The sun is shining and the temperature is rising. For us, so much the better, but for Germany’s forests, alarm bells are ringing. The bark beetle is waking up once again - and that spells disaster for the trees. 

Bark beetles kill trees by laying their eggs in the bark

With climate change bringing warmer weather, the bark beetle season in Germany is starting earlier each year. When the temperature rises above 16 degrees, millions of beetles come out of their hidey holes and tunnel into the bark of living trees.

Once embedded, the beetles begin to lay eggs - up to 30.000 of them each year - and the resulting larvae begin to feed on the inner layers of the bark, severely weakening the tree. Healthy trees are able to produce a sticky sap that protects them from bugs, but after two tough years of heat waves, droughts and storms, a concerning number of trees in Germany are too weak to fight back 

Another plague expected this year

In 2019, around 12 million cubic metres of forest in North Rhine-Westphalia alone were lost to bark beetles - and it is feared that this year will be just as bad. “The situation in the forest is very tense. We expect damage caused by bark beetle infestations to be at least as high as last year,” said Andreas Wiebe, head of the NRW State Office for Forest and Wood. 

The situation has been exacerbated by a very mild winter which barely damaged the larvae, pupae and eggs laid at the end of last year. “This spring, the number of bark beetles that have been hibernating alive under tree bark and on the forest floor is immense,” said Wiebe. “Our experts have found over a million beetles per hectare in some forests.” 200 bark beetles are enough to kill a drought-stricken spruce tree in as little as four weeks. 

Forest owners call for aid

The Association of German Forest Owners is therefore calling for the 800 million euros of aid promised by the federal and state governments last year, to reach forest owners as quickly as possible. The storms in February knocked down multiple trees, which need to be cleared before they become breeding grounds for more bark beetles. 

North Rhine-Westphalia has also this year begun using so-called Trinet traps in an attempt to drastically reduce bark beetle populations. The trap works by releasing a scent that is fatally attractive to male bark beetles. When they fly towards it, they hit a net that is coated with a fatal toxin. The traps have already been laid to catch the first swarm flight, and will remain in place until early June.