A sudden red and itchy lump on your skin is often a sign that an insect of some kind has had a feast on your body.
It can happen when you’re outside in nature or at home, and you may sometimes feel a small, sharp pain as it happens.
The most common offenders are mosquitoes, midges, ticks, horseflies, bedbugs, fleas, mites, ants and spiders -- and during the summer, most of these insects are out in greater numbers.
Why and how do insects bite?
Insects bite by piercing a hole into your skin to feed on your blood. When they do this, they release saliva that can cause the skin around the bite to become swollen, red and itchy.
Most insect bites are nothing to worry about and get better within a few hours or days, but they can sometimes cause an allergic reaction or even spread infectious diseases, such as malaria, dengue fever or Lyme disease.
The treatment for most insect bites is similar -- focusing on relieving itching or swelling -- but it can be useful to know what insect has bitten you to prevent further bites from happening and when you should worry.
Which insect has bitten you -- and what’s the impact?
Mosquito bites usually leave small, red lumps on your skin that are very itchy. Some people develop blisters filled with fluid.
But mosquitoes can also spread a wide range of infectious diseases through their bites, including malaria, dengue fever, Zika, chikungunya, and West Nile virus.
These conditions are more common across Asia, Africa and South America and occur less in North America or Europe. But some of them, like dengue and Zika, have transmitted locally in regions such as the south of France and Spain in recent years.
You should see a doctor immediately if you develop any of these symptoms following a mosquito bite:
- high temperature
- feeling sick
- muscle and joint pain
You may not feel a tick bite as they’re not always painful, but ticks can feed on your body for many days before dropping off. If you’re in an area that has ticks, it’s therefore important to check your skin -- and remove any ticks safely as soon as possible.
If a tick has bitten you, you may develop a small red lump and the area around the bite may become itchy, swollen or bruised. It may also form a blister.
Most tick bites heal within 3 weeks, but some bites can cause Lyme disease, depending on where you are. Lyme disease is more common in the forests of Asia, parts of Europe, and the US.
If Lyme disease is not treated, it can be serious, so you should see your doctor if you develop:
- a pink or red circular rash around the area of the bite
- a temperature of 38C (100.4F) or over
Bites from a horsefly can be very painful, as they cut your skin when biting you, rather than piercing it.
Bites can cause skin to become red and raised and may cause an infection. They also take a long time to heal. Other symptoms of horsefly bites include:
- a large red, raised rash (hives)
- parts of your body becoming puffy or swollen
If you have signs of an infection or the bites become more painful, red or swollen, you should see a doctor.
Midge or gnat bites
A midge is a small fly and its bites look similar to mosquito bites -- small, red lumps that can be painful or itchy, or both. Some people develop blisters from these bites.
Bedbugs live on furniture or bedding and their bites can be very itchy, but they don’t usually cause other health issues.
Bedbugs usually bite exposed areas of the body, such as your face, neck, arms or hands and you may see many bites in a straight line across your skin.
These bumps can be itchy and red and sometimes cause painful swelling. For some people, bites can result in a severe allergic reaction (anaphylaxis), but this is rare.
Mites are small insects that cause very itchy red lumps to develop after they bite you and these can become blisters.
They usually bite skin that’s not covered up, for example by clothing. But if the mites have come from your pet you may get bitten on your tummy or thighs -- if your pet’s been sitting on your lap.
Some mites burrow into your skin and cause scabies, which can then spread across your body.
Signs of scabies to look out for include:
- silvery lines on your skin with a dot at one end (where the mites have burrowed and laid eggs in your skin)
- a rash that soon spreads across your body, often starting between your fingers
- the rash turning into tiny red spots
If you think you have scabies, you should see a doctor immediately.
Fleas from animals such as cats and dogs often bite humans. Their bites can sometimes develop into blisters.
Like bedbugs, flea bites also cause small itchy red lumps grouped in lines or clusters, but the bites are often found below the knee -- usually around the ankles.
If you have a pet and carry them regularly, you may see bites on your arms.
Most spiders aren’t dangerous, but some are able to give you a painful bite.
Signs of a spider bite include a small puncture mark on your skin, redness, swelling and pain, but some bites can become infected and in rare cases cause a severe allergic reaction (anaphylaxis).
Severe symptoms include feeling sick, sweating, dizziness, nausea and vomiting. If you experience any severe symptoms you should see a doctor immediately.
Ants that bite humans include red ants, wood ants and flying ants.
Ant bites are usually harmless, leaving a pale pink mark on your skin. Sometimes the area can become painful, itchy or swollen.
If you experience any severe symptoms following any kind of insect bite, you should see a doctor. Otherwise, most bites go away on their own and any symptoms such as pain or itching can be treated with non-prescription creams, ointments or painkillers, such as paracetamol.