
Introduction:
Dragonfly (scientific name: dragonfly), alias Dengdianer, Leech, Odonata, Odonata, beneficial insect. Common dragonflies such as blue dragonflies are distributed in Zhejiang, Sichuan, Guizhou and other provinces, green dragonflies with moles are distributed in North China, and jade dragonflies are only distributed in Beijing, Jiangsu and Fujian.
Dragonflies are generally large in size, with long and narrow wings, three eyes, 1 pair of antennae, thin and short, chewing mouthparts, slender, flat or cylindrical abdomen, anal appendages at the end, thin and weak feet and barbs. Larvae (larva) develops in water and breathes through rectum, trachea and gills in water. Generally, it takes more than 1 1 times to molt, and it takes more than 2 years to climb out of the water along the aquatic plants, and finally molt and emerge as adults.
Species of Dragonflies in China: Needham (1930- 1932) recorded 283 species of Odonata in China in China Dragonfly Manual and its subsequent supplements. Hu Jingfu (1935) recorded 308 species of China Odonata in the Catalogue of Dragonflies in China.
Sui Jingzhi and Sun (1986) recorded 208 species of dragonflies in China according to the China dragonfly specimens collected by the Institute of Zoology, Chinese Academy of Sciences at that time.
Davies et al. (1984- 1985)' s World Dragonfly Directory is considered to be the most complete dragonfly directory in the world today, and * * * contains more than 5,600 known dragonflies in the world. Only more than 250 species are known in China. Zhao Xiufu (1990) recorded 22 genera 145 species of Bombycidae in China.