If unopened, the glue boards for the Catchmaster Ovi - Catch AGO Mosquito Trap will last indefinitely as long as they are stored in a cool, dry place. Once in use, they should be replaced every 30 days, or sooner if they become full.
Yes, the Catchmaster Ovi - Catch AGO Mosquito Trap Replacement Glue Boards for the Catchmaster Ovi - Catch AGO Mosquito Trap can be purchased separately
According to a rep with the manufacturer, they typically suggest 4-8 Catchmaster Ovi Catch Mosquito Traps per acre depending on the habitat on the property. So 3-4 for a half acre should do great. Be sure to follow all the instructions with the traps to achieve the best results.