Been Bitten By Something? Here's How To Tell What Did It


Robin Andrews

Science & Policy Writer

A close-up of a mosquito's head. Macroscopic Solutions via Wellcome Collection

Ignoring the occasionally deadly temperature extremes that are ravaging the planet right now, from Scandinavia to Japan, summer for many of those reading this article is a joyous time, full of sunny weather and outdoors marvelousness. For others, it’s a time to lather on the anti-mosquito soup, for the bitey bastards are out in force.

You don’t often notice when you’ve been bitten, but a casual, lighthearted itch turns into a lump-discovering scratch. These can range from the irritating and a little tingly to serious miniature mountains of medical woe on your person.


If you’re worried about a bug or insect bite, you should go to a medical professional as soon as possible – but for those just a little curious as to what they may have been feasted on by, here’s a rough guide for those in Europe and North America.

Some of them are seasonal to a degree, like mosquitos and mites, but others can appear all year round. For more detailed medical information, check out the UK’s National Health Service (NHS) site, the US National Library of Medicine’s MedlinePlus directory, and any clinical professional.

Mosquito Bites

Although known to be one of the biggest killers around today in certain parts of the world – through their ability to spread malaria – they aren’t such a concern in the UK and the US, with some exceptions. Remember, if you’re feeling very ill after a mosquito bite, seek medical attention tout suite.


When bitten by one, the action of the needle-like apparatus designed to both drink your blood and stop it from coagulating ultimately causes small, red, raised points on your skin. In some instances, people may develop grosser, fluid-filled blisters.

Classic mosquito bites. Jane Shemilt/Science Photo Library

Horsefly Bites

As with mosquitoes, only the females here have the need – and biological capability – of piercing through your skin and performing their unbelievably frustrating act of vampirism-in-miniature. As explained by the Natural History Museum (NHM), blood is required to make eggs, so males don’t bite.

A type of horsefly. MegSopki/Shutterstock

Unlike mosquitos, though, horseflies are less sneaky and more brazen. Instead of injecting you with a painkiller in order to stealthily get their drink on, horseflies don’t – they just bite you, resulting in some excruciating incidents. Although in some cases, you can be allergic to these bites and experience dizziness, a rash, wheezing, and swelling, most people will see a raised, red hill appear post-encounter.

An allergic reaction to a horsefly bite. Dr P. Marazzi/Science Photo Library

Bedbug Bites

The stuff of nightmares: These oval-shaped beasties can sometimes give people an allergic reaction when bitten, but they’re mainly just horrific, bloodsucking metaphors for life in general. Seeing tiny dots scoot around your mattress, or the dried defecations they leave on your pillow, would give anyone cause for grief.

A scanning electron micrograph (SEM) image, digitally colorized, of a certain species of bedbug. CDC

If they decide that you’re dinner, you may get very small red bumps – particularly on your neck, hands, arms, or (ugh) face. As noted by the NHS, they often occur in straight lines, because they clearly went to the Prometheus school of running away from things.

Bedbug bites. James Heilman, MD/Wikimedia Commons; CC BY-SA 3.0

Mite Bites


There are far too many types of mite to have to think about; house dust, furniture, flour, bird, harvest, and red spider mites, to name just a few. They all behave a little differently, but their modus operandi is the same as all the other monsters on this list: they’re hungry for your blood.

The human scabies mite, magnified here 20x by an optical microscope. Arthur Goldstein/Wikimedia Commons; CC BY-SA 4.0

As ever, red lumps will appear, but these tend to be itchier than those you’d get from other insects. You can sometimes get blisters or a rash.

Bite marks left by chiggers, types of mites. Tim Vickers/Wikimedia Commons; Public Domain

If you’re unlucky, however, the mites may bury down beneath your skin, lay eggs, and cause scabies, a highly infectious condition that just needs brief skin-to-skin contact.

Scabies. Wikimedia Commons/Public Domain

Now, anyone can get scabies – it’s not all about bad hygiene. If you think you have it, see a GP, and wash all your clothing and bedding on a high-heat cycle.


