It's called a Senlgrove Board, named after L.E. Snelgrove. Covered extensively in the archives, which can be searched at: http://listserv.albany.edu:8080/cgi-bin/wa?S1=bee-l Hits on Snelgrove are numerous (over 50). Particularly recommended are: http://listserv.albany.edu:8080/cgi-bin/wa?A2=ind9708D&L=bee-l&P=R1900 with a follow up a year later: http://listserv.albany.edu:8080/cgi-bin/wa?A2=ind9812D&L=bee-l&P=R703 I am currently experimenting combining Snelgrove swarm control with Killion methods for comb honey production. So far (about 3 days into the experiments) I'm happy with how things seem to be going, but it's definitely too soon to tell. Aaron Morris - thinking archives, search 'em early, search 'em often!