I've placed this as Eastern because it lacks the more extensive reddish wing veination seen in the California examples . Also, the distribution of the Box Elder in Utah suggests that the tree population around Salt Lake City was introduced by humans, seems reasonable that the bugs came along as well. It is possible that both species occur in my area. Side note- the insect only infests female (seed bearing) trees, plant only the male trees and no bugs. The tree, Acer negundo, has also become naturalized in the pacific northwest, no doubt one of the Boisea species will be found associated.

the photos we have from Oregon and California both seem to have more prominent red veins in the wings. Strangely none of the written sources I've seen have mentioned this, but of course the name "rubrolineatus" suggests this distinction! I think perhaps the other specimen we have from Utah belongs under this species, too. I will update the guide accordingly - thanks!