The caterpillar, which only lives around birches, is currently leaving the trees to pupate in the ground. It is during this period that it is dangerous for humans and animals. The larva carries a poison that is related to that found in fly agaric, and if ingested it can lead to death.
– It is most relevant for grazing animals, if you ingest enough poison you can die, says Martin Sjödahl who is a management strategist at the County Administrative Board in Kronoberg.
Clear signs on the trees
Martin Sjödahl calls for attention if there are birches in the area. The sign that the blue-black birch bark beetle is present in the trees is that entire branches are bare, while other parts of the tree are undamaged.
The larvae always leave the midrib on the leaves. When the nerve cord then withers, it takes on a reddish-brown color that is visible even from afar. Heavily infested birches become completely leafless in late summer.
Found at preschool
This year, among other things, the larva has been found at a preschool in Växjö, but there are no cases in Sweden where people have ingested the poison. Most vulnerable are ruminant grazing animals, where there are cases in Denmark where animals have died. In Sweden there is a case in Ystad where a puppy ate a caterpillar and died.
– If you have birch trees in your pastures, you should pay attention, and if you see signs, you should keep the animals somewhere else, says Martin Sjödahl