Moricsala Nature Reserve (Latvian: Moricsalas dabas rezervāts) is a nature reserve in western Latvia (Courland).

It is situated on two islands in Lake Usma and consists of boreal, mixed broad-leaf and oak old-growth forest as well as swamps.

[3][4][5] Founded in 1912, it is the oldest nature reserve in Latvia.

[6][7] The nature reserve serves as a habitat for several rare species of moss, lichen and insects; for example, 222 species of butterflies can be found here.

For some of these butterflies, the nature reserve is the only known habitat in the Baltic states.