When do you tag Monarchs? As the length of daylight shortens in mid August and September, monarchs in northern latitudes, i.e. near the Canadian border, begin to migrate. Monarchs farther south will begin their journey a few weeks later.
BBEMA begins tagging Monarchs on Aug 18th – with a concentrated effort to have all tagged butterflies released by September 20th – a good rule of thumb: when the wild asters, especially goldenrod are in bloom, the monarchs are migrating.
How do the tags work – Each tagged butterfly must have a tag code (three letters and three numbers) for this system to work. To insure that they do, we create a series of tag numbers using numbers and the alphabet. Each year receives its own unique series. The tags are printed on waterproof ink on polypropylene sheets that have special 3M ¨ adhesive on the back and are organized in groups of 25 consecutive numbers.
The Tag – Monarch Watch tags are about ¼ inch round, made of weather proofed paper with a strong adhesive and weigh only two percent of the monarch’s weight. Each has a code number and Monarch Watch address printed on them.
Tagging Method – the tag is placed over the large, mitten shaped cell (discal cell) on the underside of the hindwing of the monarch.