Mosquito, Bed Bug, Spider Bite Differences

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

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

Mosquito Bite
Bed Bug Bite
Spider Bite
Raised welts that appear randomly on the body
Flat red dots that come in groups of three due to bed bug feeding habits
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

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.

Identifying Bites and Rashes

It can be difficult to tell the difference between different kinds of bug and insect bites, not to mention fungal rashes, allergic reactions, and poison oak and ivy.

Symptoms of mosquito bites, bed bugs, and allergic reactions can look very similar, though there are some characteristic differences. Below, you will find pictures to help you tell the difference.

You can't make an accurate determination of what bit you merely by looking at the bite. When doctors examine a rash, they explore many factors to determine the source.

To figure out what bit you, you should ask yourself:

  • Where did I get the bite (in what environment and where on my body)?
  • Where might I have been exposed: Have I been outside or spending time at others' homes?
  • Does my home show any signs of infestation?
  • How long has the rash lasted?

The answers to these questions can help you determine the culprit.

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

In Detail: Mosquitos vs. Bed Bugs

Mosquito and bed bug bites can cause cause allergic reactions. They may appear immediately after exposure or later, as body chemistry affects the timing of the reaction.

Only your doctor can tell you what your rash is, and even they might have difficulty identifying it. The key to identifying your rash is thinking like your doctor and asking all the questions below, but you'll still need to see your doctor to be sure.

Mosquito Bites

Mosquito bites tend to appear in isolation. If you have only one or two, it's probably not bed bugs. Also, since these bites itch, they may appear red and inflamed, but this is caused by your scratching fingernails.

The size of the bite depends on the person, the size of the mosquito, and length of time the mosquito bit. However, the bites can get quite large. Unlike with 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 (appears lighter than the surrounding skin).
  • The area around the bite may appear red.
  • Initially soft bump (that may turn hard with scratching).
  • Bump may turn red.
  • Itchiness.

If you look at the bump and still can't tell, you should 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 your sheets? (These may be bloody signs of bed bug bites.)

Bed Bug Bites

Bed bug bites are never white. They are even, flat bites which are reddish in color. Mosquito bites resolve themselves faster than bed bug bites, so if the bites linger for weeks, you might have bed bugs.

They tend to appear in clusters. Sometimes, they don't look like bites or a rash at all, but instead look like a bunch of welts. Bed bugs hang out together and keep biting, so their bites appear in groups, and the location of the bites on your body can give you a good clue about where to look for signs of the bugs themselves. For example, if you sleep on your back on the left side of the bed and you have a line of bites down your left thigh, check the mattress there.

You cannot identify these bites by sight alone. You can only use pictures as a guideline. If I said anything else, bed bug experts would wallop me! If you look at the bumps and still can't be sure, you'll want to check for visual evidence of a bed bug infestation.

Look for a live cluster of bed bugs, dead bugs, discarded exoskeletons, or bug feces (rusty-looking stains). Check your bed, your furniture, and even your car.

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 Is Worse?

Mosquitoes are far more dangerous than bed bugs because they transmit diseases such as malaria, West Nile Virus and Zika.

Bed bugs are not known to spread disease. Scientists thoroughly monitor bed bug epidemiology, and if they learn anything different, they will tell us.

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. An exception to this rule is people who are allergic to mosquito bites, who can have disturbingly large and painful welts that last much longer.


You're best off preventing bed bugs in order to keep them from biting you. If you suspect you have a bed bug infestation, you should take action immediately since the longer you wait, the harder (and more expensive) it will be to get rid of them.

Many people pick up bed bugs at hotels or while staying in other peoples' homes. To keep unwanted travelers from returning with you, you should inspect the bed and mattress of a hotel carefully.

If you get bitten by what you think is a bed bug, when you get home you should unpack your suitcase outside of your home and carefully put clothes through a hot wash and dry cycle. Take steps to dis-infest your suitcase too.

Poison Oak or Poison Ivy Rash vs. Bed Bugs

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

Bed bugs and poison oak/ivy have little in common, but a serious bed bug reaction can look like a poison ivy/oak rash.

Both types of rashes can have the same reddish coloring and they can both appear as a cluster of raised welts. However, bed bug bites do not usually cause blisters the way poison ivy does.

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

Spiders vs. Bed Bugs

Because there are so many different spiders (more than 20,000 different types 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 can take longer to heal than other bites, and may affect skin tissues. It is important to keep the bite clean to reduce the risk of infection. Also, 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, stomach upset (nausea, vomiting), heavy sweating, drooling, headaches, rapid heart rate, changes in blood pressure, muscle pain, anxiety, swollen lymph glands, or difficulty breathing, 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?

  • Bed Bugs
  • Mosquito
  • Spider
  • Poison Ivy / Oak
  • Other (please explain in the comments section below!)
See results without voting

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.

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

Comments 25 comments

Random 2 weeks ago

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

Bedbugabscond profile image

Bedbugabscond 6 weeks ago from United States Author

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!

Karinethemom 6 weeks 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.

That Guy 6 weeks ago

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

Colleen 7 weeks ago

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

Cat 2 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.

susan 3 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!

Sara 4 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.

Richard 7 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

Bite me 12 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)?

Hello 15 months 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.

Me 16 months 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!

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bethperry 2 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.

areniomma 2 years ago

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KenDeanAgudo 3 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 3 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

Bedbugabscond 3 years ago from United States Author

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

epbooks 3 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!

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mercuryservices 3 years ago from Honolulu, Hawaii

Don't let the bed bugs bite.

peachpurple profile image

peachpurple 3 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

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vocalcoach 3 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.

terrified 4 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

teaches12345 4 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

nochance 4 years ago from Duluth, MN

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.

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    Melody Trent (Bedbugabscond)135 Followers
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    Melody is a CDC Committee volunteer and activist who has been fighting and educating others about bed bug infestations for years.

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