Losing Unicod chars

[Chip]

I was under the impression that all the string and file handling methods in
vb.net defaulted to UTF-8. I am losing chars and I don't know why.

Dim fs As New FileStream(MyFilename, FileMode.Open, FileAccess.Read,
FileShare.None)
Dim Reader As New StreamReader(fs)
Dim StrList As String

If FileExists(MyFilename) Then
StrList = Reader.ReadToEnd
Reader.Close()
fs.Close()

File being read in: "Las telarañas de Carlota"
After read, StrList = "Las telaraas de Carlota" (note missing "ñ")

Can anybody help?