Let it be said, this summer, insects will be numerous in Belgium. Wasps, mosquitoes, flies and other critters risk punctuating the daily lives of Belgians. In question, a mild winter followed by good weather accompanied by the right amount of humidity.
The mildness of last winter is the first factor to explain a higher number of adult insects active this early summer. There were no significant frosts.
If there had been a period of several days with significant negative temperatures, for example a week with nights at -5 or -10 degrees, the adult insects would not have resisted. Only the larvae and eggs would remain. “Here, we are not at all in this scenario there. When we take mosquitoes, wasps, we have a whole series of insects which have resisted the winter and which are already there at the beginning of spring This is already a sign that we will have a summer with more insects “, explains Professor Frédéric Francis, head of the entomology laboratory at Gembloux Agro-Bio Tech.
Heat allows insects to reproduce faster
The warm spring that we experienced also played a role in accelerating the proliferation of insects. “The warmer it is, the shorter the cycles. We will increase the number of generations for a certain number of insects. If we take the case of the mosquito, a female will lay 20 or 30 eggs per day, per individual. cycle that will be shortened and, in addition to that, having a larger number of individuals who, in the next generation, will have the same reproductive capacities, this means that ultimately we have an exponential development of the number of individuals. In addition with the climate which remains favorable, with rather high temperatures, and now with optimal humidity for the cycle of insects, we have ideal conditions to have a development of insects “, continues Professor Frédéric Francis.
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With a temperature of 22 degrees, mosquitoes have a three-week cycle. If it is 30 degrees, the cycle time is reduced. For flies and wasps, the phenomenon is similar.
All the conditions are therefore met for a summer with more insects. News that the Belgians, who will be more likely to spend the months of July and August in Belgium because of the Covid-10, will have to put up with it.
More pests for crops
If aperitifs and meals on the terrace will probably be disturbed by the presence of wasps, if mosquitoes will disturb the evenings and nights of Belgians, the agriculture and horticulture sectors will also have to deal with the proliferation of insects pests. Aphids, beetles, weevils and other critters will be more present than normal. “If we take the case of pests like aphids, whose cycle is also dependent on the climate, we should expect to have a greater development, and therefore more pests. In aphids, we have very reproductive capacities important and exponential. So we know that this could cause significant problems “, explains Professor Frédéric Francis of Gembloux Agro-Bio Tech.
The box borer also benefits …
The boxwood moth is an Asian moth accidentally introduced to Europe in the 2000s. Since then, it has only grown. Present in southern Europe, it takes advantage of mild winters and hot summers to go north. Its presence has been established in Belgium for about three years. Today, with the warm spring that Belgium experienced, the box moths proliferate.
The caterpillars, green and black, of this butterfly are only interested in boxwood that they are able to devour in one night.
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When a boxwood is reached, it is difficult to save it. Getting rid of bites is also very complicated. Different products, organic or not, exist on the market, products to be sprayed or pheromone traps, for example, but the fight against the box borer requires often renewing the treatments, without it being always possible to be rid of critters.
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