I too have one of those high freq thingies and it has seemed to help. I use to put some plants outside on cooler days when they wouldnt get scorched by the heat and then bring them back in, but they would come back in with friends from the outdoors and those friends would climb onto other plants inside..

I got one of those high pitch cherp thingies and quit putting plants outside and no more bugs at all. Infact there are less bugs in that room then there are in any other room in the house.. and no pesticide. It could all be my imagination but it seems to work.