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What's the Difference Between Bed Bug, Mosquito, and Spider Bites?

Updated on July 16, 2017
Bedbugabscond profile image

Melody has volunteered with the CDC and is a member of the Medical Reserve Corps. She brings awareness to public health concerns.

Bed bug bite (by hiroo yamagata on flickr); spider bite (by Jinger on flickr); and mosquito bite (by Josh).
Bed bug bite (by hiroo yamagata on flickr); spider bite (by Jinger on flickr); and mosquito bite (by Josh). | Source

Identifying Bites and Rashes

It can be difficult to distinguish between various kinds of bug and insect bites—not to mention fungal rashes, allergic reactions, and poison oak and ivy. Mystery bites are alarming. That is when the mind starts to wonder about fleas, mosquitos and bed bugs.

Symptoms of mosquito bites, bed bugs, and allergic reactions look similar. There are, however, some characteristic differences. For example, There are a lot of bites that look like bed bugs but aren't. With thousands of rashes existing worldwide, your doctor is the only person who should be examining you.

Unfortunately, your doctor can't always tell what bit you by looking at the bite. They will want to know as much information as they can. If you can present them with a picture of what bit you, then you are likely to get a positive identification.

I know you are probably feeling worried about your bite, but don't panic. If you are having a serious reaction call your doctor right away. If not then continue collecting information.Bud bugs might not spread diseases, but they can cause severe allergic reaction in some people.

Bud bugs might not spread diseases, but they can cause severe allergic reaction in some people. Fleas and mosquitos do cause disease. It makes you wish there was a definitive way to test for insects and arachnids.

Make a symptom list by asking yourself the following questions:

  • Where did I get the bite?
  • What part of my body is the bite on?
  • Are the bites in clusters?
  • What season is it? It's unlikely for mosquitoes to bite in winter.
  • Where did exposure happen?
  • Have I been outside or spending time at others' homes?
  • Does my home show signs of infestation?
  • What is the duration of the rash?
  • Does it come and go?
  • Do you have previous skin conditions?
  • Are there local public health warnings about a certain pest?
  • Does your pet have fleas?

Answering these questions may help you discover the culprit and might be information your doctor needs.

Basic Differences Between Bed Bug vs. Mosquito vs. Spider Bites

Mosquito Bite
Bed Bug Bite
Spider Bite
Raised welts that appears randomly on the body
Flat, red dots that may or may not be in groups of three.
Singular bite that can be red and itchy; sometimes has puncture marks from fangs
Bites qickly turn into itchy red welts
Bed bug bites do not start itching until later for hours or days
Spider bites' anticoagulant wears off slower, causing itchy red bumps or a rash to appear later
Mosquito bites on a child's thigh. It is unusual to have so many. Poor kid!
Mosquito bites on a child's thigh. It is unusual to have so many. Poor kid! | Source

Bed Bug vs. Mosquito Bites

Mosquito bites are commonly mistaken for bed bug bites, especially if the bites happen in bed at night. Both creatures bites can induce allergic reactions. They appear immediately after exposure or later, as body chemistry affects the timing of the reaction.

Only doctors can tell you what your rash is, and even they might have difficulty with identification. The key is thinking like your doctor by gathering information. You already have a list to show your doctor, if you answered the earlier questions.

Mosquito Bites

Mosquito bites appear in isolation, grow quickly, and resolve themselves. It's less likely to be bed bugs when there are only a few red areas. Resist the urge to scratch to prevent misdiagnosis of your rash.

The diameter of the bite depends on the person, the size of the mosquito, and length of time the mosquito labium pierces the skin. However, the bites can get quite large. Unlike bed bug bites, irritation almost always begins at the time of the bite.

According to the Mayo Clinic, the symptoms of a mosquito bite are:

  • Pale bump that appears lighter than the surrounding skin.
  • The area around the bite may appear red.
  • Initially, a soft bump that turns hard when scratched.
  • The bump may turn red.
  • Itchiness.

If you look at the bump and still can't tell, ask yourself:

  • Have you been outdoors a lot? (If so, it's more likely a mosquito.)
  • Have you seen black, red, or brown smudges on bed sheets? (These may be bloody signs of bed bug bites.)

