inhabit every corner of the globe and there are perhaps
more species of insect than all the others put together. They
are remarkably successful creatures and have adapted to survive
in just about every environment.
species of insects are parasitic, living off a host rather
than devouring it. Part
of their success is this ability to prey off other species,
Biting insects such as mosquitoes
and sandflies cause much inconvenience due to local reactions
to the bites themselves which are rarely harmful, but in doing so they can spread diseases some
of which are potentially fatal.
will bite at any time of day but most bites occur in the
evening so extra vigilance is necessary after sunset.
Other insects like bees,
wasps and ants posses stings which can be quite painful and
sometimes dangerous. Hundreds of stings by bees or wasps can
be fatal due to direct toxicity.
There are dozens of insects whose bites or stings cause
problems, and they can be split into two categories: venomous
and non-venomous. The tables below explain the main differences.
Difference Between Bites and Stings
The difference is
due to the nature of the bite or sting. Venomous insects attack
as a defence mechanism, injecting painful, toxic venom through
their stings. Non-venomous insects bite in order to feed on
your blood. Although local irritation and allergic reactions
to the saliva and anti-coagulants do occur from non-venomous
bites, severe reactions such as anaphylactic shock only happen
from venomous stings.
When bees sting, they leave the
sting and venom sack attached. Venom continues to pump in
through the stinger until the sack is empty or the sting is
removed. The only good part about this is that bees die after
they sting. Wasps and hornets however, don't leave their stings
behind and can sting you over and over.
Can be intense
Mild or absent
Venomous stings are always very
painful, red, and swollen up to twelve inches around the sting
site. This is called a local reaction. In sensitive individuals,
a systemic or "whole body" reaction occurs, with redness,
hives (itchy raised skin lumps), and swelling far away from
the sting site. These systemic reactions can be life threatening
and it is important to know the difference between them.
people with a known allergy to the stings should carry an
emergency syringe with 0.1% adrenaline and know how to use
Biting insects themselves, aren't
generally dangerous because allergic reactions are rare. They
do however, spread diseases like Malaria, Yellow Fever, Lyme
disease, Typhus, and Encephalitis, but for most of us their
bites just cause terrible itching.
Against Insect Bites
The occurrence of mosquito and other insect bites
can be minimised by wearing long-sleeved shirts, long pants,
and hats to reduce exposed skin. Repellents applied to clothing,
shoes, tents, mosquito nets, and other gear will enhance protection.
Bednets provide protection and comfort when accommodations
are not adequately screened or air-conditioned. Bednets should
be tucked under mattresses and can be sprayed with repellent.
Aerosol insecticides and mosquito coils may help to clear
rooms of mosquitos; however, some coils contain DDT and should
be used with caution.
Tucking shirts into pants and pants
into socks will increase protection. Boots also decrease the
risk of bites. During outdoor activities and at the end of
the day, travellers should inspect themselves and their clothing
for ticks. Prompt removal of ticks may prevent infection.
These tips are also helpful in answering the question to how
to get rid of bed bugs that are devouring you at night.
Repellents containing DEET (N, N-diethylmeta-toluamide)
are commonly available and effective against mosquitos, ticks,
and other arthropods when applied to skin or clothing. Repellents
with DEET concentrations of about 30% are quite effective
and should last for about four hours. The possibility of adverse
reactions to repellents can be decreased by taking the following
- Apply repellents sparingly
only to exposed skin or clothing
high concentrations of DEET
- Do not inhale, ingest,
or get into the eye
- Never use on wounds
or irritated skin
- Wash repellent-treated
skin after coming indoors
- Pregnant and nursing
women should minimise use
- Avoid applying to children's
hands that are likely to have contact with eyes or
- For more information
on DEET go to DEET.COM
- To view a video
presentation by the Malaria Awareness Campaign about
the need for proper protection from insect bites whilst
travelling abroad, click on the image:-
is a 100% natural midge and mosquito repellent and an
alternative to DEET for those who cannot tolerate it.
plant oils, MozzyOff offers you up to six hours protection
from biting insects such as midges and mosquitoes, black fly
and gnats. It's water resistant and unlike chemical based
products, MozzyOff repellent will not harm synthetic materials.
