The trees in a Japanese garden, eaten down to bare sticks
A friend has an old house in the countryside of Kyushu, Japan. A few days ago he sent me a photo: the row of hedge in the yard had been chewed down to bare branches, and from outside you could see the wall of the house directly. He looked it up and said it had been eaten away by the larvae of a moth called «キオビエダシャク».
What kind of insect this is
キオビエダシャク (the Japanese name; Chinese sources sometimes render it as «yellow-banded looper» (translations not yet standardized), and the formal name in the entomological record is the one to go by): the larva is a looper about 5 cm long, with an orange head and tail-end and grey-black markings on the body; the adult, after emerging, has a wingspan of about 5 cm, a dark blue ground with a yellow cross-band. It feeds specifically on trees such as the inumaki (イヌマキ) — in Japan the inumaki is an extremely common hedge and garden tree.
The trouble lies in how it eats: the larvae strip the leaves completely, and the tree then dies. Local authorities such as Saiki City in Oita Prefecture and Kagoshima City have issued dedicated control notices, explaining that when there are few larvae you can shake the tree and kill the ones that drop off, and when there are many you use a spray; the adults fly about, so chemicals have limited effect, which makes the larval stage the critical window. The local notices also mention that this kind of damage has been spreading since last year.
Why Japanese people care so much about the trees in the yard
In the yards of Japanese homes, the 生垣 (ikegaki, the clipped hedge) made of evergreens such as inumaki, camellia and maple is both a partition and a facade. It has to be green all year round; once insects have eaten it down to bare sticks, it is as though a whole wall has fallen in — which is why the tone of the local government notices is more urgent than for an ordinary pest problem.
When to act matters more than what to act with
The local government notices are very specific: the adults fly around, chemicals have limited effect and catching them is hard, so the genuinely effective window is the larval stage — when there are few, shake the tree and stamp on the ones that fall to the ground; when there are many, spray according to the instructions, and after spraying keep an eye on the rain. In other words, by the time the yard looks «bald», it is usually a season too late.
It comes to the same thing as what people who grow trees often say: problems with trees arrive slowly, and the timing of the intervention matters more than the method.
Trees in a Chinese yard have their own rules
The most widely repeated Chinese folk saying about what to plant in a yard is «no mulberry in front, no willow behind, no ghost-clapping hands in the middle of the yard»: don't plant mulberry in front of the house, because «mulberry» (桑) sounds like «mourning» (丧); don't plant willow behind the house, because «willow» (柳) is homophonous with «flow away» (流), and there is a worry that wealth will flow out; and the «ghost-clapping hands» refers to the poplar — its leaves are large, and when the wind blows the rustling is loud, sounding at night like someone clapping.
Interestingly, each of these taboos hides a practical reason. Poplars grow fast and their wood is not particularly strong, and accidents in which a branch is snapped off by wind and hits the house are not rare, so planting one in the middle of a yard really is unsettling; there is also a folk saying that «the willow bears no seed», and in an era that valued carrying on the family line, that made the willow still less welcome; mulberries attract insects easily and drop a lot of leaves, so planting one in front of the house really is a nuisance. The taboo is the packaging; inside it is usually experience.
One thing to be clear about: there is no causal relationship between a tree thriving or withering and the fortunes of the household. What folk custom offers is a set of sayings for «keeping the home in order», giving people grounds for a decision — replace the tree that should be replaced, prune the branch that should be pruned, and no more.
How my friend dealt with it
He did not cut the trees down. He sprayed first, then replaced the two by the wall with varieties this insect does not attack. He said the advice the old people in the countryside gave was simpler: «The tree is your own; when the leaves turn yellow you have to deal with it, don't wait until only the trunk is left.»
If you too have been going round and round on something that looks unsolvable lately, you might first write its threads down one by one. When it is over and you look back at them, you can often see what was really making things hard for you at the time.
This article's information is current as of 15 September 2026; for control information, the latest notices from the local agriculture and forestry authorities take precedence.
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Sources
- Saiki City, Oita Prefecture, 〈イヌマキ等の害虫（キオビエダシャク）被害にご注意ください。〉 (appearance, damage and control methods): https://www.city.saiki.oita.jp/kiji00310814/index.html (accessed 15 September 2026)
- Kagoshima City, 〈イヌマキの害虫「キオビエダシャク」に注意〉 (local government control notice): https://www.city.kagoshima.lg.jp/seisanryutu/sangyo/norin/oshirase/kiobiedashaku.html (accessed 15 September 2026)
- Beijing Municipal People's Government, 〈四合院种树不止谐音梗那么简单〉 (Li Weiwei; where the saying «no mulberry in front, no willow behind, no ghost-clapping hands in the courtyard» comes from and what it means): https://www.beijing.gov.cn/renwen/sy/bq/qsbj/zlzz/lww/202008/t20200821_1988425.html (accessed 15 September 2026)
- The agriculture knowledge portal of the Taiwan region's agriculture authority, 〈為什麼古人說：前不栽桑，後不植柳?〉 (folk sayings such as that the «ghost-clapping hands» means the rustling-leaved poplar): https://kmweb.moa.gov.tw/knowledge_view.php?id=1452 (accessed 15 September 2026)