Identification, Images, & Information
For Insects, Spiders & Their Kin
For the United States & Canada
Photo#1301137
Caterpillar

Caterpillar
Monroe, Snohomish County, Washington, USA
October 1, 2016
Size: 2 inches
Several eating Alder leaves. A few had their bottom 1/3 of their bodies in the air while feeding (yellow end).

Moved
Moved from Common Sawflies.

Looks like this may be a willow leaf?
In any case, there are no known North American alder-feeding sawfly larvae that look like this (but there are certainly more remaining to be discovered).

Moved

Tenthredinidae
I don't think it could be anything else.

 
and possibly Nematinae

Moved

Moved
Moved from ID Request.

Looks rather to be
the larva of a sawfly