MozzyOff is also biodegradable and the packaging is recycled
and recyclable so its good news for the environment too.
is kind to your skin and its inherent soothing properties
mean that it will relieve the itch of previous bites and hopefully
stop you getting bitten again. For further information see
Permethrin is also a highly effective
repellent and insecticide for use on clothing, shoes,
bednets, and camping gear. Permethrin-treated clothing repels
and kills ticks, mosquitos, and other arthropods and retains
this effect after repeated laundering.
yourself and your kids from mosquito
bites as well as ticks and other harmful insects, with Permethrin
Impegnated Insect Repellent Clothing. Click the graphic to
browse the web site:-
Itching is the main symptom to control with insect bites.
Topical antihistamines and anaesthetics are for quick temporary
relief; hydrocortisone cream has slower onset, but longer
- Ibuprofen Gel. For pain and swelling
from insect stings, is an excellent anti-inflammatory with
- Hydrocortisone cream 1% This
preparation improves both itching and swelling/redness.
It actually has anti-inflammatory effects, not just symptomatic
relief like the topical anaesthetics. However, it does take
longer for full effect than topical anaesthetics.
- Xylocaine Gel 2% For immediate
relief from surface itching and pain.
Any systemic reaction should be
seen by a doctor immediately. This includes hives wherever
they may occur, swelling in the face, shortness of breath
or wheezing, difficulty swallowing, and light-headedness or
fainting. These usually occur within minutes to an hour after
Local reactions generally don't
require professional care. However, if your local reaction
causes enough swelling or pain to distract you from your normal
activities or keep you awake despite basic treatment, you
should see a doctor. If the redness/swelling is worsening
after 24 hours, see your doctor.
First, the stinger must be removed. Pain, swelling, and
itching are the main complaints. Home remedies include baking
soda or meat tenderiser compresses to "draw out" or destroy
protein-based venom. Scientific data is lacking with these
techniques, but they do make logical sense. See the table
below for medications which can help.
Place the edge of a dull table knife firmly against your skin next
to the embedded stinger. Applying constant firm pressure,
scrape the knife across your skin surface and the stinger.
This removes the stinger without injecting more venom, which
is what happens when you remove the stinger with tweezers
or your fingers.
are the familiar flying insects, (family Culicidae), numbering
about 2,500 species, that are important in public health because
of the bloodsucking habits of the females.
are particularly dangerous
insects since they are known
to transmit such serious diseases as yellow fever, malaria,
filariasis dengue and Japanese
B encephalitis. They bite at any time of day but mostly in
species of mosquitoes show preferences and, in many cases,
narrow restrictions as to host animals. They are apparently
attracted to host animals by moisture, lactic acid, carbon
dioxide, body heat, and movement.
slender, elongated body of the adult is characterised by its
long, fragile-looking legs and its mouth-parts, which are
contained in an elongated proboscis. The threadlike antennae
of the male are generally bushier than those of the female.
and sometimes the females, feed on nectar and other plant
juices, but in most species the females require a blood meal
in order to mature their eggs, which are laid on the surface
hatch into aquatic larvae, which feed on algae and organic
debris; a few are predatory and may even feed on other mosquitoes.
The adults mate soon after emerging from their pupal cases.
The duration of the life cycle varies greatly depending on
three important mosquito genera:-
genus Anopheles the only known carrier of malaria, also
transmits filariasis and encephalitis. Anopheles mosquitoes
are easily recognised in their resting position, in which
the proboscis, head, and body are held on a straight line
to each other but at an angle to the surface. The life cycle
is from 18 days to several weeks.
genus Culex is a carrier of viral encephalitis, west nile
virus and, in tropical and subtropical climates, filariasis.
It holds its body parallel to the resting surface and its
proboscis is bent downward relative to the surface. The
life cycle, usually 10 to 14 days, may be longer in cold
genus Aedes transmits yellow fever, dengue, and encephalitis.
Like Culex, it holds its body parallel to the surface with
the proboscis bent down. The wings are uniformly coloured.
A.aegypti the carrier of yellow fever and dengue, has white
bands on its legs and spots on its abdomen and thorax. Aedes
usually breeds in floodwater, rain pools, or salt marshes,
the eggs being capable of withstanding long periods of dryness.
The life cycle may be as short as 10 days or as long as
facts about Mosquitoes
do mosquitoes bite?
Only female mosquitoes bite. Female mosquitoes require
a blood meal to acquire the protein needed to produce
eggs. Females lay multiple batches of eggs during their
lifespan, and a new blood meal is needed to produce each
batch. Different mosquito species prefer different host
species; some mosquitoes will seek blood meals from birds,
others from mammals - and some are generalists. The female
inserts her needle-like proboscis - a slender, tubular,
feeding and sucking organ - under the victim's skin, drawing
blood into her abdomen. She will feed until her abdomen
is full, unless discovered and brushed away.
