While walking through an alder thicket on the Paradise Meadow Trail at Lassen Volcanic National Park (California), I noticed a caterpillar gorging itself on alder leaves. I took a couple photographs hoping to identify the caterpillar. Not being an entomologist I usually have little luck with such puzzles, but this time I met with success – I believe.
The gray dagger moth caterpillar is green with a brown dorsal patch which is wider on T1 and A1 through A8 segments. The outside edge of the patch is countershaded with yellow. The head is brown. The body is naked except for a few single, short hairs.
This caterpillar feeds on alders, apples, birch, elms and poplars in the summer. The caterpillar will pupate over the winter, usually against the bark of a tree.
The gray dagger moth (Acronicta grisea) is found in moist forests in Southern Canada and the Northern United States from the Atlantic to the Pacific. A medium-sized moth, its forewings are dark grey with black basal (area of the wing nearest the thorax) and margin dashes. The hindwings are white.
I am not including a picture of this nocturnal moth because I do not have one. My “rule” for this blog is that all photographs must be my own. I will need to get out at night and search for a gray dagger moth.