You can't stop them downloading any of your images, but you can stop them from hotlinking (if you have full access to your webserver - simple apache rules).
For those interested, this is possible (explicitly banned Adobe WebCapture as well):
SetEnvIfNoCase Referer "^http://your_website" local_ref=1
SetEnvIfNoCase Referer "^http://another_site_linkable" local_ref=1
SetEnvIfNoCase Referer "^$" local_ref=1
SetEnvIfNoCase User-Agent WebCapture leecher
Allow from env=local_ref
deny from env=leecher
Originally posted by RuthBaby
u canx jus kill them...
right away.. im free now.. shall go in start my flamming skillz