Why does a mosquito bite make it itch more the more I scratch it?

Audit expert: Jiang Tao

Vice Chairman of the Science Popularization Committee of the Chinese Society of Bioengineering

In the hot summer, when you are immersed in dreams or enjoying the breeze outdoors, there are always some "uninvited guests" - mosquitoes, which seem to have a special liking for our blood.

Image source: Internet

The main flood season in Beijing is coming, and the precipitation has increased significantly. Coupled with the high temperature, it is the period of mosquito breeding in the north of the year, and the probability of us being bitten by mosquitoes will also increase. Today, let's learn how to prevent mosquitoes from sending "red envelopes".

Where do the uninvited guests come from?

Mosquitoes have a special liking for humid places, and they usually reproduce in still water, such as ponds, lakes, containers of stagnant water, etc. Mosquitoes are typical insects that undergo complete metamorphosis. The larvae of mosquitoes are called jié jué. They spend their childhood in water, breathe through gills, and become adults by pupating.

Image source: Internet

Mosquitoes are widely distributed around the world, and can be found in almost every corner except the polar regions. Mosquito larvae in nature have strong adaptability, prefer humid environments, are not "squeamish" or picky eaters, and bacteria and single-cell algae in the water can become their delicacies.

In addition, mosquito breeding grounds also include rivers, construction sites, idle land, sewer wells, building roofs, open-air swimming pools, various types of idle outdoor water containers, as well as indoor breeding grounds such as underground garage collection wells, water storage tanks, flower pot trays, and aquatic plants.

Therefore, the plant trays in our homes, or even the beverage cans you forgot in the corner, may become the spawning grounds and "resorts" of female mosquitoes. Therefore, good water management in various environments can effectively reduce the density of mosquitoes. It is best to change the water for growing flowers and fish at home every 7 days. If there are bottles and cans in front of and behind the house, they should be turned over or directly discarded to avoid water accumulation.

Why do mosquito bites make you itch the more you scratch them?

When a mosquito bites, it uses special mouthparts to pierce human skin to suck blood. To be precise, the mosquito relies on our blood pressure to get blood. At the same time, it also injects its saliva containing anticoagulant and anesthetic components into our skin. This saliva can cause our blood vessels to constrict, blood coagulation, platelet aggregation, angiogenesis, and reduce immunity, thereby producing inflammation.

The lumps and itching after being bitten by a mosquito are caused by an allergic reaction to the mosquito's saliva. This is because after the mosquito's saliva is injected into the human body, our immune system will quickly recognize it, mainly mast cells will release a substance called histamine, which will produce an inflammatory response, causing mosquito bites to form on the skin surface and produce a tingling sensation.

The stimulation of mosquito saliva on nerves will prompt us to scratch the bitten area. If we continue to scratch, it will further stimulate the nerve endings, causing the body to release more histamine, forming a vicious cycle of "the more you scratch, the more itchy it becomes". At the same time, it will cause further breakage of protein fibers such as collagen in the extracellular matrix between cells, aggravating edema.

Image source: Guangdong Science Center

In addition, if you accidentally scratch your skin, it will increase the risk of infection.

Therefore, it is recommended that you do not scratch your skin excessively after being bitten by a mosquito. You can choose to apply cold compresses or antihistamine ointment to the bite to quickly reduce the temperature of the red and swollen skin tissue, shrink capillaries, and reduce inflammatory reactions. If a large bulge of skin tissue appears, the affected area is obviously red and swollen, and the above treatment does not subside, you should seek medical treatment in time.

Take these mosquito repellent "amulets"

So, how can we avoid mosquito bites? Here are some tips for mosquito prevention:

Invisibility Cloak

First, try to wear long-sleeved clothes and long pants. Mosquitoes cannot penetrate tightly woven clothing, and many synthetic fibers (especially high-tech sportswear) are often woven tightly enough to effectively block the penetration of mosquito proboscis, creating a physical barrier to the skin.

Alternatively, choose light-colored clothing with a tight weave. Mosquitoes use their vision to find food sources during the day. Since they fly so close to the ground, mosquitoes tend to look for objects that contrast sharply with the horizon to identify their feeding targets.

Image source: Guangdong Science Center

Magic Barrier

Secondly, DEET is a traditional mosquito repellent ingredient. It is widely used in various mosquito repellent products based on the principle that mosquitoes rely on the carbon dioxide exhaled by animals to find blood sources to feed on. It works by blocking the mosquito's carbon dioxide receptors. You can choose to apply no more than 30% of DEET to your ankles, elbows, wrists, forehead and other parts of your body where the skin is thin and easily bitten by mosquitoes.

Image source: Internet

Planting mosquito repellent plants such as citronella, lavender, lemongrass, marigold and basil can also have a certain mosquito repellent effect.

Technology Assistance

In addition, you can also use mosquito repellent items such as mosquito nets and electric mosquito swatters to prevent mosquitoes from hiding. However, it should be noted that although electric mosquito swatters are good, you must be careful when using them, as they can also "bite people". After using the electric mosquito swatter, make sure to turn off the power and place it out of the reach of children.

Image source: Internet

Although mosquitoes are small, the troubles caused by their bites should not be underestimated. Anti-mosquito is not only for comfort, but also for health. Understand the preferences of mosquitoes and the secrets of itching, and equip our "anti-mosquito secrets". Summer nights are long, and I hope we can all enjoy the cool evening breeze and sweet dreams in a mosquito-free environment.