Mosquito Bite vs Spider Bite

Illustration of insects that can sting

Mosquito Bite

Contrary to what you know, mosquitoes don’t actually bite and only female mosquitoes “bite”. When a female mosquito bites, it uses its proboscis, a large needle-like mouth part, to pierce through the skin and look for a blood vessel. Once she finds a blood vessel, she sucks out some blood. She needs the protein from human blood to develop and lay its eggs. Mosquitoes suck out blood with force resulting in a collapse or rupture in the tiny blood vessels. While the mosquito is sucking blood, it leaves behind its saliva which acts as an anticoagulant for her to feast on your blood more quickly and more efficiently without you noticing it right away. The saliva constricts the blood vessels to prevent the blood from clotting once it is punctured. The saliva contains enzymes which the body is allergic to because they are foreign invaders. This results in the production of histamines by mast cells as the body’s response to the foreign invading enzymes. This is causing the itchy and sometimes swollen and reddish bump on the skin after a mosquito bite.

People have different reactions when it comes to mosquito bites. Some people feel the itching and swelling right away while it takes time for some to notice the itching and swelling. There are others who probably have been immune to mosquito bites that they don’t feel the itching and swelling any longer.

The itching brought about by mosquito bites is annoying but most of the time, a mosquito bite is harmless. You should be aware though that there are some mosquitoes that can spread viruses and bring about illnesses such as West Nile Virus (WNV), dengue fever, yellow fever, malaria, Chikungunya, Zika, and encephalitis. Symptoms of these more serious illnesses usually show up after a couple of days or even weeks after the appearance of the itchy bump.

Mosquitoes are most active during dusk and at night although you can get mosquito bites at any time of the day. Mosquitoes appear the most in places that are hot and humid so when the temperature reaches 50 degrees, they may appear a lot. Mosquitoes are seen the most when temperatures rise during the summer.

Spider Bite

When a spider bites, on the other hand, it injects a venom from one or two “fangs” called chelicerae. These two tiny vampire-like bites disappear. The bites look similar to a mosquito bite but it will most likely hurt more than an itch. Spider bites don’t carry diseases, unlike mosquitoes. There are some spider bites such as brown recluse bites that are sunken or flat instead of swollen. Some spider bites may blister and become inflamed after a week just like some recluse bites. Spiders only bite as a defense mechanism so there are a lot of alleged spider bites that are not spider bites at all. There are only a few species of spiders that carry venom that can make a person sick such as the Australian redback, the Sydney funnel web, and the American black widow. Spider bites rarely cause a necrotic skin wound or severe pain.

When you start to feel other symptoms such as fever, headache, nausea, dizziness, sweating, chills, tiredness, difficulty swallowing, joint pain, facial swelling, difficulty breathing, or cramps after a spider bite and you are fully aware that you live in a toxic environment, immediately seek medical attention. You can describe the symptoms of the bite to the doctor but let the doctor diagnose you. Do not immediately tell the doctor that it’s a spider bite because you might be diagnosed wrongly. Remember that mosquito bites from infected mosquitoes that carry viruses are more deadly than spider bites even if spider bites tend to cause a severe reaction.

Spiders are around all year long even if you don’t see them. House spiders are usually visible during late summer and early autumn.


The bump caused by a mosquito bite and a spider bite may look similar. Both bites are also dry. If there is a fluid or pus coming out of the bump, it means that you have a secondary infection from too much scratching or for not keeping the wound clean.


Mosquito bites leave a pinkish itchy bump on the skin and in rare cases, call for a severe allergic reaction to it. Mosquito bites are round and puffy bumps that appear immediately right after being bitten by a mosquito. The bump soon becomes swollen, pinkish or reddish, and hard. It is possible to have multiple bites in the same area of the skin.

Spider bites cause red skin, pain, and swelling of the bite itself or very serious symptoms that require immediate medical attention. Spider bites cause two puncture or vampire-like marks on the skin that is painful and causes a burning sensation. There is itching, redness, and pain around the area of the spider bite. It may cause a purple or red blister or rash at the site of the spider bite. The spider bite can be a blister that may burst and ulcerate. It could also cause other symptoms such as a headache, nausea, sweating, fever, dizziness, chills, tiredness, or muscle pain.