How to Identify a Spider Bite: 7 Steps

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How to Identify a Spider Bite: 7 Steps
How to Identify a Spider Bite: 7 Steps

There are thousands of species of spiders around the world, but the vast majority of them have fangs that are too short or too fragile to penetrate human skin. Therefore, spider bites rarely lead to death, depending on the species. However, they can hurt a lot and sometimes even provoke a systemic reaction caused by the poison. The two most dangerous and most worrying species in Brazil are the armadeira and the brown spider. It is important to know if a bite is from a spider or other insects so that you can assess the severity and the need to seek medical attention or not.


Part 1 of 2: Identifying Common Spider Bites

Identify the Spider Bite Step 1

Step 1. Look for a wound with two holes

A sting from a black widow usually hurts immediately and can be distinguished from stings from other spiders and insects by the mark left on the skin. Often a black widow's sting is a little painful, as this spider has long, sharp fangs, but sometimes it can be painless. After the bite, the two holes start to turn red and inflamed and form a lump. Sensitivity at the site tends to increase and spread within an hour.

  • Watch for more serious side effects such as severe cramps (especially in the abdomen), excessive sweating around the bite, nausea, headache, chills, and increased blood pressure. All these symptoms are reactions to neurotoxic poison.
  • The antidote for black widow venom is applied if the bite causes severe pain and other symptoms. It can be given by injection into the thigh or intravenously (serum) by a doctor. However, the antidote can cause severe allergic reactions that further worsen the symptoms of the poisoning.
  • For easier identification, know that the black widow is shiny, rounded and has a red diamond (or hourglass) shaped spot on the underside of the belly. In Brazil, it is more easily found on beaches and in the Northeast.
Identify the Spider Bite Step 2

Step 2. Look for "circle" shaped bites

A brown spider's bite is often painful or causes a slight burning sensation, similar to a mosquito's bite. However, within 30 to 60 minutes, the sting site turns red and inflamed, with a sore in the center. The redness and pain intensify over the next eight hours, the central wound becomes larger, full of blood and ruptured vessels, and a very sensitive ulcer develops. During this stage, the region around the bite usually turns blue or purple, and is often surrounded by a red rim. It is recommended to see a doctor, especially if the ulcer that has formed lasts longer than a few weeks.

  • In most cases, the ulcer heals through the appearance of a peel that falls off in a few weeks, but sometimes this process can take months if the victim's immune system is not strong - which happens more often in children and seniors.
  • There is no antidote to help control the effects of the brown spider bite. Its venom is classified as necrotizing, meaning it kills local tissue, turning it black or bluish.
  • To treat the wound, wash the area with water and a mild soap. Apply ice packs and elevate the affected area to reduce pain and inflammation. Take a pain reliever (paracetamol) or an anti-inflammatory (ibuprofen) if needed.
  • In order to identify it, know that the brown spider is brown or yellowish. She has long, slender legs and her body is made up of a head and an oval abdomen. It is found in quiet and dark places in the most diverse states of Brazil.
Identify the Spider Bite Step 3

Step 3. Pay attention to needle-like hairs on the skin

Although the crab is, without a doubt, one of the most frightening species among spiders, the natives of North and South America are not poisonous and rarely bite. However, this "New World spider" darts across needle-like blacks when it gets agitated and feels threatened. The hairs lodge in the skin and generate a type of allergic (anaphylactic) reaction that involves hives, swelling and difficulty breathing, especially in more sensitive people. Initial pain is usually described as a burning sensation.

  • People who have crabs and deal with them often can become sensitive.
  • The species native to Africa and the Middle East does not have these needle-like hairs, but it is more aggressive and produces venom.
Identify the Spider Bite Step 4

Step 4. Identify other spider bites

Black widow and brown spider bites are the easiest to identify, mainly because they have the most potent venoms and cause the most symptoms. However, spider bites from other species are more common to occur and can cause pain and swelling as well. For example, the tegenaria agrestis is a large, fast spider with yellow marks on its brown back. It injects a neurotoxic venom when it bites that can necrotize the skin around the bitten area, but not to the same extent as brown spider venom.

