I'm in the middle of building an LED driven moth trap. It uses a number of different frequency LEDs to generate the best light temperatures to attract months (apparently); I'll let you all know how well it works when I get it finished
I remember talking to a Moth expert once on a camping trip.
He was always going out with his moth trap to catalogue what he found.
He explained how some moths can be very territorial and incredibly isolated as they may not venture very far from a single bush.
This meant what he found in one small hedge row could have no bearing on the moths in a hedge a few metres away.
He said this makes it very difficult to estimate general moth numbers across the country as unless you surveyed every bush etc in a specific area a random sample was no real indication of numbers or species.