Why do mosquitoes seem to bite some people, but not
others? This phenomenon is not completely understood.
Mosquitoes are attracted by the carbon dioxide that we
- and other animals - exhale. They may also be attracted
by various odors - perfume, perspiration, lactic acid,
detergents - that combine in unique ways to make one victim
more attractive than another as a meal. Because dark colors
absorb heat and lighter colors tend to reflect heat, mosquitoes
also tend to be more attracted to victims dressed in darker
clothes. Also, some people react more violently to the
bites than others and only appear to be bitten more often.
Why do mosquitoes bites itch and swell? The itching,
swelling, and burning from a mosquito bite are actually
caused by the body's autoimmune response to the saliva
injected by the mosquito when she feeds. This saliva contains
anti-coagulating agents that prevent the victim's blood
from clotting as it is sucked into the mosquito's abdomen.
A bite may take several days to heal and stop itching;
treat it with Calamine lotion or a topical anti-itch medication.
do mosquitoes breed? Mosquitoes breed in wet, swampy
areas, where they lay their eggs. The eggs hatch in the
water, and the young mosquitoes spend their pupal stages
in the water. Mosquitoes lay eggs in both fresh and polluted
water, and seek still waters such as those found in small
puddles, ditches, and ponds. Even a small amount of standing
water - say, in the bottom of a flower pot - will provide
sufficient habitat for mosquito eggs. These eggs usually
hatch about 5 days after they are laid. A key factor in
mosquito prevention is the elimination of standing water
in an area.
What is the average lifespan of a mosquito? Like
most insects, mosquitoes are a prime food source for birds,
amphibians, and spiders. Between predators and extreme
weather events such as drought and harsh rains, most mosquitoes
live for an average of about two weeks in their adult
form. If they manage to escape predators, females from
some mosquito species live to about two to three months
of age. Those females who enter adult form late in the
season may go into hibernation as cooler weather approaches,
and can emerge the following spring to lay eggs. In many
species, eggs laid before the onset of cold weather can
also survive through a winter, even without water, re-hydrating
in spring rains to go through larval, pupal, and adult
How many types of mosquitoes are there? According
to the American Mosquito Control Association, there are
more than 2500 species of mosquitoes world-wide.
These include any insect of the family
Phlebotomidae of the order Diptera. The aquatic larvae live
in the inter-tidal zone of coastal beaches, in mud, or in
wet organic debris.
The adults are often called biting midges and are only 2 to
3 mm in length making them difficult to see.
are found in almost any aquatic or semiaquatic habitat throughout
the world. Many of the blood-sucking species are pests in
beach or mountain habitats. They may also be vectors of disease-causing
viruses, protozoa, and filarial worms.
bite is not painful but often causes an allergic response
which becomes very itchy. Some people get a red weal 1-2 inches
wide! Avoid scratching the weals; it makes them itch longer
and can lead to infection.
flies are of considerable medical importance: around the Mediterranean
and in southern Asia, Phlebotomus transmits the pappataci
fever virus; and in parts of South America, Africa, and Asia
it carries the protozoan parasites causing kala azar, Oriental
sore, espundia, and bartonellosis.
sand fly is also used for certain species of the black fly
and the biting midge. They are often referred to as No-See-Ums
because you rarely see them.
Than Just an Irritation:-
Lurking on the beaches
of many of our favourite holiday and diving resorts is a disease
that can do more than just ruin your holiday.
It's a disease that can
haunt you for months after you return home, and even ruin
your life. Though it's not as widely known as malaria, it
can be every bit as painful, tenacious, and dangerous.
yet, the source of the infection is nearly invisible - the
ubiquitous no-see-um - the disease it transmits - Leishmaniasis.
If you've never heard
of leishmaniasis, you're hardly alone. The culprits that spread
the disease, commonly referred to as no-see-ums (because you
hardly ever see them), are minute insects of the genus Phlebotomus
often called "sand flies" and like mosquitoes, the gestating
female no-see-ums hungry for protein go in search of a "blood
meal". It is during the process of feeding that they transmit
the protozoan parasites responsible for the disease.
It is also possible for a fever
and rash to develop after receiving several no-see-um bites
as a reaction to the toxins in the bites themselves, and multiple
no-see-um bites can cause death from their toxins alone.
currently affects around 12 million people in 88 countries
(with 2.5 million new infections annually).