  • Tegenaria agrestis and clubionidae stings can cause discomfort and an injury similar to a bee or wasp sting, although the initial pain is much less, as the fangs of these spiders are not as large and strong as the sting of a spider. bees and wasps.
  • To identify the type of spider bite you took, capture it and take it to your local emergency room (someone might know how to identify it) or search the internet. Most spider bites are harmless or cause only mild discomfort that goes away on their own after a few days.
  • The procedure needed in this case is just to treat the spider bite with antiseptic gel, ice packs and over-the-counter medications.
  • Generally speaking, spiders only attack to defend themselves, especially if they are crushed or crushed between you and some surface.

Part 2 of 2: Differentiating Spider Bite from Other Insect Bite

Identify the Spider Bite Step 5

Step 1. Remember that most insect bites are more painful than spider bites

Spider bites are often patients' first suspicions, but the belief that spiders are that dangerous is a mistake. For example, insects like bees and wasps have powerful stings and cause a skin wound that does far more damage than a spider's tiny prey. The bee leaves the stinger on the person's skin and dies shortly thereafter while wasps (including wasps) can sting several times.

  • Reactions to bee and wasp stings can range from something minor like redness and swelling of the skin (a small bruise or bruise) to something more serious like anaphylaxis in more sensitive people. In this case, there is a need for medical attention. Bees and wasps do not inject venom, but they are responsible for killing more people each year than spiders because of anaphylactic reactions that are not properly treated.
  • Anaphylaxis is usually controlled with injections of epinephrine (adrenaline) that decrease the body's allergic response. This injection can be given by a doctor or even at home if you have access to epinephrine.
  • The type of spider bite that is most often confused with the bee/wasp bite is the tegenaria agrestis and the clubionidae. The black widow can cause symptoms similar to a bee sting, but the wound generated by the two typical fangs is nothing alike.
Identify the Spider Bite Step 6

Step 2. Watch out for painful scorpion stings

Although the scorpion has claws similar to those of crabs, it uses its tail to sting. Scorpion stings are often painful and cause localized redness and inflammation, but are rarely serious. However, the yellow scorpion can deliver a fatal sting as it produces a potent neurotoxic venom.

  • The mark left by the scorpion's sting is very different from the black widow's two holes, but the pain and other symptoms can be very similar, as both species produce a neurotoxic venom.
  • The scorpion sting antidote is an injectable solution given in an emergency room.
  • As with most spider bites, most scorpion bites can be treated at home using an antiseptic gel, over-the-counter ice packs. But when in doubt, see a doctor.
  • The yellow scorpion (Tityus serrulatus) is typical of the Southeast and Midwest of Brazil.
Identify the Spider Bite Step 7

Step 3. Don't confuse tick bite with spider bite

A tick bite is often confused with a brown spider (and vice versa), as both can produce a similar skin reaction. Some ticks can be vectors of Lyme disease, so they shouldn't be overlooked. Symptoms of Lyme disease tick bites are: concentric ring rash that may appear up to a month after the bite, fever, fatigue, headaches, muscle and joint pain.

  • The main difference between the brown spider bite and the tick bite is that the tick bite, at first, does not hurt and never generates an ulcer (necrosis) on the skin of the site.
  • Another difference is that the tick usually penetrates the skin before infecting the host, so you can sometimes see it under the top layer of skin. Spiders, however, do not lodge on people's skin.


  • To avoid spider bites, wear long-sleeved shirts, hats, gloves, and boots when cleaning backyard sheds, garages, basements, attics, and dark, low-lying spaces.
  • Always look inside gloves, boots, and clothing that has been left unused for some time. Give them a good shake before putting them on.
  • Using insect repellent on clothing and shoes can ward off spiders.
  • If you get a painful spider bite and are far from an emergency room, apply ice to the wound immediately. Then apply an antibacterial gel and other first-aid supplies that help prevent infections.
  • As there are thousands of species of spiders around the world, be careful when traveling abroad, especially to countries in South America, Africa, Southeast Asia and Australia. Other very dangerous and noteworthy spider species across the planet are the armadeira spider (also present in Brazil), the Australian funnel spider, the rat or missulena spider, the Latrodectus hasseltii ("red black") and the wolf spider.


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