Bed Bug Bites

Bed bug bites are clustered, red and unraised. Mosquito bites become inflamed faster than bed bug bites. If the bites linger for weeks, then you might have bed bugs.

Bites almost always appear in clusters. Sometimes, they don't look like bites or a rash at all. Instead, they may look like welts. Some people never develop a rash.

These bloodsuckers split each feeding session into courses. One of these tiny vampires causes three red dots. Attuned to exhaled carbon dioxide, the location of the bites may be consistent with bed bugs. Bed bugs are usually found near the head of the bed and spread from there.

Inspect the entire bed using your rash as a clue. For example, if you sleep on your back, on the left side of the bed, then check the mattress edges in that location.

Be cautious about self-diagnosing bed bug bites. Look for live specimens, clusters of bed bugs, dead bugs, discarded exoskeletons, or bug feces (rusty-looking stains). Check your bed, furniture, and car.

Bite Comparison Table: Spiders, Mosquitos and Bed Bugs

Spider Bite
Mosquito Bite
Bed Bug Bite
What you feel at time of bite
Bite feels like a sting, or is not felt.
Bite starts to itch immediately.
Not felt until hours or days later.
When you'll notice something
Immediate skin discoloration after bite.
Inset bite that turns red right away.
Does not turn red until anticoagulant wears off.
Number of bites that occur at once
Bites are usually singular, or dual.
Bites may be close by coincidence only.
Bites come in groups of three, unless bugs were interrupted while feeding.
Appearance over time
Usually has redness and is accompanied by puncture wounds from fangs.
Raised welt or rash that grows quickly.
After a few hours, each bite turns into a red circle, or dot.
What it looks like at the center
Center is red, with two small holes (bite itself).
Center is white at onset.
Center is red, and uniform with rest of rash. They are never white.
Who experiences a reaction?
Rash caused by venom.
Almost everyone bit by mosquitoes has a reaction.
Only some people get a rash. Some have no symptoms.
Common bite location
No specific body part is preferred.
Bites happen anywhere on uncovered skin, with mosquitoes preferring the upper torso.
Bed bugs are attracted to carbon dioxide (we breath this out), so most bites are near the head (but can be anywhere).
How long reaction takes to develop
Can take minutes to hours to develop symptoms.
Reaction happens in minutes.
The reaction may take as long as 14 days to develop in some people, and appears instantly on others.
Level of danger
Some venemous spider bites can be life-threatening.
Mosquito bites are an annoyance to all, but can be serious to those who are allergic.
Bed bug bites may rarely spread disease, and are not life-threatening.
Cause of bite
Bite caused by a pair of fangs.
Bite caused by needle-like tube called a labium.
Bite caused by two tubular mouthpieces.
Substance that is injected
Contains anticoagulant and enzymes.
Bite introduces anticoagulant, and brief skin numbing agent.
Bite contains a longer lasting pain killer, skin numbing agent and anti-coagulants.
What kind of creature
Not an insect an arachnid.
Is considered to be an insect bite.
Bite comes from an insect.
Many spider bites can be treated on your own at home. However, venomous spider bites can be painful and even deadly, and can require medical treatment.
Mosquito bites can be treated with home remedies, and almost never need medical treatment.
Bed bug bites are almost never treated by a doctor, and can be treated at home.
Time of year most common
Can happen any time of year, even in winter. Spiders find homes in houses and garages.
Bites only appear in spring, fall and summer. Where it gets cold, mosquitoes are not a problem in winter.
Happens year round. However, bed bugs are less active in extreme cold; few bites happen during winter.
Bed bug bites: Hours after feeding.
Bed bug bites: Hours after feeding. | Source
Sometimes, bed bug bites look like welts.
Sometimes, bed bug bites look like welts. | Source
Bed bug bites often appear in a line or cluster.
Bed bug bites often appear in a line or cluster. | Source

Which Bite Is the Worst?

Mosquito bites are far more dangerous than that of a bed bug because they transmit diseases such as malaria, West Nile Virus and Zika. Plus, they occasionally cause severe reactions in some people, so severe they need medical treatment.

You can call your local CDC to find out if these diseases are an issue where you live.