It is considered a dynamic disease whose range is constantly
spreading which is now well entrenched in the Mediterranean,
North Africa, The Middle East, South East Asia, Central America
and the Caribbean.
In its cutaneous form, leishmaniasis
is characterised by a skin sore or sores that develop weeks
or months after transmission. Sores typically leave scars,
and some forms can be severely disfiguring.
Visceral leishmaniasis, traditionally
known as kala-azar may take months and even years to develop
and is fatal if untreated. Symptoms include fever, weight
loss, cough, diarrhoea, lethargy, enlargement of the spleen
and liver, and anaemia. Both forms require a biopsy for diagnosis.
Though leishmaniasis only accounts
for a small percentage of tropical infections, unless the
victims consult physicians specialising in tropical medicine,
diagnosis is often inaccurate. The disease is quite difficult
to cure and victims are prone to recurrences.
decades the most effective treatment has been considered to
be sodium stibogluconate, but the three-week intravenous regimen
is relatively toxic, and the parasite is reportedly becoming
antimony-resistant in some areas so there is no guarantee
that it will not recur. Other treatments are available, but
no cure is 100% effective, and there are currently no vaccines
With no certain cure, prevention
is definitely the key. No-see-ums are usually more of a problem
at night and when the wind dies down on the beach. The first
line of defence is to cover yourself with insect repellents
containing DEET. Wear long-sleeved shirts, long trousers,
and socks in the evenings.
While the odds of bringing home
leishmaniasis are probably too small to allow it to influence
travel plans, the consequences of infection are so unpleasant
that it makes good sense to take aggressive steps to avoid
becoming the main course for a hoard of hungry no-see-ums.
If on return from an endemic
area, you develop persistent sores that you fear may be indicative
of leishmaniasis, ask for a referral to a tropical medicine
Tsetse flies can be anything from 7 to 15mm long. They are
sturdy flies not unlike houseflies and they have a painful
bite. They spread the disease known as sleeping sickness (Trypanosomiasis)
which is caused by a single celled motile organism. The disease
is serious and sometimes fatal and is difficult to treat.
There is no vaccine available. Sleeping sickness is thought
to be present in 36 countries of sub-Saharan Africa.
Tsetse flies require shade and humidity and tend to occur
along rivers and lake shores in association with game animals.
They are attracted to the scent of animals, movement and bright
Adult fleas are about 2mm long, wingless, and have three pairs
of legs. The hind pair of legs is modified for jumping. Fleas
are reddish-brown in colour and vertically flat like a fish,
and can move easily through the hair of a host. They feed
on the blood of their hosts.
wherever their host sleeps. Flea eggs are small and white.
The larvae of the flea look like small white worms with dark
heads. They live on the floor and feed on organic debris.
They form pupae which can lie dormant until they sense a suitable
host passing by and then they come out to feed.
human flea, (Pulex Irritans), is almost extinct in Europe
but other types of animal flea are much more common and will
bite humans especially when they cannot find their usual animal
host or if they become very numerous. Their bite often leaves
a small, red, irritated area.
tend to occur in groups, along clothing constrictions and
around the ankles. They often pass out undigested blood leaving
tell tale blood spots on bed sheets.
types of flea, especially rodent fleas, are able to transmit
diseases. Two of the more well known are endemic typhus and
plague. However these diseases are quite rare and confined
to the poorest areas of urban squalor.
fleas are endemic to Central America and West Africa. They
live outdoors in dry sandy locations. The female penetrates
the skin around the toes and then swells up with eggs causing
inflammation and ulceration. Gangrene can set in if left untreated.
Avoid going barefoot in areas known to be infested.
There are three types of louse that affect
humans; the head louse, the crab louse and the body (clothing)
louse. The head louse lives on the scalp, the crab louse lives
in pubic hair and sometimes arm pits and beards, and the body
louse infests clothing. They all feed by sucking the blood
of their host and they are spread by intimate contact or by
evidence of louse infection is the discovery of the tiny egg
cases called nits attached to body hair or clothing.
significant disease spread by lice is typhus which is spread
by body lice and is restricted to the very poorest areas.
Otherwise lice are merely a nuisance because of allergic reactions
and minor skin infections caused by their bites.
