FYI The new non-machinable stamp is called Colorado Hairstreak (purple butterfly). The yellow butterfly is the California Dogface.
On May 17, 2010, the USPS issued the first stamp in the Butterfly Series.
In late 2009, the USPS unveiled the first butterfly stamp for greeting card envelopes that required additional postage (an extra 20¢) than the standard one-ounce rate covered. This would apply to envelopes that couldn’t be sorted on the USPS’s automated equipment, otherwise known as “nonmachinable.”
Some of these nonmachinable envelopes include those that are oddly-shaped or vertical, lumpy, rigid, or with clasps, ribbons, or buttons on them. Even if an envelope weighed less than one ounce, but was unmachinable, it would need this stamp. However, letters that were simply heavy didn’t necessarily need it. The two-ounce rate at the time was 61¢, and this stamp was 64¢, so they would be overpaying by 3¢ if they used it.
The USPS worked closely with the greeting card industry on this new stamp. Prior to this issue, some greeting card envelopes would be imprinted with “extra postage required.” With the creation of this new stamp, the Greeting Card Association encouraged its members to print a butterfly silhouette on the envelopes of cards that would require this additional postage. Reflecting this close working relationship, the 64¢ monarch butterfly stamp was issued on May 17, 2010, at the National Stationery Show held at the Jacob Javits Center in New York.
https://www.mysticstamp.com/Products/United-States/5346/USA/
