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When the Asian tiger strikes

The Asian tiger mosquito (Aedes albopictus) is a small black and white mosquito, about ¼ inch long. It gets its name from its black and white striped legs and small black and white body.

The species was discovered in Malta in September 2009. For several years, it has been present in Italy, including Sicily, and considering the close proximity of the Maltese islands to Italy (and Sicily) and the large amount of sea traffic that occurs between Italy/Sicily and Malta it is not surprising that the species has now established itself here too.

It is an important pest species in urban areas and it also represents a high vectorial risk. Aedes albopictus is an aggressive biter with a high nuisance value and a known vector of at least 22 arboviruses. The most important of these are dangue, yellow fever, chikungunya, Japanese encephalitis and West Nile viruses. It also transmits dirofilariasis to dogs.

The reason why some people are bitten more than others remains uncertain and the most likely cause is due to our natural body smell, which the insect picks up.

Four or five days after feeding on blood, the female mosquito lays her eggs just above the surface of the water in a hard-sided container.

Male mosquitoes feed on plant juices and do not bite while the female species are aggressive daytime biters and prefer to bite outdoors. They feed on a wide variety of hosts including humans, domestic and wild animals, reptiles and birds but prefer mammalian blood. Most disperse less than 180 metres during their lifetime, so adults are never found far away from the larval habitats.

Peak emergence from diapausing autumn eggs normally occurs from mid-April.

Insecticides have only a limited effect on the mosquito. The control of Asian tiger mosquitoes begins with destroying the places where they lay their eggs, which are never far from where people are being bitten, since they are weak fliers, with only about a 180-metre lifetime flying radius.

Locating puddles that last more than three days and filling various items that can collect water with sand or fine gravel to prevent mosquitoes from laying their eggs in them would be a good start.

Any standing water in pools, catchment basins etc. that cannot be drained, or dumped, can be periodically treated with properly labelled insecticides or bacillus thuringiensis israelensis (Bti). Bti is a bacterium that produces toxins effective in killing larvae of mosquitoes while having almost no effect on other organisms.

Flowing water will not be a breeding spot.

The discovery of Asian tiger mosquitoes on the island has prompted some concern as to the nature of their vicious bite. Doctors recommend that a cold compress is initially applied to the affected area, followed by a topical antiseptic.

It is quite rare for mosquito bites to become infected and, so, for this reason, both topical or oral antibiotics should not be used unless there are obvious signs of infection.

Ronnie Galea is a pest management consultant.

Best ways to avoid infestations and bites

This particular mosquito bites mainly during the daylight hours, therefore, where possible, minimise areas of exposed skin during outdoor activities.

Insecticide aerosol dispensing units, vaporizing mats and mosquito coils can help to clear rooms of mosquitoes.

Optimum protection can be obtained by using repellents on exposed skin (products containing DEET).

Have secure screens on windows and doors.

Get rid of mosquito sources in your yard and garden by emptying standing water from flower pots, buckets, barrels etc. Change water in pet dishes every three days. Do not leave fish ponds without fish. Keep suitable fish in them such as goldfish.

Empty swimming poolsand wading pools when not in use, especially if the water is not chlorinated.

Locate puddles that last more than three days, inlets to sewers and drainage systems holding stagnant water and drain them.

Roof gutters should be kept clean of fallen leaves and other debris so that water does not collect in them.

Flower and plant pot under-plates that can collect water should be filled with sand or fine gravel to prevent mosquitoes from laying eggs in them.

Neighbourhood residents should work together to eliminate breeding sites like abandoned cars, old machinery and other junk in vacant areas.

Any standing water in pools, catchment basins, etc. that cannot be drained or dumped can be periodically treated with properly labelled insecticides or bacillus thuringiensis israelensis (Bti).

Trees and plants near the house, yard or garden provide shade and housing for mosquitoes and organic material, like leaves, give mosquitoes everything they need to breed and survive. Keep these areas free from accumulated organic debris.

Clean your gutters so the water can drain freely.

Treat the yard/garden area when necessary. An insect repellent sprayed on grass, shrubs and landscaped areas creates a barrier that insects won’t want to cross.

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