Mild winter with virtually no snow and short-lasting frosts. It may seem that these are ideal conditions for the development of mosquito larvae.
"In fact, larvae of Anopheles mosquito develop in water at a temperature of about 4 degrees Celsius. However some of them, for example larvae of house mosquito, prefer warmer waters and develop at a temperature of about 10 degrees Celsius. Therefore a mild winter could contribute to the development of their population", says Andrzej Woźnica, an entomologist at the Agricultural University (Uniwersytet Przyrodniczy) of Wroclaw.
Wroclaw is surrounded by forests with small water reservoirs. Additionally, in Osobowice there are sewage farms. This is where spraying is carried out — to reduce the development of these nagging insects. In addition, the ponds are stocked all the time.
"We do our best so that the spraying is carried out in water. We use substances that are not harmful to the environment. We kill the larvae and then there is no need to repeat the spraying on large areas", says Monika Kaliwoda from the Department of Environment and Agriculture of Municipality of Wroclaw (Wydział Środowiska i Rolnictwa Urzędu Miejskiego Wrocławia).
The municipality of Wroclaw is monitoring the number of mosquitoes in the city. This year, on March 1, the companies will start checking the embankment of the Odra River, forests, parks and sewage farms. The locations of mosquitoes' concentration will be marked with GPS devices and spraying will be conducted there.
"The last year's monitoring shows that there are mosquitoes in the area of garden plots. It is a private land and we do not carry out spraying there. In addition, people collect rainwater and female mosquitoes lay eggs there. These places should be secured. We carried out an information campaign and gave out leaflets. The owners of garden plots took it seriously and the number of mosquitoes is decreasing", adds Monika Kaliwoda.
In 2013, the municipality has spent 630 thousand zlotys to fight with the mosquitoes. The officials claim that in the past year the increased rainfall and flooding of Bystrzyca area contributed to the development of mosquitoes.
"We are rather not threatened by the plague of mosquitoes this year", Andrzej Woźnica calms us down. "Spring is the main time for the development of mosquitoes. The increased rainfall, melting snow and high temperatures have a positive effect on the growth of their population, but this is not the end of the world, because when there are more insects, there are also more birds happy to feed on them", adds Dr Andrzej Woźnica.
It is worth to emphasise that you cannot annihilate mosquitoes completely, because they are an important part of the ecosystem. Fish and birds feed on them. Spraying and fighting with mosquitoes begins when the insects are nagging to the residents of the city.
Miłosz Turowski
