On Alnö and in adjacent Söråker near Sundsvall are some of the places in the country where the mnemosyne butterfly still remains.
In early summer, it is possible to see the large white butterfly that has black spots on its wings and flies in a characteristic way.
But the species is highly endangered and on Alnö a project is now being carried out to give the mnemosyne butterfly greater opportunities to survive.
- Here we have removed a lot of spruces, says Annika Carlsson at the county administrative board in Västernorrland.
Picky caterpillars
The larvae of the mnemosyne butterfly only eat the plant small nun, a species that disappears when the spruce forest takes over the old pastures.
But the restoration of the butterfly's environments seems to be yielding results.
- There was a downward trend for quite some time on Alnö, but now this year more people have flown, says butterfly enthusiast Håkan Sundin.
"Very rare"
Annika Carlsson thinks it is important that the species is preserved.
- It is very rare and is found in three places in the country, Blekinge, Uppland and here in Västernorrland.
So we have a great responsibility to maintain these lands, she says.