I don't know which individual hens are laying in my flock, just that the flock is averaging five to seven eggs most days (only got two today, though -- at least I got both of them before they froze!). I know my six EE's aren't contributing anything, as all but one of them lays green eggs (one lays a pinkish egg), and I haven't gotten a single egg from any of them since October.
However, if you want to do some checking and try to figure out which hens are laying without sitting out there for hours on end or building trap nests (trap nests also require a great deal of time as you have to check frequently to release trapped hens), you can do the 'finger' test -- holding the hen, see if you can fit three fingers between her pelvic bones just below the vent. If you can only fit two fingers, she's not laying. Three fingers doesn't mean she's laying every day, but at least it will give you some idea of who is paying for her feed and who isn't.
Kathleen