Is it possible creating capped collections automatically at the first
insertion?

I receive some "packets" from a client. This data contains a name as
the first field. I don't know all these names "a priori", but I'd like
storing those data in capped collection (size is known). As far as I
know, if I db.insert("name") I'll create a no-capped collection... can
I change such behaviour? I'd like to avoid checks for existing tables
before storing (I can receive thousand of packets with the same name
and this check is unreasonable...).