This odd, bright green, bug is a species of sawfly belonging to the family Tenthredinidae.
Observation by Harvey Hoffman II:
The observer thought it was a mosquito, and she saved it because it was so odd. The bug is green and has long antennas. First time finding one just like it. She was kind enough to let me take a photograph and post to LEO on her behalf.
Jozef Slowik, entomologist with the UAF Cooperative Extension writes:
This green bug, as well as the pink caterpillar described in the recent observation from Grayling, are the the same bug, a sawfly in the family Tenthredinidae. There are a number of species in the family in Alaska. Some can be quite destructive to alder and willows. Most are just present in the environment are rarely noticed.
Comments from LEO Editors:
There are three species of alder-feeding sawflies in Alaska: the alder woolly sawfly (Eriocampa ovata), the striped
alder sawfly (Hemichroa crocea), and the European green alder sawfly (Monsoma pulveratum). The striped alder sawfly is native to Alaska, while the green alder and alder woolly sawflies are considered non-native or invasive. These three sawfly species emerge between mid May and mid June, and can cause extensive damage to alder leaves. More information on sawfly species of Alaska can be found here.
As Jozef mentioned, sawflies can cause extensive, visible damage to vegetation. In late June, Michael Opheim submitted an observation of mysterious holes in alder and willow leaves. Jessie Moan commented that a likely culprit may be a species of sawfly.