Help!!!

I need help with a new house guest I have. I was on the loo this morning when I notice a sizable beetle crawling up the door, after finishing my erm business. I saw it was a ladybug, HUGE for a lady bug, so I put it on the window sill, made it some sugar water as thought It might need a boost, it drank/ate some of that.

Came home at lunch still there, so made a sort of house for it from some green stuff that I got in a small glenfidick tin, put some more sugar water down and thought it owould be on its way.

Now home again and its still there, what do I do? Keep it warm, cold? What do they eat apart from aphids (they dont sell aphids in waitrose)... Please help me as I dont know what to do with him/her...anyone know how to sex ladybirds?

I await your answers..