Saturday, June 2, 2018

Ceanothus Silkmoth - Part 1

Hyalophora euryalus - hi-all-oh-for-ah yur-ee-ah-lus - the name rolls off my tongue like a little jingle and makes me happy at the thought of this burgundy and gray moth with long white fang-like crescents. My first introduction to this beauty was as a teenager at a summer camp when I found a freshly-emerged male on the screen door of the girls cabin one morning in the Methow Valley of Okanogan County. I was instantly smitten and have long wished to rear this species from egg to adult. I might have done it sooner if I was inclined to stay out at night at the right time of year and set out some black lights, but sleep and daytime butterflies were a stronger pull!

Ceanothus silkmoth (Hyalophora euryalus), May 7, from Vancouver, WA
On May 7, a friend in Vancouver, WA posted a picture of a giant moth outside her garage...not only was I excited to see that it was female, but I noticed what appeared to be two eggs stuck to the siding! A few messages back-and-forth later, my friend had the moth captured in a large container and I could barely concentrate on work the rest of the day before I drove the 45 minutes to her house. Sure enough, there were two eggs still stuck to the siding, so I gathered those too and returned home with my prize. Over the next few nights I gathered a total of 81 eggs before the moth expired.

Ceanothus silkmoth adults, like other giant silkmoths (Saturniidae), do not eat and only live about a week. You might think of the adults as the equivalent of flowers: visible and pretty and allow plants to reproduce, but don't last very long.

Hyalophora euryalus eggs
I gave half of the eggs to a colleague who studies Saturniids. He advised me to split the brood between Douglas Fir and Pacific Madrone because the larvae will look quite different in the final instar (a hostplant-induced morph). 39 of my 40 eggs hatched a week and a half later. Because the eggs were laid over several nights, the larvae hatched over three or four days; the first ones doubling in size by the time the last ones had finished hatching. This variation in hatch date and growth rates has resulted in larvae of many different sizes even though they are all from the same parent.

Eggs starting to hatch!
Butterfly and moth caterpillars hatch relatively quickly and with little warning (some eggs turn clear but these don't) so I've never had the opportunity to capture the moment when the caterpillar crawls out of the egg...until now! While watching the caterpillars that had already hatched, I noticed an egg moving and a caterpillar head breaking out of the end, so I grabbed my camera and quickly took several photos.

Hyalophora euryalus larva hatching

May 19-22

Hyalophora euryalus - newly-hatched 1st instar
Hyalophora euryalus - newly-hatched 1st instar
Hyalophora euryalus - newly-hatched 1st instar
Hyalophora euryalus - newly-hatched 1st instar
Hyalophora euryalus - newly-hatched 1st instar
Hyalophora euryalus - newly-hatched 1st instar (left) next to mid-1st instar (right), only three days apart!
Hyalophora euryalus - late 1st instar larvae
Hyalophora euryalus - late 1st instar larvae

May 25-29

Hyalophora euryalus - recently molted 2nd instar larva (left) and late 1st instar larvae (right)
Hyalophora euryalus - recently molted 2nd instar larva (left) and late 1st instar (right)
Hyalophora euryalus - recently molted 2nd instar larvae
Hyalophora euryalus - recently molted 2nd instar larva
Hyalophora euryalus - recently molted 2nd instar larva
Hyalophora euryalus - recently molted 2nd instar larva
Hyalophora euryalus - recently molted 2nd instar larva
Hyalophora euryalus - recently molted 2nd instar larvae

May 29

Hyalophora euryalus - late 2nd instar larvae
Hyalophora euryalus - late 2nd instar larva
Hyalophora euryalus - late 2nd instar larva
Hyalophora euryalus - late 2nd instar larvae
Hyalophora euryalus - late 2nd instar larva preparing to molt
Closeup of the previous picture: note the new set of spines growing sideways just under the now-transparent skin!

Hyalophora euryalus - late 2nd instar larva (left) and freshly-molted 3rd instar larva (right)
Hyalophora euryalus - 3rd instar larva (top) and late 2nd instar larva (bottom)
Hyalophora euryalus - freshly-molted 3rd instar larva with its shed skin (left)
Hyalophora euryalus - 3rd instar larva
Hyalophora euryalus - 3rd instar larva
Hyalophora euryalus - 3rd instar larva. Can you see the tiny eyes? Three are visible as shiny specks on the black patch near the lower right mandible. Many people mistake the large head capsule as two large eyes - it actually contains the muscles used to control its jaws. Caterpillars have very poor eyesight. 

June 2

Hyalophora euryalus - mid-3rd instar larva (I'm loving the colors!)
Hyalophora euryalus - mid-3rd instar larva
Hyalophora euryalus - mid-3rd instar larva
Hyalophora euryalus - mid-3rd instar larva
Hyalophora euryalus - mid-3rd instar larva (yes, they really are that blue on top!)
Hyalophora euryalus - mid-3rd instar larva
Hyalophora euryalus - mid-3rd instar larva with partially black scoli and feet
Hyalophora euryalus - mid-3rd instar larva  with partially black scoli and feet
That's all for now!
For more information about these moths and their range, see the PNW Moths page and the BAMONA page.

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