BITES AND STINGS
Insect bites and stings occur when an insect is agitated and seeks to defend itself through its natural defense mechanisms, or when an insect seeks to feed off the bitten person. Some insects inject formic acid, which can cause an immediate skin reaction often resulting in redness and swelling in the injured area. The sting from fire ants, bees, wasps and hornets are usually painful, and may stimulate a dangerous allergic reaction called anaphylaxis for at-risk patients, and some wasps can also have a powerful bite along with a sting. Bites from mosquitoes and fleas are more likely to cause itching than pain.
The skin reaction to insect bites and stings usually lasts for up to a few days. However, in some cases the local reaction can last for up to two years. These bites are sometimes misdiagnosed as other types of benign or cancerous lesions.
Insect bites often cause one or more red bumps that are usually itchy and sometimes painful. Often there's a small hole in the middle of the bite, perhaps with the end of the sting sticking out. Apart from this local irritation, the bite is not usually dangerous provided the victim is not allergic to insect bites.
Bee and wasp stings are more likely to cause allergic reactions than other kinds of insect bites.
WHAT ARE THE SOURCES OF INSECT BITES?
The sources of insect bites are recognised to be wide and varied.
Insects, such as fleas can be found on domestic pets, eg dogs and cats; and also on birds. Bedding and other soft furnishings around the house can also harbour bed bugs and fleas.
About 95 per cent of the fleas on a pet will be in the form of eggs, larvae and pupae (ie in the household) rather than on the animal. Simply working in your garden can expose you to fleas and other insects. Travelling can also put you at risk. Depending on your destination – exposure to mosquitoes, ticks and sandflies can occur.
WHICH INSECTS CAUSE STINGS OR BITES?
Stings or bites are caused by midges, gnats, horseflies, bees, wasps, ants, some spiders, fleas, lice, etc.
Wasp stings cause the most allergic reactions in the UK. One or more stings, over a period of time, may be required from a particular insect to sensitise your immune system and cause an allergic reaction.
Twenty per cent of people who have experienced an allergic reaction to an insect sting or bite will have milder or no reaction the next time they are stung or bitten by the same type of insect.
Therefore, it's impossible to predict the outcome of the next sting for any individual. If you're sensitised to wasp venom, it's unlikely that you'll suffer the same response to bee venom.
WHAT DOES A BITE LOOK LIKE?
There will be one or more swollen red bumps on the skin. In the middle, you will often see a small hole, which might have the insect's sting sticking out of it.
If you wake up in the middle of the night having noticed a painful or itchy lump, check to see if other parts of the body are affected. If there is only one bump, or four or five of them close together, you have probably been stung or bitten. Fleas often bite four or five times in the same area so you may find a couple of these clusters on your body.
Some children's diseases can also cause bumps and red, swollen skin. If in doubt, consult your doctor.
SYMPTOMS OF INSECT BITES
The skin becomes red, swollen, itchy and can be painful. These are the most common symptoms. Sometimes bites cause an allergic reaction. Bites can become infected by scratching. Look out for a rash or swelling that gets worse instead of better. If this happens, see a doctor.
Call your doctor immediately if you notice any of the following symptoms:
- the person has been stung by many insects at the same time
- a rash or swelling that gets worse instead of better
- if the site is red, tender and swollen
- nausea (feeling sick)
- pains in the chest
- choking or wheezing
- difficulty breathing.
HOW TO TREAT AN INSECT BITE OR STING
Remove the sting. Use tweezers to prise it out or scrape it off with your fingernail, or a credit card. Do not attempt to press out the sting, as this will only help the poison spread under the skin.
Wash the bite with soap and water, and then cool off the skin with ice cubes or an ice-pack that has been wrapped in a cloth or thin towel. Rest the affected area and elevate it if possible to prevent excessive swelling. Do this immediately after the victim has been stung.
If necessary, use a painkilling cream or gel or an antihistamine to soothe the itch. If you or a member of your family is allergic to insect bites, talk to your doctor or pharmacist before going on holiday. They may tell you to take an antihistamine with you in tablet form; or Adrenaline or as an EpiPen injection. If so, make sure you ask how to use them correctly.
Anyone who gets a rash or an itch requiring medical treatment, or who may simply feel unwell following a bite or sting should not drive, as there is a risk of passing out. If in doubt, consult your doctor.
Some hospitals provide an immunology or allergy clinic that may be able to confirm which venom an individual is sensitive to. This can be particularly useful if they have previously experienced an allergic reaction following a bite or a significant localised reaction with swelling of over 10cm diameter.
INSECT BITES AND ALLERGIES
People who are allergic to insect bites should carry a card, bracelet or necklace that lets other people know about their allergy. If the doctor has prescribed medication for you to be used in case of an allergic reaction, it is important that both you and your family know exactly how to use it.
HOW TO AVOID GETTING STUNG
- If surrounded by a swarm of bees or wasps, move out of the way slowly. Do not try to wave the insects away. Violent movements will only excite them and make them more aggressive and likely to attack.
- Insect repellents are effective.
- Never aim a blow at a wasps' or bees' nest or attempt to throw them because the insects will immediately attack.
- Stay away from things that attract insects, such as flowers, trees, bushes and piles of wood.
- Be extra careful if you are eating or drinking (especially sweet things) outside.
- Smells and bright colours attract insects. Avoid scented creams and strong perfumes if you are going to spend time outside.
- Long sleeves, long trousers, socks, shoes and gloves help protect you from stings.
- Close the windows in the house and the car to keep the insects out.
- Look out for insects' nests in your home or garden and have them removed immediately.
- Protective gear such as mesh covers for the face can be very effective against the nuisance of the highland midge in summer.
1. Allen, Arthur C. (March 1948). "Persistent "Insect Bites" (Dermal Eosinophilic Granulomas) Simulating Lymphoblastomas, Histiocytoses, and Squamous Cell Carcinomas". Am J Pathol. 24 (2): 367–387. PMC 1942711. PMID 18904647.
2. Goddard, Jerome (2002). Physician's guide to arthropods of medical importance. Boca Raton: CRC Press. pp. 14. ISBN 0-8493-1387-2.