Sanae dragonfly - Sanae dragonfly

A general term for insects belonging to the family Gomphidae in the order Odonata of the class Insecta. All species have black and yellow markings on their bodies. Some larvae grow in stagnant water (such as the Japanese dragonfly and the fan-tailed dragonfly), but most grow in the gravel or mud at the bottom of running water. Many emerge in the spring, and adults feed on trees for 2-3 weeks after emerging, flying to water once their bodies have matured. The female's ovipositor is simplified to a valve-like shape, and eggs are scattered in water or damp soil. The larval stage lasts 3-5 years. This family is distributed widely around the world, but there is only one species in the New Guinea region. Large species found in Japan include the fan-winged dragonfly and the small-winged dragonfly, while medium-sized species include the mountain dragonfly, the mountain dragonfly, the long-tailed dragonfly, the blue dragonfly, the spectacled dragonfly, and the true dragonfly, while small species include the small dragonfly, the dark-spotted dragonfly, the small black dragonfly, and the white-tailed dragonfly. Most emerge in the spring, but those that appear in the summer include the spectacled dragonfly, the Nagoya dragonfly, the giant dragonfly, the fan-winged dragonfly, the Taiwan fan-winged dragonfly, and the mountain dragonfly, and of these, the four species except for the last two species live in lakes and large rivers with muddy bottoms.

[Shojiro Asahina]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

昆虫綱トンボ目サナエトンボ科Gomphidaeに属する昆虫の総称。いずれも体に黒色と黄色の斑紋(はんもん)をもつ種類である。幼虫は停水に育つものも若干あるが（コサナエ、ウチワヤンマなど）、大部分は流水の水底の砂礫(されき)や泥土の中で育つ。春季に羽化するものが多く、成虫は羽化後2、3週間は樹上にいて摂食活動をし、体が成熟してから水域に飛来する。雌の産卵器は弁状に単純化し、卵は水中や湿土中に散布される。幼虫期間は3～5年を要する。この科は世界に広く分布するが、ニューギニア島地域にはわずか1種あるにすぎない。日本産の大形種にはウチワヤンマ、コオニヤンマがあり、中形種にはヤマサナエ、ミヤマサナエ、オナガサナエ、アオサナエ、メガネサナエ、ホンサナエなどがあり、小形種にはコサナエ、ダビトサナエ、ヒメクロサナエ、オジロサナエなどがある。大部分は春季に羽化出現するが、夏季に現れるものにメガネサナエ、ナゴヤサナエ、オオサカサナエ、ウチワヤンマ、タイワンウチワヤンマ、ミヤマサナエがあり、このうち最後の2種を除いた4種は泥底の湖水や大河の生息者である。

［朝比奈正二郎］

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