I know the problem Rosella cos of Sasa and I have to thro a very elaberate performance to trap her. I also have arrangement with the vet to ring when I have caught her.
First is to know where she is and have a carefully prepared plan.
She was safely on her sofa in the study...............she is not using it any more!..............then was to start shutting all doors so only place she could run to was into hall and I blocked off the stairs. Once she was in hall shut study door and I ahve a big cage with the whole of one end that opens.
Next was to corner her with the cage, one end covered and other end open and theory was she would run into it.......sigh.
She didnt and it took nearly an hour of trying to get her to go in, I tried pushing gentley, stroking............cant touch her but she was so terified she was frozen and when she realized she was trapped she was crying pityfully and it was breaking my heart................and eventually she ran in but it was so hard. She is also very heavy and I cant attempt to pick her up over the cage and know from last year she is very very strong and quick, I stand no chance holding her.
I think its so hard when they are so scared and Kocka was too but she was smaller and lighter and I wasnt ill then but she used to hide from me and a couple of times I could not find her in the house at all although I knew she was there cos the cat flap had been shut and thats how she knew of course!
I wish you luck with Billy and hope you can catch him without too much stress for both of you