Lingering Backend Processes

If a postgres connection dies without implicitly disconnecting from the
database, it seems that the backend processes hangs around
indefinitely. Does anyone know of a way to get around this??

I'm using Postgres 7.0.2 and ApacheDBI to connected. If I start the
web server with 10 servers, there is immediately 10 postgres processes.
If I HUP the web server, there become 20 postgres processes. If I stop
and then start the web server, the number of postgres processes will
remain the same.

Can anyone tell me if I'm doing something incorrectly, or if there is
another way to periodically kill of these processes? I've noticed that
even killing the postmaster processes will no kill of the backend
processes.

Thanks.

Arthur