Mosquitoes

Mosquitoes are a water problem before they are a spraying problem. However many adults you knock down on a summer evening, a bucket in the yard, a blocked gutter or a forgotten plant pot saucer replaces them shortly afterwards. Only the females take blood; the males feed on plant juices. A lasting reduction is won where the water stands, not where the biting happens.

How to recognise them

What separates a mosquito from other flies of the same size is the long slender proboscis, adapted for piercing skin and drawing blood. Around buildings, two groups account for most of what people meet.

Culex mosquitoes are the plain grey-brown ones that breed in the stagnant water around a property. Aedes albopictus — the Asian tiger mosquito — can be told apart on sight: a black body carrying white and silver scale patches, with a single silver line running down the middle of the scutum, which is the diagnostic mark. The ECDC records that its females bite aggressively, usually during the day and by preference outdoors, and that they breed in artificial containers — tyres, barrels, rainwater gully catch basins, drinking troughs. The species has spread across much of southern and central Europe; which species is present in a given area is a matter for local surveillance.

It starts in the water

Water held in something no bigger than a bottle cap is enough to carry larvae, and eggs laid on the surface can hatch within a couple of days. A garden therefore rebuilds its mosquito production in days, not weeks.

The WHO advice to households is straightforward — remove artificial habitats that hold water, and cover, empty and clean domestic water storage containers weekly. On a real site that means:

• Pot saucers, buckets, tubs, bin lids, folds in tarpaulins, scrap tyres
• Bird baths and pet bowls — change the water weekly
• Roof gutters and rainwater gullies — keep them running clear
• Water butts and tanks — lidded, or screened with fine mesh

What it means for health

The WHO puts vector-borne diseases at more than 17% of all infectious diseases worldwide, causing over 700,000 deaths a year. Aedes species are the group that transmits chikungunya, dengue, lymphatic filariasis, Rift Valley fever, yellow fever and Zika; Culex species transmit Japanese encephalitis, lymphatic filariasis and West Nile fever.

Which of those occur depends on the region, and the presence of a mosquito does not mean the presence of the disease. Itching, swelling or any allergic reaction after a bite is a matter for your doctor.

How the treatment works

The work begins with a survey of the building and the ground around it, listing every point that holds water: basement and lift-pit seepage, gullies and catch basins, ornamental ponds, roof gutters, tanks and butts, low spots in the planting.

Anything that can be drained is drained. Standing water that cannot be drained is larvicided, using products based on Bacillus thuringiensis israelensis (Bti). Adult treatment is the supplementary step: residual surface treatment on resting surfaces, and ULV fogging outdoors where numbers are high. Fogging drops the mosquitoes flying at that moment and does nothing to the larvae in the water, which is why it is never used on its own. We work with biocidal products licensed by the Turkish Ministry of Health, and keep monitoring the breeding points afterwards.

What you can do

Fit screens to windows and doors, and repair the torn ones. WHO personal protection advice is clothing that covers as much of the body as possible, together with repellents containing DEET, picaridin or IR3535. Follow the directions on the product label, and ask your doctor about use on children.

In blocks and gated developments, one flat acting alone rarely gets far. If the water sitting in the gardens, communal areas and car park is left as it is, even a well-screened flat shares the same source.