I was going off the top of my head, I stand corrected. The California Dogface Butterfly stamps have apparently been retired however they are forever stamps so they can still be used if you have them. The new non-machinable surcharge stamp is the Colorado Hairstreak Butterfly stamp which costs 88¢ as you stated. Cheers.

https://store.usps.com/store/product/buy-stamps/colorado-hairstreak-stamps-88-cents-S_121204