Dieser Code geht in die andere Richtung, aber er behandelt die Frage "Wie finde ich ein USB-Laufwerk":
using System.IO;
// . . .
foreach (DriveInfo removableDrive in DriveInfo.GetDrives().Where(
d => d.DriveType == DriveType.Removable && d.IsReady))
{
DirectoryInfo rootDirectory = removableDrive.RootDirectory;
string monitoredDirectory = Path.Combine(rootDirectory.FullName, DIRECTORY_TO_MONITOR);
string localDestDirectory = Path.Combine(destDirectory, removableDrive.VolumeLabel);
if (!Directory.Exists(localDestDirectory))
Directory.CreateDirectory(localDestDirectory);
if (Directory.Exists(monitoredDirectory))
{
foreach (string file in Directory.GetFiles(monitoredDirectory))
{
File.Copy(file, Path.Combine(localDestDirectory, Path.GetFileName(file)), true);
}
}
}