There is a way to hide the subdirectories from a directory of your choice on your Webserver.
Open the httpd.conf File, search for "<Directory>" and put the following lines inside after the last Directory entry:
<Directory /this/is/the/directory/ >
Options -Indexes
</Directory>
"/this/is/the/directory/" is the path to the document folder of which you want to disable the directory listing. The subdirectories will be touched too.
If the directory entry for this folder already exists (example the root folder), then just add the Option "-Indexes".
Note that this is a local path on your server machine.