Bed bugs are not known to spread disease. Scientists thoroughly monitor bed bug epidemiology, and if they learn anything different, they will tell us. There was misinformation about the spread of Chagas. While scientists were researching it, some reporters jumped the gun.

They created a rumor that bed bugs can spread the disease. They used incomplete information to draw their conclusions. Now that the U.S. and Peru have finished their joint study, we know that bed bugs can not spread Chagas.

The antigen that mosquitoes use is not nearly as long-lasting as that of bed bugs. That means that a mosquito bite will not continue to bother you the way a bed bug bite will.

People with mosquito allergies have severe reactions to bites compared to those who are considered to be mosquito sensitive.

While bed bugs don't spread disease, they can cause financial disaster. Even though they are less dangerous, you must still discover everything you need to know to solve your problem.


Preventing bed bugs is better than getting them. If you suspect you have a bed bug infestation, take action immediately. The longer you wait, the harder (and more expensive) getting rid of them becomes.

It isn't uncommon for people to pick up bed bugs at hotels or while staying in other peoples' homes. To keep unwanted travelers from returning home with you, then inspect the bed and mattress where you plan to sleep.

If bitten by what you think is a bed bug while traveling, unpack your suitcase outside of your home. Carefully run laundry through a wash and hot dry cycle. Take steps to dis-infest your suitcase, too.

Poison Oak Rash

Poison oak rash: Two weeks after exposure.
Poison oak rash: Two weeks after exposure. | Source

Poison Oak or Poison Ivy Rash vs. Bed Bugs

Bed bug and mosquito bites have very little in common with poison oak/ivy. Mosquito bites do not resemble poison oak or ivy.

All three types of rashes have the same reddish coloring and appear as a cluster of raised welts. However, bed bug and mosquito bites do not usually cause puss filled blisters the way that poisonous plants do.

A normal bed bug bite reaction will not have puss blisters or seep liquid, but a serious bed bug bite reaction that has been scratched might cause an open wound that looks like poison ivy.

Poison oak and ivy are creeping rashes that appear over time. If you rinse the affected area immediately after expose, then you may never get a rash.

Poison Oak vs. Bed Bugs Symptom Comparisons

Poison Ivy/Oak Rash
Bed Bug Bites
Red coloring
Comes in clustered groups
No, unless scratched and infected
Itchest at onset
No, unless infected

Which Is Worse?

The problem is that a seeping poison ivy rash may not be serious, where a seeping bed bug rash is. An oozing bed bug rash is a sign of a serious allergic reaction that should be treated by a medical professional.

Poison Ivy and Oak can spread. When a poison plant rash is oozing, it is still contagious. Even people with minor reactions will be in a serious state if it is spread to the eyes or respiratory tract.

These plants leave a residue on skin and clothing. If you think you have poison oak, ivy, or sumac, then carefully wash all clothing items that may have come in contact with the surface.

Poison Ivy Rash

Poison ivy rash: Blisters may appear.
Poison ivy rash: Blisters may appear. | Source

Spiders vs. Bed Bugs vs. Mosquitoes

Because there are more than 20,000 different types of spiders in the U.S. alone, and because each kind of spider bite looks different and causes a different reaction, it's hard to make sweeping generalizations about spider bites as a whole. But still, it's important to recognize a spider bite when you see it.

Most spiders are at least a little bit poisonous, at least to their prey, although humans are mostly safe. If a spider does bite you, it usually won't cause a serious problem. You may see a visible reaction, it may hurt or itch, and you may even develop a blister, but usually that's the extent of it, and it usually disappears within a week or so.

Of course, it's much easier to diagnose and treat a spider bite if you saw the spider that bit you, but sometimes you may not even notice the bite until hours later. Look for things like pain, itching, burning, inflammation, redness, and skin damage. Sometimes you can see two puncture marks on the skin at the center of the reaction.

Spider bites take longer to heal than those of mosquitos and bed bugs. Spider bites may affect skin tissues in a more destructive manner. It's important to keep the bite clean to reduce the risk of infection. Unlike bed bugs, spiders are solitary creatures and usually only bite once, so if you see a cluster of bites, it was probably not a spider.

