Larsen traps work best with a "call bird" that is a magpie caught in another area. The local population will be incensed by this interloper and will try to get at it thereby being caught themselves. As yours have taken eggs one or two might fall for the trap, but you are unlikely to catch the whole tribe.
Go to your local game suppliers/merchants and ask around. The Larsen traps often do the round during the season, though I suspect you are a bit late at this time of year.
Try using pepper eggs (loads of white powdered pepper) and also fake rubber eggs. Or what about a spring trap on the pop-hole to the hen house. I take it the hens go out through a pop hole, and not through a open door, because if not then start by making a pop hole entrance, possibly with a little tunnel first.
All the best
Sue
Dark Brown Eggs