Subject: moth identification help
Location: Benicia, California
April 10, 2014 10:18 pm
My kids and I love bugs. We found an egg sac in our yard that we have not seen before. We have been keeping an eye on it for a about a month (although I don’t know for sure how long it had been there before we found it). It hatched this morning and we found a beautiful moth (which we also have not seen before). I’m hoping you can give us some more info about what kind of moth it is exactly. Thanks so much.
This is a beautiful moth. It is a Tiger Moth in the subfamily Arctiinae, and it looks like a member of the genus Grammia, however we are having difficulty finding a visual match on BugGuide because of the black base on the underwings and the intricate pattern on the forewings. We also find the cocoon to be unusual in that no caterpillar hairs have been incorporated in its construction. We have decided to contact our friend and Arctiid expert Julian Donahue for his opinion.
Hi again Christie,
We emailed Julian and then telephoned, but he is running errands. We now believe this is Grammia ornata, and you can see a selection of images on BugGuide including this image on BugGuide which shows the black base to the underwings. The species is found in California. We are awaiting confirmation from Julian. We could not locate an online image of the cocoon of Grammia ornata for comparison.
Julian Donahue Confirms Identification: Grammia ornata
You’re right on, Daniel. Grammia ornata is a western North America species, occuring from Ventura Co., California north through the Pacific Northwest to southern British Columbia, Canada, east to northern Utah, and western Wyoming and Montana. (South of Ventura Co., California, it is replaced by the similar G. hewletti, described from San Diego Co., California).
Attached is a copy of Chris Schmidt’s revision of Grammia, which has color plates illustrating all the species. Both species are illustrated on p. 578, figs. 36 & 37. Schmidt_2009_Grammia
Thank you so much for your reply. I was wondering about the cocoon/egg sac as well. It looked like thousands of tiny oval eggs inside a silk web, but in the shape of a caterpillar. This one was on our deck under a planter, but we found two more on the underside of leaves on a nearby plant with the web curling the leaf around it. We have not seen any actual caterpillars in the garden, so now I’m wondering the sac and the moth were coincidental occurrences?? I would love to know more about the cocoon/sac if possible.
In your original email, you implied that you were certain the moth emerged from the cocoon. Now you don’t seem certain. In our opinion, the moth and the cocoon are not related.
Julian Donahue confirms our suspicions about the “Cocoon”
The “cocoon” doesn’t look like anything I’ve ever seen; almost 100% positive it’s not arctiid in origin (sorta looks like a sawfly larva to me, but that’s a wild guess and I have nothing to back it up).