Travellers walking through dense undergrowth or exploring
caves may find ticks or mites attached to their skin but they
are relatively easy to remove with a pair of tweezers: grip
the tick firmly under the head end and push down to disengage
the "teeth" then gently pull away. Once the tick has been
removed, treat the bite area with antiseptic.
responsible for spreading diseases such as typhus, encephalitis
and lyme disease.
is caused by a small mite which burrows into the outer layers
of the skin and cause the characteristic itch which can be
almost unbearable but the mite does not carry any infectious
is caused by a small mite which burrows into the outer layers
of the skin and cause the characteristic itch which can be
almost unbearable but the mite does not carry any infectious
disease. In order to catch scabies it is necessary to be in
close contact with an infected person for some time. The itch
develops six to eight weeks after infection. Treatment consists
of applying an insecticidal lotion containing benzyl benzoate,
malathion or carbaryl.
of mite endemic to South East Asia can cause Relapsing Fever
which is a form of typhus.
and mites are actually arachnids and not insects.
bugs are oval shaped and flat, reddish-brown in colour and
can grow up to 10mm in length. They live in bed frames, cracks
in the wall, under wallpaper etc. and come out after dark
to feed when their victims are asleep.
do not carry any diseases but their bites can be very uncomfortable.
They tend to bite the face, arms and legs where they protrude
from the bedclothes.
South and Central America cone-nosed (assassin) bugs are common
in rural areas where housing standards are low. They can grow
up to 4cm in length with a thin head and long mouth parts.
They can transmit Chagas Disease (South American Trypanosomiasis)
which is a serious and sometimes fatal illness. Like bed bugs
they live in cracks in walls and come out at night to feed.
you are staying where either of these bugs are suspected,
move your bed well away from the wall and if possible leave
a light on in the room all night because they prefer to feed
in the dark.
Chiggers are the parasitic larvae of the harvest mite, Trombicula
alfreddugesi. The adults are harmless, but the tiny, six-legged
larval stage is parasitic on many animals, including rodents,
birds, rabbits, livestock, reptiles, toads, and humans. The
biting season is therefore limited to the late summer/early
autumn period when the larvae are active.
Chiggers occur in several parts of the world including the
southern United States and do not normally transmit disease.
However, in parts of Asia they are known to carry "scrub
are normally found in brush and tall grassy areas, especially
where small rodents are abundant. Females lay eggs on the
ground in groups of up to 400, picking damp but well drained
sites. They may be particularly abundant near river banks
and under trees or bushes.
The larval chigger is an active creature that moves to the
tip of grasses and fallen leaves to wait for and grab onto
a passing host. Once on its host, the chigger usually moves
about until it reaches a place where it is somewhat protected,
such as around ankles, under socks, waistline, under belts
and elastic bands of underwear etc.
Chiggers do not burrow into the skin, but they do pierce the
skin, (often around a hair follicle) and after secreting digestive
enzymes in their saliva, they suck up the liquefied host tissues.
The rash and intense itching associated with chigger bites
is an allergic reaction to their salivary secretions.
a larva is fully fed days, it drops off the host, leaving
a red welt with a white, hard central area on the skin that
itches severely and may later develop into dermatitis. Welts,
swelling, itching, or fever will usually develop three to
six hours after exposure and may last for weeks depending
upon the sensitivity of the individual. Scratching a bite
may break the skin, resulting in secondary infections.
Insect repellents containing DEET (diethyltoluamide) are effective
in repelling chiggers. For maximum effectiveness, repellents
should be applied to shoes, socks, pant cuffs, ankles and
legs, and around the waist. They move around the body for
several hours before feeding so bathing soon after exposure
to chigger-infested areas may wash the chiggers off your body
and prevent feeding. Take a good hot bath or shower and soap
Applying benzocaine cream, hydrocortisone cream or calamine
give temporary relief from the itching.
of Bites & Stings
are basically two types of prevention of insect bites and
Repellents and Avoidance
repellents work well for biting, non-venomous insects, but
not against angry stinging insects.
advertising claims, no oral products have ever been shown
to be effective insect repellents.
techniques for bites and stings are summarised in the tables
Avoiding Stinging Insects
wear perfume or scented lotions.
odours at picnics, garbage areas, etc.
brightly coloured clothing outdoors.
or relocate all known hives or nests near your home.
Mosquitoes, Chiggers, and Ticks
as much of your skin as possible with clothing, hats, socks,
special attention to cuff areas at ankles, wrists, and neck.
swamps (mosquitoes), dense woods, fields, and brush (ticks,
exposed skin and scalp areas for clinging ticks after returning
range of insect repellents and mosquito nets etc. can be obtained
on line from:-