Tick Bites

As noted by MedlinePlus, these critters hang around in fields and amongst vegetation, jumping onto you as you brush past them. They then migrate to warm, moist places on your body – yes, there – before grabbing onto your hair and drinking some of your crimson nectar.

Ticks stay on you for quite some time, so you don't have to play the guessing game for long. Aksenova Natalya/Shutterstock


There are, rather awfully, over 850 types of ticks, and many can spread diseases, including Lyme disease and Rocky Mountain spotted fever. Some can make you allergic to red meat for the rest of your life, and others can cause paralysis in children.

A "bull's-eye" rash at the site of a tick bite. The patient subsequently contracted Lyme disease. CDC/James Gathany

Again, raised red bumps are the order of the day, which will not initially be painful but can become vexingly itchy. Get any other symptoms that cause you concern, though – like breathing difficulties, a rash, severe pain, or motor control malfunctioning – go see a doctor straight away.

Spider Bites

Like ticks, there are so many types of spiders, from the large to small, the aggressive to the shier, the venomous to the harmless. Bite marks will vary wildly depending on what part of the world you’re in and what eight-legged beastie you’ve pissed off, but here are a few common ones to look out for.

A brown recluse spider, armed with a necrotic bite, is commonly found in the southeastern US. Br-recluse-guy/Wikimedia Commons;Public Domain


The bite mark from a brown recluse spider. CDC
A female Northern Black Widow spider (right) - armed with a toxic bite - is often found throughout the eastern US. Marshal Hedin/Flickr via Wikimedia Commons; CC BY 2.0
A black widow spider bite. Maximuss20722/Wikimedia Commons; Public Domain
A female wolf spider, common in Europe, the US, and beyond. Patrick Edwin Moran/Wikimedia Commons; CC BY-SA 3.0
A wolf spider bite a few days post-event. Domain

As elucidated by the US Centers for Disease Control and Prevention (CDC), the symptoms of spider bites are extremely varied and can include itching, a rash, pain at the bite site, muscle cramping or pain, increased sweating, swollen lymph glands, nausea, vomiting, fever, chills, high blood pressure, anxiety, and more.

Having these symptoms doesn’t mean you have been bitten by a spider, but you get the mantra by now. Worried? Go to see a GP.

Flea Bites

Again, they’re small, red, raised bumps. Sorry that’s just how most of these allergic reactions go – but in this case, they often appear around the ankles and legs. If you live or work around livestock, have a rodent cohabitation problem, or have dogs and cats, you’re more likely to meet them, in a manner of speaking.

A typical dog flea. Luis Fernandez Garcia/Wikimedia Commons; CC BY-SA 2.5 es

Grimly, this site explains that children under 10 are more sensitive to such bites, and in some cases, fleas focus on one individual in the household. If you’re hypersensitive, you can get a rash, and maybe even long-term symptoms that take years to fade away.

Flea bites on a young girl who's fairly allergic to them. Dr P. Marazzi/Science Photo Library

Fire Ants

Bit of a bonus round here, as these sting rather than "bite".

A small minority of those belonging to the genus Solenopsis – all 200 species of the stinging nasties – are known as fire ants. Although the moniker has widespread use, it’s most accurately used to describe those that are not native to the US, but instead hail from parts of South America, like Argentina and Brazil.

A member of the Solenopsis genus. CSIRO/Wikimedia Commons; CC BY 3.0

They’re not just known for their raft-building abilities – deployed during floods and to cross rivers – but their stings, which are obviously not vampiric, but instead aggressive/defensive in nature. They deliver venom into your skin, which cause burning, itching, and raised red lumps. This can sometimes produce a painful lesion, and if stung a lot, it can cause a dangerous toxic reaction.

Fire ant stings/bites seen after 24 hours. Scott Camazine/Science Photo Library


  • tag
  • europe,

  • Canada,

  • images,

  • identification,

  • bites,

  • US,

  • bumps,

  • rough guide