Glover’s Silkmoth lays eggs on side of building

Subject: Moth Beauty in Northern AZ w/possible endangered eggs
Location: Flagstaff, AZ
April 8, 2016 12:21 pm
I found this gorgeous moth outside my work building this morning, April 8th, in Flagstaff, Arizona (7000 ft. in a ponderosa pine forest). Unfortunately, I didn’t get a look at the top side of her wings, but was entranced by the eyes and camouflage of the displayed side. Many coworkers reported walking right past her. I believe she’s female due to the string of eggs(?) next to her. My best (extremely novice) guess is that she’s a variety of hawk moth, but I would love a proper identification.
Also, I’m worried about the eggs. I imagine they are typically attached to tree trunks. With the nearest tree about 50 feet away, do you think they’ll find food? Is there anything I can do to help them?
Thank you!
Signature: Moth Lover

Glover's Silkmoth
Glover’s Silkmoth

Dear Moth Lover,
This is NOT a Hawkmoth.  Rather, it is a Giant Silkmoth, more specifically, a Glover’s Silkmoth
, Hyalophora columbia gloveri, the western subspecies of the Columbia Silkmoth.  According to BugGuide, the habitat is “Usually Alpine and Riparian (scattered in and among adjacent suitable habitats incl. foothills of the western prairies)” and the larval food plants include “Several Trees and Shrubs in the Rosaceae esp.. Prunus spp., Willows, and Larch … additional hosts are numerous incl. many other woody plants larvae may eat leaves of alder, birch, Antelope Bitterbrush (Purshia tridentata), buckbrush (Ceanothus spp.), buffaloberry, cherry, rose, Russian Olive (Eleagnus angustifolius), willow.”  It is difficult to speculate on the survival rate for the eggs laid on your brick building.  The first meal for the newly hatched caterpillars include feeding off the egg shell.  The young caterpillars then disperse and they may be lucky enough to find a host plant.  A mated female is heavy with eggs, and she may just be unloading some cargo before flying off the search for an appropriate tree or shrub.  If she is not mated, she will still be quite heavy with eggs, and she may be lightening her load pursuant to flying off the next night.  At any rate, we recommend letting nature take its course unless you can reach the eggs, in which case you can try to transfer the freshly hatched caterpillars to an appropriate food plant.

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