Unusual Pink Caterpillar is a Sawfly Larvae

Observation by Bernice Nicholi:

This was seen a few weeks ago, never seen something like this before.

Comments from LEO Editors:

In early July, Harvey Hoffman II posted an observation of an unusual green bug found near Aniak. We sent that photo, and the photo of this pink caterpillar, to Jozef Slowik who is an entomologist at the UAF Coorperative Extension. As it turns out, both the unusual green bug and the pink caterpillar are the same insect! Jozef 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.

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.