Protecting the Cherry Trees of Mount Yoshino from the Invasive Red-Necked Longhorn Beetle
When it comes to cherry blossoms, it is no exaggeration to say that they are the flowers that Japanese people look forward to blooming the most🌸
Are you aware of the existence of an insect called the
Red-Necked Longhorn Beetle that threatens these cherry trees?
Currently, damage is occurring at famous cherry blossom spots where trees are dying due to this insect.
I recently learned about the Red-Necked Longhorn Beetle and control measures at Mount Yoshino, a famous cherry blossom spot in Kansai,
so I would like to summarize the information in this article.
If you already know about the Red-Necked Longhorn Beetle,
or if you don't know but want to do anything you can for the sake of the cherry trees,
you can jump to the [Spread the Word] section from the table of contents below🙌
It is characterized by a glossy black body overall with a red thorax (the neck area).
The body length is 2.5 to 4 cm (excluding the antennae).
Originally distributed in China, the Korean Peninsula, etc.,
it is thought to have entered Japan accompanying imported cargo and wooden packaging materials.
It was first confirmed in 2012.
Since then, it has expanded its distribution,
and is currently confirmed in 13 prefectures.
What is the problem with this insect?
Adult Red-Necked Longhorn Beetles emerge from late May to August.
After mating immediately, they fly around
and lay eggs in the cracks of trunks and main branches.
The number of eggs is very large, averaging 350,
with some individuals laying over 1,000.
The hatched larvae enter the inside of the tree
and grow inside the tree over 2 to 3 years.
Trees infested by larvaehave their
insides eaten away, causing them to
weaken and eventually die.
The damage affects Rosaceae tree species,
such as cherry, plum, peach, and apricot trees...
Damage is occurring in street trees and orchards.
Because the Red-Necked Longhorn Beetle moves by hiding in packaging materials,
just as it entered the country,
you cannot let your guard down even if you are not adjacent to a damaged area.
What invasive species have in common is
that they have stronger reproductive power than native species
and continue to live even in harsh conditions...
As I have written so far,
the damage from the Red-Necked Longhorn Beetle also extends to fruit trees such as plum and peach.
Despite having cherry blossoms in the title,
I apologize for writing this article...
but after receiving a request to share and spread the word
about the current situation from the organizer of an activity I recently joined,
I wanted to do my small part to help,
so I am writing this article🙏
Below, I will write about the activities and the request for support,
and I apologize for my poor writing, but please read it.
Participating in the activities of the Yoshinoyama Hoshokai
On Saturday the 13th, in Yoshino Town, Nara Prefecture,
I joined the Yoshinoyama Hoshokai, which preserves the cherry blossoms,
to carry out red-necked longhorn beetle control measures🙌
There was a large group of 80 participants
gathered from Nara Prefecture, the Ministry of the Environment, companies, and more✨
The reason I participated in this activity is that
I learned about the damage caused by the red-necked longhorn beetle somewhere,
and when I was thinking that I would like to help if I had the chance,
I found out about this activity🍂
I had visited Yoshino Town before,
and although it was only once, I was moved by the cherry blossoms of Yoshino...
I participated with the sole desire to protect those cherry blossoms🌸
The cherry blossoms of Mount Yoshinooriginate from the fact that the founder of Shugendo,|En no Gyojacarved the figure ofKongo Zao Gongen, which he perceived during his ascetic training, into a cherry tree and enshrined it.Those cherry trees became objects of worship as sacred trees, and because they were planted and passed down by believers, they became one of Japan's leading cherry blossom spots. A key feature is that they were planted not for flower viewing, but asproof of faith,making them an important part of the World Heritage site 'Sacred Sites and Pilgrimage Routes in the Kii Mountain Range'.
In Nara Prefecture, the damage was first discovered in 2019.
Since then, the damage has spread, mainly in the northwest,
and in October 2025, damaged trees were discovered for the first time on Mount Yoshino
(the first confirmation in a national park in Japan).
If the damage is left unchecked, they will become adults
and lay eggs on surrounding cherry trees again,
creating a vicious cycle,and trees that become severely damaged
will have no choice but to be cut down😢
If things continue like this,
the magnificent cherry blossom landscape of Mount Yoshino,
known as the 'Hitome Senbon' (a thousand trees at a glance), could be lost...
The countermeasure being taken for this
is the control treatment we practiced in this activity.
No special skills are required, but...
Before starting, we were instructed on the control methods,
and we worked in groups of about four people.
There are several ways to control the red-necked longhorn beetle,
but this time, among thechemical controlmethods (chemical pesticides), we used
a method of injecting chemicals from the trunk to distribute the pesticide throughout the interior of the tree
to kill the larvae in contact with it,
using a trunk injection agent.
There seem to be various injection agents,
but we used 'Revive' for the activity.
《Step 1》
Measure the circumference with a special tape measure.
The diameter was 46 cm and the trunk circumference was 145 cm,
so we knew that 13 trunk injection agents were needed.
(drilling at intervals of about 11 cm)
《Step 2》
As close to the base as possible,
drill a hole about 5 cm deep into the trunk at a 45-degree angle
along the vascular bundles where the chemical will rise.
《Step 3》
Insert the injection agent into the drilled hole.
For this tree, 12 more to go
Repeat the same process and the injection is complete
It seems it takes from several hours to a day
for the chemical to penetrate the tree,
and post-treatment is required after penetration is confirmed
Insert a paste-like wound healing agent into the hole,
apply a cut-sealing agent to the surface, and it's done
You only use tools when drilling the holes,
so no special skills or experience are needed, but
it requires over 10 operations per tree,
and even with several people splitting the work, it took time💨
Cherry trees are often on steep slopes,
so the unstable footing makes it a laborious task💦
However, more serious than the time and effort
is the lack of funds needed for control measures...
For control measures like chemical injection,
about 15,000 to 30,000 yen is needed per cherry tree.
Since there are about 30,000 cherry trees on Mount Yoshino,
if you do the math...😱
Even if they can't treat all the cherry trees at once,
they want to treat about 500 trees
before the adult Red-Necked Longhorn Beetles fly in the summer
[Please Share] Mount Yoshino Crowdfunding
From December 1, 2025, to January 31, 2026,
they are conducting crowdfunding
to raise funds for control measures
About 1/4 of the period has passed,
and the achievement rate is at 18%, which is a bit sluggish...
The damage from the Red-Necked Longhorn Beetle isn't just to cherry trees,
and the damage to cherry trees isn't limited to Mount Yoshino,
and since I'm a newcomer, I can't speak too boldly, but
I've only visited a few times,
but Yoshino is a special place to me,
and rather than just wanting to protect the cherry blossom scenery of Mount Yoshino,
I don't want to lose the charm of Yoshino,
so I decided to do what I can🫡
This article is one of those things
Even just letting people know about the threat of the Red-Necked Longhorn Beetle and that the cherry blossoms are in crisis
I think it will be a trigger for people to think
that the cherry blossoms blooming every year are not something to be taken for granted
Personally, I can be satisfied that just that alone
makes writing this worthwhile, but
the reality is that you can't do anything with just feelings alone...
If it's difficult to provide actual work support,
I think the best thing to do is at least support with funds,
I personally will definitely support the crowdfunding,
and I plan to participate in the control work if there is a call for volunteers.
So... it's not just because of that, but
Mount Yoshino Crowdfunding
it requires member registration and takes some effort, but
I would appreciate it if you could consider supporting it 🥹
Anything you can do is fine, so
spreading the word on social media, etc.would also be appreciated 🙏
You can share the article itself or just the crowdfunding page,
either is fine 🙇
(Referenced page)
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