Moth traps use a light source to attract flying moths which are caught in the main body of the trap. They can then be identified and counted before being safely released.
Popular moth trap designs include the Robinson trap which is very efficient at catching and retaining specimens throughout the night. The Skinner trap is popular as it can be collapsed down for transport or storage. Heath traps tend to be smaller and more portable and have a vertical vane and bulb system which direct moths down into the trap.
Our own NHBS Moth Trap has been designed to be lightweight and portable and has been tested and approved by Butterfly Conservation. 10% of all profits from the sale of this trap are donated to Butterfly Conservation to help them continue their fantastic work.
For a more detailed introduction, take a look at the Guide to Moth Traps on the NHBS blog.