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The majority of insects in Australia are not harmful to humans. However, some insects bite and sting if they are threatened so it is best to avoid touching them if you want to avoid being stung or bitten.
Some people are allergic to certain insect bites or venom. In the case of an allergic reaction to bites or stings, medical attention should be sought. Call a doctor or hospital for guidance.
The Australia-wide Poisons Information Centres have a common telephone number: 131 126.
Common biting or stinging insects
Common insects that bite or sting:
- Bed Bugs
- Honey Bees
- European Wasps
- Biting and non-biting flies
- Head Lice
Other biting or stinging arthropods
Two species of bed bug occur in Australia, Cimex lectularis and Cimex hemipterus. Bed bugs are relatively small insects, about 5 mm in size. The body is dorsoventrally (from back to front) flattened and they have no wings. They have obvious eyes and sucking mouthparts, and are reddish brown in colour. Bed bugs are blood feeders and are most active at night or in the early hours before dawn, but if starved for some time they may be active during the day.
To obtain a blood meal the bed bug pierces the skin of the host and injects saliva. This saliva has anticoagulant properties which makes the blood flow more easily. Bed bugs ingest their meal rapidly only taking 5-10 minutes to engorge themselves. A blood meal is required at each of the five stages of nymphal development. Female bed bugs lay several eggs in small batches, which hatch in about 10 days. Adult bed bugs can live for approximately 6-12 months. Because of their size bed bugs can get into small cracks and crevices.
Reactions to bed bug bites can vary from no reaction at all to severe irritation and localised swelling at the bite site.
Honey Bee, Apis mellifera, stings are barbed and, when a person is stung, the sting (with venom gland attached) will stick in the skin and tear away from the bee. This injury kills the bee, but the venom gland continues to pump venom through the sting, so it should be removed as soon as possible. Do not squeeze it as this will force more venom into the wound. The sting is best removed by scraping it out with a fingernail.
Most Honey Bee stings cause intense local pain and swelling. However, if a victim is allergic to bee venom, a sting may cause more general symptoms. Most seriously, these can include difficulty breathing and collapse. If a sting victim is known to be allergic to wasp and bee venom, medical attention should be sought immediately.
If you find a swarm of bees, do not approach it. Contact your local beekeepers' association or look up under 'Bee and Wasp Removal' in the Yellow Pages.
European Wasps, Vespula germanica, are more aggressive than bees and will attack when their nests are disturbed. Unlike bees, wasps can sting more than once and do not die after stinging. The sting causes a burning pain and swelling. Ice or cold water should be used to relieve the pain. If a sting victim is known to be allergic to wasp and bee venom, medical attention should be sought immediately.
Biting and non-biting flies
Some biting and non-biting flies can cause problems at certain times of the year. A housefly can carry millions of bacteria in its gut, mouthparts or on its feet.
Scientists have tried introducing various other insects as a means to control fly numbers. For example, dung beetles have successfully been introduced in Australia in areas where high amounts of cow dung have increased fly populations. The dung beetles use cow dung as their food and shelter, breaking up pats of cow dung quickly before fly populations can take hold.
Mosquitoes are also biting flies. They can carry diseases such as malaria. This disease is passed on to humans from the mosquito's salivary glands into their human host's bloodstream. In Australia, malaria is not a major health problem, but other mosquito-borne diseases such as Ross River Virus and Murray Valley Encephalitis are of increasing concern.
Head lice, Pediculus capitis, are blood-sucking ectoparasites of humans. This common human parasite does not affect other animals.
An adult head louse is a small six legged insect, 2.5 mm - 3.5 mm in length, with well developed eyes, small antennae and a flattened light brown body. The claws on each leg enable the lice to hold on to hairs, and they can run quickly over the scalp through hair. Head lice live their entire life (about a month) on the head of their host, and are often concentrated towards the back of the head and above or behind the ears.
Head lice suck blood from the surface of the scalp and can feed at any time of the day or night. Without a human host, head lice will only survive a few days. They cannot infest furniture, bedding, pets or other household items.
Transfer of head lice to individuals is most commonly by hair to hair, head to head and close bodily contact. Sharing combs, brushes, ribbons, hair bands, hats, pillows and similar personal articles is another way that lice can spread.
Several species of ants pose serious health threats to people sensitive to their stings, notably species of Myrmecia (the bull ants and jack-jumpers) and Odontomachus. In extreme cases hospitalisation may be required. There is anecdotal evidence from bush workers that repeated exposure to stings over several years can result in increased sensitivity to the venom. If a sting victim is known to be allergic to wasp and bee venom, medical attention should be sought immediately.
Not all ants have stings.
Ants from the subfamilies Ponerinae (Green Head ants and others), Myrmeciinae (Bulldog ants, Jack Jumpers), and Myrmicinae (includes the introduced Fire ant) all have functional stings. However, many of the most common ants such as the Dolichoderinae (Meat ants, Coconut ants, Argentine ants) and Formicinae (Sugar ants, Green Tree ants) do not have functional stings, and rely on spraying noxious chemicals at potential threats.
For medical information about all of these biting and stinging insects (and other arthropods), the Department of Medical Entomology at the University of Sydney has a series of fact sheets on Medically Important Arthropods that assist with identification and treatment.