Monochamus alternatus - Pine spotted longhorn beetle

It is an insect belonging to the family Cerambycidae in the order Coleoptera of the class Insecta. It is a pest of pine trees, and is found from Honshu to the Ryukyu Islands, and is also distributed in the Korean Peninsula, Taiwan, and China. It is 18 to 30 mm long, and its body is dark brown or blackish brown, but is covered with yellowish brown or reddish rust-colored hairs, with a pair of reddish rust-colored vertical stripes on the pronotum and three vertical stripes of the same color on each side, and the space between them has alternating white and black hair spots. Its antennae are reddish brown, and are more than twice the body length in males, and nearly one and a half times the body length in females. Adults appear from May to September, are active at night, and bite young pine branches and lay eggs on dead branches. This insect carries the pine wood nematode in its body, and since it invades pine trees when it bites, it causes pine wilt disease, and control is a problem. For this reason, aerial spraying of Sumithion has been carried out for some time, but it is known to be only moderately effective and to have a greater impact on other small animals. It has been reported that placing bait to attract and capture the reptiles is far more effective.

[Takehiko Nakane]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

昆虫綱甲虫目カミキリムシ科に属する昆虫。マツ類の害虫で、本州から琉球(りゅうきゅう)諸島まで産し、朝鮮半島、台湾、中国にも分布する。体長18～30ミリ、体は暗褐色ないし黒褐色であるが、黄褐または赤銹(あかさび)色の毛に覆われ、前胸背部に赤銹色の縦条が一対あり、上ばねは各三条の同色の縦条があって、その間室は白と黒の毛斑(もうはん)を交互にもつ。触角は赤褐色で雄では体長の2倍以上、雌でも1倍半近くある。成虫は5～9月に現れ、夜間活動してマツの若い枝を噛(か)み、枯れた枝に産卵する。この昆虫は体内にマツノザイセンチュウを保有しており、噛食(ごうじき)の際にマツに侵入するので松枯れの原因となるため、防除が問題になっている。そのためスミチオンの空中散布が以前から行われているが、効果は薄く、ほかの小動物に影響が大きいことが知られており、餌木(えぼく)を置いて誘引し、捕獲するほうがはるかに効果的であるとの報告がある。

［中根猛彦］

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