Numerous, unknown sawfly larvae are skeletonizing planted Smooth Alder (Alnus serrulata) within a Howard County seep. Their patterns appear to somewhat resemble the Dusky Birch Sawfly, but less bold and with a red/orange head instead of black. I would to know what species these sawfly are and whether they are native to Maryland. Photos were taken ~3:00pm on 7/28/21; measurement not included but larvae appeared to be ~0.5 inch in length.