British Insects: the Families of Lepidoptera
Intkey is easy to use, and has many features that will help you make accurate identifications, including:
If Intkey (dated 5 September 2000 or later) is already installed on your computer, you can start the key.
To install the latest version of Intkey, run http://delta-intkey.com/win32/intk32.exe. With a broadband connection, installation takes about 1 minute. The size of the download is about 2MB, and the size of the installed program is also about 2MB.
The complete package is available on DVD.