Samrak Ecological Park in Sasang-gu, Busan is a vast riverside park spreading to the left and right of the Nakdong River. It has an area of ​​4722,000 square meters and is well-equipped with sports facilities, lawn squares, and a natural learning area. Since it was created along the riverside, it is a well-established'willow tree' colony that loves streams. It grows to about 20m and creates a cool shade in summer. By the way, the willow trees in Samrak Ecological Park have been dying from the attack of the'Sky Cow', which was once dearly treated. What happened?

Willow has a lot of water and it has a very hard wood. It is not easy to split. However, there are insects that lay eggs and reproduce on this hard branch, or even pests. It is'Yellow Glass Sky Cow'. The glass-eyed sky cow has a white spot on the back and antennae, and the surface of the scab wing is smooth, so it is named'glass'. Until a few years ago, it was mainly distributed in lush broad-leaved forests in the middle and northern regions of Gangwon-do and mountainous areas. But now things are different. Due to the rapid increase in population, tree damage is spreading in southern areas such as Busan, Ulsan, and Jeonju, as well as in metropolitan areas such as Incheon, Bucheon, and Seoul. It is only recently that Maroni, who was planted as a landscape architect in Yeongdeungpo-gu, Seoul, was attacked and killed.

Females of the glass-eyed oxen are wounded on the stems of living willow, gorilla, and maroni, and then lay eggs that are about the size of rice grains. The caterpillars dig inside the sleek bark under the bark and gradually grow and dig into the center of the tree. The tree will rot and interfere with growth and eventually dry out. The caterpillars become pupae in the trees and safely pass through the winter, and become adults and make small, round holes and come out of the tree and mate again. Few species of sky cows indiscriminately inflict such young trees. When you dig through the tree and dig inside, a hole is created, where other insects and pests invade and the second attack begins. Trees can't stand anymore.

Dr. Hyun-Woo Kim of the Nakdong River Management Headquarters, who guided the site of the damage at the Samrak Ecological Park in Busan, confirmed that the time of mass outbreaks of the glass-algae sky was about 2015. In particular, in 2018, the number of individuals was very large, and about 10 were displayed on a single willow tree, and this year, the outbreak was delayed a little as the spring lengthened. He also added that as the number of trees increases, the number of woodpeckers that eat sky cows increases, making holes in the trees, so willow trees will die faster.


What is the reason that the'Yuri-Arak Sky Cow', which has lived in Korea for a long time, but has not caused much damage, has rapidly reproduced beyond the metropolitan area? The question was recently answered. Dr. Seung-Hwan Lee's research team at Seoul National University's Insect Systematics Lab analyzed the genes of free eggs in the country over six years. The results were surprising. Originally, the populations that inhabited the northeastern region, that is, the mountainous regions of Gangwon-do, and the populations that are causing problems in the recent metropolitan and southern regions have proven to have different genes.

In other words, it means that the population causing the problem is from outside. Professor Seung-Hwan Lee of Insect System Classification at Seoul National University, who led the study, said, "It is genetically similar to the population in western China and northern China." The fact that damage is occurring mainly in port cities such as Incheon, Busan, and Ulsan also shows that there is a high possibility that they have been introduced from China through the harbor hiding in wood.

The glass-eyed cattle are making great damage in North America, Europe and China to the extent that they are designated as the '100 World's Most Harmful Exotic Creatures' by the World Conservation Union (IUCN). The problem doesn't stop there. The destruction power can be even greater if a population that grew in Korea meets an external influx population and a hybrid hybrid or hybrid population emerges. Professor Seung-Hwan Lee said, "There is a high likelihood that an organism could harm more plants when a foreign group and a native group meet and become hybrids." As such, the outgoing'glass alley cow' is a problem, but the perceptions of the relevant authorities, such as the Ministry of Environment and the Forest Service, are only at ease. It is because the perception is strong that it is a sky cow that has been indigenous to the past and has not done much damage to native trees such as gorilla trees.


Although the number of free-alarmed cows is rapidly increasing, control measures are not appropriate. It is difficult to spray the control chemicals because it enters the tree and overwinters, and the adult insects do not die well. Recently, a means of controlling using natural enemies has been studied, but no natural enemies have been found. Eventually, if left unattended, the number of invaders will increase as the foreign invaders become ignorant, and the damage may spread to other trees. When the news was aired, government agencies such as the Ministry of Environment, the National Forest Research Institute, and the Quarantine and Inspection Division began to show interest. It was to find out how much foreign pests from foreign countries are harming native trees.

Professor Seung-Hwan Lee points out that "the rate of spread of free-of-glass cows is fast, so we need a strategy to delay the spread first, and it is important to avoid hybridization with native populations." In addition, we emphasize not only strengthening quarantine inspections for foreign pests, but also quarantine to prevent our pests from escaping to foreign countries. This is to prevent domestic influx of varieties. As it has been found that the Akdong Yuri Alaska Cattle, which is causing problems, is an influx population in China, systematic research and support for foreign pests as well as joint research by the government and academia are urgently needed.

For reference, this paper by the research team of Insect System Classification at Seoul National University, which became the subject of the SBS 8 o'clock news, was published in the June issue of the Journal of Pest Science, a world-renowned pest science journal.