htpd going wild

[n dhert]

FreeBSD 8.2-RELEASE, all sucerity patches applied, all ports updated to the
latest version (every week)

In the last 6 months I have experienced 3 or 4 times the httpd deamon
(apache-2 latest version) going 'wild',
that is: an ever increasing number of httpd processes is being launched.
In a top (shows default the 18 most consuming processes), after a short
time all the 18 top processes are httpd
It shows a load of 30, 40, and ever increasing

interactive response, loggin-in, etc... gets very slow...
I can only try to do
# apachectl stop
(which takes long to type, and get processed also :-( )

I already installed the FreeBSD port  mod_limitipconn
and specify in my Virtual hosts:
<VirtualHost *:80>
    Servername  mysubdom.subdom.topdom
    DocumentRoot "my__document__root"
    <IfModule mod_limitipconn.c>
    <Location />
       MaxConnPerIP 3
    # exempting images from the connection limit is often a good
    # idea if your web page has lots of inline images, since these
    # pages often generate a flurry of concurrent image requests
    NoIPLimit image/*
    </Location>
    </IfModule>
</VirtualHost>

But seems no help ...
I can't figure out what can be the cause...
My apache is the latest for FreeSBD, I don't think it's a bug in Apache,
Is it some external websurfer/crawler that causes this huge load ??
I looked in the log files but can't find a 'smoking gun'
Any one ideas how to find the cause and how to deal with it ??