There are several small butterflies that resemble the Mission Blue and are occasionally found in the same areas. These are the Acmon Blue, Silvery Blue, Eastern Tailed Blue, and the Echo Blue. In flight, a Green Hairstreak may also resemble the Mission Blue. Major ways to differentiate them are as follows: the Acmon Blue has orange tags at the base of its wings; the Silvery Blue has only one row of distinct black spots on the underside of its wings; the Eastern-Tailed Blue has two small tails at the base of its wings; the Echo Blue has an entirely more faded appearance with less distinct margins and spots. Check the photos!
The Pardalis Blue is a close relative of the Mission Blue, it is another subspecies of the Icaricia icarioides group. Up in Oakwood Valley, or down by Crystal Springs, the two subspecies overlap in range. It differs from the Mission Blue in subtle ways – the females with entirely brown upper wings; males with thicker black margins on the upper wings.