Technical Abstract: The syntypes of Siphonophora fragariae var. immaculata Riley were rediscovered in the Aphidoidea collection of the United States of America National Museum of Natural History. Previously, S. fragariae immaculata was largely lost and forgotten. Through examination of the specimens, we hereby establish it as the senior synonym of Macrosiphum euphorbiae (Thomas). Reversal of precedence can be validated, however, and we establish S. fragariae immaculata as a nomen oblitum and M. euphorbiae a nomen protectum with respect to each other. In uncovering the original description of the Riley species, we also found a description of Aphis rapae var. laevigata Riley. We have not found this name anywhere else nor found any type specimens. Based on Riley’s succinct description and host plant identity, we consider it a nomen dubium synonym of Myzus persicae (Sulzer). Because the short articles publishing the two aphid names have been missing from taxonomists’ libraries, they are reprinted in their entirety.