Connie, this is strange but I have noticed this also this season. I NEVER had any worms left in the bowl when they were eating in all these years, but this year I have noticed that they will leave a few, although they eventually will come & finish them off in an hour or so. My batch of worms were larger this season than usual but I compensated for this by giving a few less worms. But I NEVER had this happen in the past. Your 12 to 15 worms is really about the right amount for mama, papa & four babies, and really not any too much. Are the ones in the new newborns? If so, they are not fed worms for the first 2 or 3 days. I have noticed that if I wait too long in the morning they do not come immediately like they do about the first 1/2 to 1 hour after sunrise.