It buzzes and hums, but that’s not always a nice side effect of summer temperatures: insects can be annoying and bite badly. There aren’t always effective countermeasures – sometimes there are.
repellent against mosquitoes
“Mosquitoes are farm animals, ask the frogs,” said the children’s book author Manfred Hinrich. But on mild summer evenings, the little animals can cloud the anticipation of the warm season. Not only that the itchy bites are annoying. Mosquitoes can sometimes be carriers of dangerous pathogens – also in Germany. “In the last few years or decades, we have had no more transmissions of dangerous pathogens by mosquitoes,” explains Helge Kampen, head of the laboratory for medical entomology at the Friedrich Löffler Institute.
Since 2018, only the West Nile virus has been circulating in Germany – a pathogen transmitted by mosquitoes, which in most cases causes a harmless infection, as Kampen explains. However, climate change could increase the risk. “Global warming means that mosquitoes develop faster and there are more generations per year. Blood digestion is accelerated – so the females lay eggs faster and more often, and the population density increases over the course of the year,” says Kampen. In addition, with rising temperatures, mosquitoes are also active earlier and longer in the year, making it possible for some new species to settle in Germany, such as the Asian tiger mosquito.
So how do you keep mosquitoes at bay? “Mosquitoes are attracted to different substances depending on their life stage,” explains biologist and drug researcher Andreas Rose from Biogents. Basically, these are substances such as carbon dioxide or skin scents such as lactic acid. When they want to lay their eggs, they are attracted to water. So-called repellents work quite well against mosquitoes. According to Rose, an effective repellent is diethyltoluamide – DEET for short. This is found in numerous mosquito sprays for the body. However, there are also special protective clothing whose fibers have been treated with effective insecticides, such as pyrethroids, according to Rose.
DEET products on ticks
Ticks are also particularly active in the warm season. They too can be carriers of pathogens that are potentially dangerous for humans – including Lyme disease. According to a study by the Robert Koch Institute (RKI), a Borrelia infection is detected in up to 5.6 percent of those affected in Germany after a tick bite. The pathogen occurs nationwide and can affect the nervous system, the joints and the heart, among other things. Contrary to what many assume, ticks do not jump on people or fall from trees. The little bloodsuckers sit almost exclusively in the grass, at least in this country. If a creature walks by, they feel this and board their host by stretching out their legs, as biologist Andreas Rose explains. The little creatures then migrate up the body via their legs and look for a particularly soft and protected spot where they then bite into the surface of the skin.
Products with DEET are not only effective against mosquitoes, but also against ticks. According to Rose, if you want to be on the safe side, you should not only treat the skin, but also the fabric of the clothing with appropriate preparations. Caution should be exercised when using DEET products on young children. In the meantime, however, substances have also been developed that are better tolerated by the skin and can also be used in children, such as IR3535 or Picaridin. There are also plenty of nature-based remedies on the market, but most of them are not very effective, such as essential oils. “Of all the substances found in nature, there’s really only one that works really well,” says Rose. PND originally comes from the leaves of the lemon eucalyptus tree and is also an effective remedy against ticks.
Avoid bees and wasps
If you want to end the evening with a barbecue on the terrace in summer or enjoy your afternoon coffee with a piece of sugary cake, you will inevitably be attracted: bees and wasps are always uninvited guests at the table in summer and sometimes solve severe problems, not only for people with allergies reactions off. The insects are particularly attracted to fermented drinks such as beer or desserts such as fruit, juice or jam, as biologist Volker Mauss from the Center for Wasp Science explains. He therefore recommends covering food and drink outdoors at all times.
But how can you protect yourself from bites? As banal as it sounds – it is best not to stay in places where there are bees and wasps. “When a bee or wasp stings, it’s actually always an accident,” emphasizes Volker Mauss. “That means the animals don’t come flying to actively sting you, but do so in a situation in which they feel attacked or are being constricted.” According to Mauss, effective repellents are hardly known to date. There is some research on tar bath oils that may be effective. “But that’s actually not something that you can recommend in a meaningful way.”
How many animals you have to reckon with depends on several factors. “There are good and bad wasp years. Most of the time, these alternate fairly closely,” explains Mauss. If you have a very bad year, then what follows is a very good year from the wasps’ point of view with a lot of animals. According to Mauss, more dangerous species are not to be expected in the course of climate change, but the hot and humid weather is making the animals more aggressive – and there could be more such warm days in the future. “In such weather, the bees and wasps show a clearer defensive behavior with a lower trigger threshold.” Nevertheless, the animals should by no means be killed, emphasizes Corinna Hölzel from the Bund für Umwelt und Naturschutz Deutschland (BUND). “Insects are the foundation of our ecosystem, they are food for birds, bats and fish and many insects pollinate our food crop.”