However, a few spiders can cause serious problems. If you experience fever, chills, rash, swelling, nausea, vomiting, heavy sweating, drooling, headaches, rapid heart rate, changes in blood pressure, muscle pain, anxiety, swollen lymph glands, or difficulty breathing, then you should see your doctor.

Example spider bite.
Example spider bite. | Source

Which Is Worse?

The answer depends on the type of spider. As noted, most spider bites are relatively harmless and will heal within a week or so, but if you notice any of the symptoms listed above, you'll want to see a doctor immediately.

A very scary-looking spider bite.
A very scary-looking spider bite. | Source

What About You?

What kind of bite or rash do you think you have?

See results

Bed Bug Bites vs. Other Skin Conditions

Mysterious Skin Condition. Not Bed Bug Bites.

We don't know what this is, but it is not bed bug bites.
We don't know what this is, but it is not bed bug bites. | Source

The number of rashes in the world is endless. The above picture is of an unknown dermatological condition.

This mystery condition is made up of small red circles. The difference between this and a reaction to bed bugs is that they are raised bumps, not flush with the skin. They have also been there for over a month.

A rash that vanishes, then reappears in the same place is unlikely to be a mosquito bite.

Bed bug bites have usually disappeared well before then. A person might get new bed bug bites in the same location, making them think that bed bug bites linger, but they do not. Of course, the exception is with someone who has a serious allergy.

If you have an unidentified rash, it is important to see a doctor. Children must always see a doctor for a mysterious rash. They are more likely to get one of the five major rash diseases, which can be dangerous.

© 2012 Melody Trent


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    • profile image

      Joan 11 days ago

      I wake up with a bleeding,itching almost scrape like spot on tops of feet or on arm. Only one a night. I recently washed all linens in hot water and dried in hot dryer. I sprayed the entire bed with a bug (recommended for household insects) spray.also all around the room. Any ideas? This only affects me not my husband. Also I wear oxygen 24/7.

    • profile image

      Nina Lasant 3 weeks ago

      "Bite" appeared suddenly as a very red blotch with 2 black spots. There also was a track of red looking puncture wounds L shaped which led to this ugly, scary flat rash. The 2 black parts could have been dark purple. It's on my left forearm on topside. It doesn't itch but I'm itchy on left side of scalp and there's a similar rash without the black spots on left quadriceps. Help!

    • Bedbugabscond profile image

      Melody Trent 5 weeks ago from United States

      Cakie :I can't say for sure what it is. However, since you said red ring, I would see a doctor. Ringworm does cause a red ring. However, tick bites can have a ring, too. Lyme disease sometimes starts that way. Ticks are really bad this year.

      Also, you mentioned a staff infection. Some of those, such as Mersa, can become dormant in your system. This means you are more likely to experience another staff infection. I would talk with your doctor to rule that out.

      Evelyn: I hope you are feeling better. I am surprised the ER did not do more. It could have been a wasp, yellow jacket or bee. Some people can get very serious reactions. Many people take Benadryl for the symptoms. However, if you felt like you were going to pass out, it may signify that you have an allergy to whatever bit you. I would follow-up with your family doctor and talk about the possibility of having a serious allergic reaction.

    • profile image

      Cakie 7 weeks ago

      I have a bite on my arm, two actually. They started out as itchy little rings, like a spaggetio was poking out my skin. It was very itchy. I've gotten it before, and my mom says were waiting till tomorrow to see if it's that THAT bad. If the swelling doesn't go down then I dont know what shell do. I thought it was ringworms, but I searched up what they look like, so, it's not ringworms. But JESUS ALMIGHTY THEY ITCH AND HURT. They don't itch if nothing touches them, but when something touches it, well, it's the reason I'm writing this at 4:30AM. Can you tell me what it is? They've turned into big welts. It looks like glasses without the middle connection. PLEASE PKEASE HELP. I have camp in a week and I didn't get to enjoy it well last year because I has a staff infection. I really don't want that this year. It's raised, no color change, no bite marks, big, shaped like an eye, itches/hurts, and I want to ball up and cry, then rub sand paper on my arm.

    • profile image

      Random 10 months ago

      What about oak mites there bad this year got an article on that?

