Hawthorn spider mite

A mite belonging to the Arthropoda phylum, Arachnida class, Acarina order, Tetranychidae family. It is well known as a pest of fruit trees, and the end of the peritreme located at the front of the body is swollen like a fist. The body length of the female is about 0.5 mm, and that of the male is about 0.4 mm. The eggs are orange-yellow. It is distributed in Europe and Asia (Japan and southern Korea), and parasitizes on plants of the Rosaceae family such as hawthorn, apple, pear, cherry, and Japanese quince, and deciduous broad-leaved trees such as Quercus crispula. In northern Japan, there are about 4 to 6 generations per year. It parasitizes by stretching threads between the veins on the underside of the leaves. The affected areas fade and become mottled, and the entire leaf gradually turns brown. It also parasitizes fruit. Summer-type females are red. Dormant females are bright red and hibernate by gathering under the bark or in cracks on trunks and branches.

[Mori Fansu]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

節足動物門クモ形綱ダニ目ハダニ科に属するダニ。果樹害虫として有名なダニで、体の前部に位置する周気管peritremeの末端はこぶし状に膨れている。体長は雌0.5ミリメートル内外、雄0.4ミリメートル内外。卵は橙黄(とうこう)色。ヨーロッパ、アジア（日本、朝鮮南部）に分布し、サンザシ、リンゴ、ナシ、オウトウ、ボケなどのバラ科植物およびミズナラなど落葉性広葉樹に寄生する。年間の世代数は北日本では4～6回ぐらい。葉の裏面の葉脈の間に糸を張って寄生している。被害部は退色し斑紋(はんもん)となり、しだいに葉全体が褐色に変わる。果実にも寄生する。夏型雌は赤色。休眠雌は鮮紅色で幹や枝の樹皮下や割れ目に集合して越冬する。

［森　樊須］

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