The threatened species of the insect orders Heteroptera, Lepidoptera a
nd Coleoptera found in Ruissalo, an island with widest oak forests of
Finland, are listed. Of the 154 species of threatened Lepidoptera in F
inland 12% (19 species) and of the 332 species of threatened Coleopter
a 16% (53) are found in Ruissalo. A considerable part of the threatene
d species of both Lepidoptera and Coleoptera are dependent on oak. The
most important areas of the oak forests are already under protection
and the other parts of them belong to the national conservation progra
m of herb-grass forests. A forestry plan prepared by the City of Turku
considers the nature values of the island of Ruissalo.