    • Bedbugabscond profile image

      Melody Trent 11 months ago from United States

      Karinethemom, I know your pain. I bought a house that had set empty for two years. We are also in the middle of a spider problem!! Spiders are far more resilient than other bugs when it comes to being able to survive pesticides. Exterminators use a special pan for them. However, with it being in your sons room, I can see how you might not want to go the chemical route. Right now what is working for us is white vinegar.

      Make a white vinegar spray:

      1. Get an empty spray bottle.

      2. Use a 4:1 ratio of vinegar to water.

      3. Spray all of the cracks, crevices, behind the dresser, around the bed and anywhere you think they might hide.

      I know that doesn't smell great so you could try a essential oil, such as lavender cinnamon or tea tree oil and mix that in a spray bottle.

      Fall and early winter is mating season for spiders. That means you might see increased activity as they try to find appropriate mates.

      There has t be a nest someplace near where you are seeing the most of them. If it is inside the wall that can be a problem. If that is the case then you can try sealing the cracks and walls with caulk. I have an article about using caulk to seal to prevent bed bugs, but doing it for the same reason for spiders would be very similar.

      When you are looking for the nests, look in places you won't expect. For example, I found spiders trying to make a nest in the underside of the drawer of my dresser. Of course, I didn't know until I pull the drawer out and turned it upside down.

      I know spiders, and their bites, are really annoying. I hope some of this information helps you and your son!

    • profile image

      Karinethemom 11 months ago

      My son is getting better by what I was able to determine are spiders at night. My question is how can we keep then.... we washed bedding and bedframe, night tables. This evening before sending him to bed I decided to check his bed since it was late and dark in his room. To my surprise I saw 3 spiders on the wall and ceiling. I had found one in his toys box as well as few hours earlier. Please help. I'm at washing his walls and ceiling with javex.

    • profile image

      That Guy 11 months ago

      I'm pretty sure spider bites are not caused by insects.

    • profile image

      Colleen 11 months ago

      I do NOT see anything here like the big red hot painful bite or sting I got in my own bed.

    • profile image

      Cat 12 months ago

      No clue what I have but I do think it's plant based. I have a lot of skin issues, if it causes a rash or makes you itch, I'm alergic to it. I get scars from mosquitoes and I have had bed bugs before ( worst experience of my life no joke) which I had to go to the doctor for due to their severity. Grew up on a farm and got bit by spiders a lot so i know what that looks like but this "rash" on my arm is just weird. It's not really acting like poison ivy, yet it doesn't look like a bite either. I think I got it while picking Okra in my grandmother's garden, I remember some plant kept jabbing my arm. At the time I didn't think anything of it other than annoyance. That was almost 2 weeks ago and I'm still in a battle with it. It's better, but I have to keep medicine on it 24/7 or welts reappear. It's so weird, I've never had anything like it, and like I said I've had almost any skin irritation possible.

    • profile image

      susan 13 months ago

      We have chiggers in our area, and wondered if you have any ideas on how to stop the itching from them, we forgot to put on a spray to prevent them from bothering us, but won't from now on!

    • profile image

      Sara 14 months ago

      A raised bump but it has two right next to each other and it looks like a spider bite mixed with a mosquito bite. The center is white but it is very heated around the area and it was very sensitive. It is so raised I can feel the bump through jeans. I have tried cortisone and aloe, I also tried a aspirin paste but nothing helped. No visable point of puncture or scabbing over.

    • profile image

      Richard 17 months ago

      First it started just like pimple but then it got as wide as a button on a shirt hard around the edges with soft sking around the edge

    • profile image

      Bite me 22 months ago

      I am getting bitten by mosquitos (I believe) when I sleep. I know it's not bed bugs because I have encountered them several years ago and actually had an allergic reaction to them. By the pictures you provided, it is mosquitos bite. I don't even want to sleep in my own bed (and my husband isn't getting bit). Why am I only getting bit at night (in my bed)?

    • profile image

      Hello 2 years ago

      I had bed bugs before so when I get bit, I am nervous. I just got back from vacation and I am so itchy. We were at a park all day for two days so I'm definitely thinking mosquitos because I checked the lining of the bed before I laid down the first night at the hotel. When I had bed bugs it was really odd because of four people I was the only one that had a reaction and the smaller black bugs would hide in the corners of the room.

