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Blood-sucking insects

Ctenocephalides felis (Cat flea)

Order: Siphonaptera

The most common flea encountered indoors is the cat flea. It doesn't particularly like feeding on humans but does try us out by biting in a number of places, often biting in a line along the waist where there is close body contact with clothes.

Family: Culicidae (mosquitoes)

Order: Diptera

Mosquitoes breed in stagnant water. The female mosquito requires a blood meal in order to have enough protein to lay eggs. Mosquitoes can carry various diseases, the most virulent in Africa being malaria which kills over 1.5 million people in Africa annually, most of them children. Fortunately, malaria does not occur in the Western Cape but nevertheless mosquitoes can be very troublesome and cause nights of bad sleep.

The following procedures are useful for preventing bites by mosquitoes:

  • use repellents on the skin such as Tabard - a mosquito will bite any exposed area that has no repellent on it so a dab here and there is not good enough;

  • if you are out in the open at night, e.g. round camp fire, dress to avoid being bitten, e.g. by wearing long pants. In malaria areas, it might even be worth treating the clothes with insecticides such as Peripell (active ingredient permethrin);

  • put gauze over windows that are opened at night;

  • use a bed net over your bed. These can be purchased from camping shops. Bed nets are much more effective if they are treated with an insecticide such as Peripell or Solfac (active ingredient cyfluthrin); and

  • kill mosquitoes in a room using mosquito coils, heated pyrethroid insecticide mats or a low-toxicity aerosol insecticide. Be careful not to overuse such products, as even the least harmful ones might affect you in unexpected ways.

If you are entering malaria areas, it is vital that you go out of your way to prevent being bitten and in addition take prophylactic drugs (consult your doctor on the right ones to take).

In the month following a visit to a malaria area, take any flu-like symptoms (temperature, sore muscles) extremely seriously and insist on being tested for malaria even if your doctor does not think it is malaria. Doctors that work in non-malaria areas can be very ignorant about this life-threatening disease.

Family: Psychodidae: Phlebotominae (sand flies)

Order: Diptera

Sand fly larvae inhabit places where there is high organic matter such as in animal burrows, termite hills and tree holes. Members of the genus Phlebotomus transmit trypanosome species in the genus Leishmania causing diseases collectively known as leishmaniasis.

 

Cimex lectularius (Bedbug)

Order: Hemiptera, Family: Cimicidae

Bedbugs hide in crevices in and near your bed by day and come out at night to suck blood. Despite being quite large (c 1 cm long), they often go undetected and large populations can build up in your bedroom before you find out what has been biting you. Bedbugs get into bedrooms by being carried there in crevices of secondhand furniture and pictures or in luggage infected in a bedbug-infested accommodation you stayed in previously.

To get rid of bedbugs:

  • remove mattress from bed and spray contact insecticide (e.g. Pick 'n Pay no name brand Surface Spray) in all nooks and crannies. If your spring mattress has holes in it, seriously consider buying a new mattress.

  • spray contact insecticide round legs of bed to prevent bugs crawling on to bed;

  • spray crevices in furniture and pictures near the bed if they are suspected to contain bedbugs; and

  • fumigate the room with e.g. Doom fogger.

 

 

Pediculus capitis (Head louse)

Order: Phthiraptera, Family: Pediculidae

Head lice occur on the scalp among your hair and their eggs (termed nits) are glued to the hair shaft. Children are often infected by head lice from their friends at school and this can cause great embarrassment and consternation to parents. There is no need to be embarrassed as having head lice as it is not a sign of poor hygiene - in fact they are particularly fond of clean hair and less fond of greasy, dirty hair.

 

Pediculus humanus (Body louse)

Order: Phthiraptera > Family: Pediculidae

Body lice are very similar in appearance to head lice but are found on the body rather than on the head. Body lice are associated with poor hygiene so people who bath regularly and wear clean clothes are unlikely to be plagued by these beasts.

 

Phthirus pubis (Pubic louse)

Order: Phthiraptera

Pubic lice or 'crabs' live in the pubic region, armpits and beards. They are usually transferred during sexual intercourse but on occasion can be transferred in unclean lavatories.

 

Family: Simuliidae (Blackflies)

Order: Diptera

Female blackflies feed on mammals and birds and can form large swarms that can be extremely troublesome. The larvae of black flies are filter feeders found attached to rocks at the bottom of rivers and streams.

 

Family: Ceratopogonidae (Biting midges)

Order: Diptera

Biting midges are among the smallest of the biting flies. Like mosquitoes, the female requires a blood meal in order to lay eggs. Victims include people, horses, cattle, sheep and poultry. There are two main genera found in southern Africa namely Culicoides and Leptoconops.

Genus: Culicoides

In these species, blood feeding takes place mainly during the night and the twilight hours. Eggs are laid on moist substrates such as cow dung or mud that has a high concentration of organic matter. Each female lays 100-200 eggs and under favourable conditions, a complete life cycle takes 3-4 weeks.

Genus: Leptoconops (Day-biting midges)

Unlike Culicoides, these midges feed mainly during the daytime. They are particularly troublesome in spring and form swarms round one's head, getting in and biting wherever possible. The main species responsible is Leptoconops kerteszi which in the Western Cape is particularly troublesome on the West Coast.

Life cycle

  • Fertilised females, after their blood meal, lay their 60-70 eggs in moist, salty sand (500-600 ppm salt) bordering saline ponds, streams or along beaches.

  • Egg development period is 10-12 days.

  • Larvae feed on organic matter near the surface of the moist sand over a long period of 8-10 months.

  • They pupate near the soil surface.

  • Adults emerge from the pupae, mainly in spring, and mate.

  • Females disperse 1-2 km in search of a blood meal.

Controlling these midges is difficult. Nothing seems very effective in preventing them from biting you. Drainage of breeding areas or using chemical control methods in the breeding areas can be helpful provided these are fairly localised which is not normally the case.

 

Family: Tabanidae (horseflies)

Order: Diptera

These are large biting flies that can be troublesome outdoors. Besides feeding on blood, many of them have long probosces used in sucking nectar from plants.

 

Stomoxys calcitrans (Stable fly)

Order: Diptera > Family: Muscidae

Stable flies look superficially like houseflies (they are in the same family) but instead of blunt, dabbing mouthparts, they have a sharp, rigid proboscis for blood-sucking. Larvae feed in decaying vegetable matter, often mixed with dung.

 

Family: Glossinidae (Tsetse flies)

Order: Diptera

Tsetse are found in tropical Africa and transmit sleeping sickness to humans and nagana to cattle.

 

Dermanyssus gallinae (Red poultry mite)

Class: Arachnida, Order: Acari

Mite are not insects but arachnids (they have 8 legs) but I include this species here because it is frequently a problem in homes and knowing about it can help solve the mystery bites you get in bed at night. The most common source of infestation is birds breeding in the roof and the mites are often erroneously referred to as bird lice. The mites move off the chicks in the nest and move down to the rooms below They bite only at night and hide away by day and can evidently survive without blood for up to five months. You can feel these mites biting you but seeing them is difficult because they are so small.

To kill the mites you need to fumigate (with e.g. Doom Fogger) the infested bedroom as well as the attic if there have been birds breeding there. The birds' nest needs to be removed and a way found to prevent them from breeding there again.

 

 Text by Hamish G. Robertson Blood-sucking insects


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