Don't rush to take a picture of a bug on your face! The unique skills of the fart beetle, the "disfigurement" of chemical weapons is too scary

Recently, there was a news report that a citizen in Yixing was burned on the face by an insect at home. The injury was quite severe, and many large blisters appeared on the face. Later, the citizen took the insect that was killed to the hospital for treatment. The doctor diagnosed her with "poisonous insect sting and chemical burns" and told her that the insect was called a fart beetle. What kind of insect is a fart beetle? Why does it sting people and cause chemical burns?

The news said that the fart beetle is the "cantharidin" written by Mr. Lu Xun in "From Baicao Garden to Sanwei Bookstore". In fact, these are two different insects. In the dialect of the southern region, cantharidin generally refers to large beetles of the family Meloidae. They often have brightly colored spots on their bodies. When stimulated, they will secrete sticky yellow body fluids from the joints of their bodies. The fluids contain toxins such as cantharidin, which are highly irritating to the human body and can cause skin redness, swelling and blisters. If more than 10 mg enters the body, it may cause poisoning of the urinary system and digestive system, and in severe cases may cause death. However, cantharidin does not make a popping sound or spray smoke. Beetles with this special ability are called fart beetles.

Fart beetles, also known as air beetles, are not a type of insect, but a general term for a class of insects. Generally speaking, any species under the subfamily of the family Carabidae in the order Coleoptera of the class Insecta can be called fart beetles. Fart beetles have a unique skill - spraying chemical weapons. When they are disturbed, they will spray a stream of smoky liquid from the end of their bodies, and they will also make a popping sound, just like farting, which is why they are named fart beetles.

The main components of the fart of the fart beetle are benzoquinone and methylbenzoquinone. The abdomen of the fart beetle has a special structure, which contains glandular cells that can secrete hydroquinone and hydrogen peroxide. The fart beetle will store these two substances separately in a sac-like "storage tank". When it needs to fart, the fart beetle will open a valve-mounted structure that acts as a "valve" to mix hydroquinone and hydrogen peroxide. After the two substances meet, catalase catalyzes the decomposition of hydrogen peroxide into oxygen and water. Oxygen, catalyzed by peroxidase, oxidizes hydroquinone into benzoquinone. This chemical reaction process is very intense. When the liquid gushes out under the action of strong pressure, it will produce a high temperature of nearly 100°C and a peculiar smell. Generally, small creatures will flee in a hurry when attacked by this chemical weapon.

Generally speaking, if the fart of a fart beetle sprays your fingers, you will feel a strong burning sensation, but the symptoms of the woman in the news rarely occur, probably because the skin on the hands is thicker, while the skin on the face of women is thinner and more delicate. In addition, when the fart beetle is attacked, it may spray multiple times quickly, causing too much liquid to be sprayed on a small area of ​​the woman's face, resulting in such a serious chemical burn.

Fart beetles are generally more active at night. During the day, they hide in areas such as grass and cracks in rocks. After dark, they crawl out to prey on other small insects and other invertebrates. Many of the prey they catch are pests in agriculture and forestry, and they are predatory natural enemies. From this perspective, fart beetles are an insect that is beneficial to agriculture and forestry.

Of course, although the fart beetle is a beneficial insect, if you are hit by its "fart", it may still burn your skin. So if we encounter it in the wild, or see an insect with bright spots or stripes on its body, it is best not to touch it directly with your hands. If you feel a bug crawling on your body, don't rush to kill it. You can gently blow it away or shovel it gently with paper and shake it off to the ground. It is best to install gauze curtains and screens on the doors and windows of your home to prevent it from entering the room. If you find a fart beetle indoors, you can hold it in a small container, insert a piece of paper from the mouth of the container, turn it over, catch it, and throw it outside. If too many fart beetles enter the room, you can also use an appropriate amount of insecticide to drive them away.

This article is a work supported by the Science Popularization China Creation Cultivation Program

Author: Li Weiyang, science writer

Reviewer: Yin Haisheng, Senior Engineer, Researcher, Shanghai Insect Museum, Chinese Academy of Sciences

Produced by: China Association for Science and Technology Department of Science Popularization

Producer: China Science and Technology Press Co., Ltd., Beijing Zhongke Xinghe Culture Media Co., Ltd.