    • profile image

      Me 2 years ago

      If you're worried about bed bugs check the plastic cups of your box spring they like to hide in there... i had to deal with the nightmare of them. At first i thought they were mosquito bites. . Boy, was i wrong. It makes you feel helpless and disgusting and extremely vulnerable. I made it out bug free, but now i freak out at the sight of any bite. Just please be wary buying secondhand furniture and where you move into and even where you stay! Luckily/unluckily my skin reacts to them. I knew something wasn't right after only living there for not even 2 weeks and wish it would have clicked sooner and never had bed bugs in my life before! Apparently another tenant in the building had brought them in! I wish them on no one. I wish anyone the best if they have them. Bombing will not work!

    • bethperry profile image

      Beth Perry 3 years ago from Tennesee

      I've never seen a bed bug in life, but have heard some awful stories of the damage they can inflict! Quite useful info, and appreciate the photos you included.

    • profile image

      areniomma 3 years ago

      I'd personally also like to convey that most individuals that find themselves with no health insurance are normally students, self-employed and those that are out of work. More than half on the uninsured are really under the age of Thirty-five. They do not think they are requiring health insurance as they are young in addition to healthy. The income is frequently spent on houses, food, as well as entertainment. Many individuals that do work either entire or not professional are not made available insurance by their jobs so they get along without with the rising cost of health insurance in america. Thanks for the suggestions you share through this website.


    • KenDeanAgudo profile image

      Kenneth C Agudo 4 years ago from Tiwi, Philippines

      Great information. I never experienced being bitten by a bed bug but a mosquito! quite irritating whenever you are sleeping and buzzing all around your ears.

    • Mel Carriere profile image

      Mel Carriere 4 years ago from San Diego California

      My Grandma used to send me off to sleep with the warning "Don't let the bedbugs bite," but the truth is I've never seen one. Thank you for raising our awareness on this issue.

    • Bedbugabscond profile image

      Melody Trent 4 years ago from United States

      Glad to hear you have never had to deal with bed bugs! They are nasty critters! I am like you and get eaten up by mosquitoes. Now I use skin so soft to keep them away. It really works, and it is natural!

    • epbooks profile image

      Elizabeth Parker 4 years ago from Las Vegas, NV

      All of a sudden feeling all itchy! :) This is a helpful article, because I'm the first person that gets bit by mosquitoes. When we vacationed in Hawaii, we went hiking and I got bit quite a few times. Never had any bed bugs though- so I am happy about that! Voted up and usefuL!

    • mercuryservices profile image

      Alex Munkachy 4 years ago from Honolulu, Hawaii

      Don't let the bed bugs bite.

    • peachpurple profile image

      peachy 4 years ago from Home Sweet Home

      thanks for showing the pictures between bug bites and mosquito bites. Really looks almost the same! My son and I had both and couldn't see the difference until we changed our beds. Mosquito bites go off in a couple of days but bed bugs stays and become reddish. Voted up

    • vocalcoach profile image

      Audrey Hunt 4 years ago from Nashville Tn.

      Good information about mosquito bites versus bedbug bites. The photos are a major help. Voted up and sharing.

    • NC4Life078 profile image

      NC4Life078 4 years ago from United States of America

      Very useful information, I commend your article for being on the first page of Google. It made me laugh when I clicked on the link and brought me to hub pages.

    • profile image

      terrified 5 years ago

      I have a rash that looks identical to the ones you show. Ihave no other signs at all. No faecal traces or evidence on my bedding. I'm really scared.

    • teaches12345 profile image

      Dianna Mendez 5 years ago

      This is a good description and comparison on bug bites to poison ivy and mosquito bites. I can see the difference. Thanks for sharing.

    • nochance profile image

      Chloe Davis Smith 5 years ago from Minnesota

      I had a roommate in college who woke up one day with a mysterious rash. First health services told her she had scabies, then they thought there were bedbugs in our room even though I didn't have a rash so we got to spend three days in a different building while our room was checked. Then they finally discovered she had a gluten allergy. She had consumed a large amount of beer at a party the night before.

      So knowing how different sorts of rashes appear is very useful to know. Great hub with some great pictures.