H. euryalus Eggs Hatch

Our Ceanothus Silkmoth (Hyalophora euryalus) eggs have finally hatched today.

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This morning when we checked on our Ceanothus Silkmoth eggs at 11:00 AM, we were delighted to find that 18 newborn Ceanothus caterpillars were wandering around inside. We were not sure when they hatched exactly since we weren't watching them the whole time, but it was probably within the past hour based on the fact that many had literally just walked out their shells and had soft, untanned cuticles. Some of these untanned individuals can be seen in the upper and bottom left-most photos and the two bottom right photos; their tubercles have a brownish pink hue. Later in the afternoon, three more hatched making 21 newborns in total for today.

Saturniidae caterpillars usually don't begin feeding until dusk of the day they hatch, so we had some time to figure out what containers to put them in and what host plants to use. We separated the 21 caterpillars into four groups of four and one group of five and place them in the same type of air-type plastic containers we used for the Cecropias. We then went our searching for different host plants, namely ceanothus (Ceanothus) and willow (Salix) to see which they would prefer. Willow was easy to obtain because there are a few very nice trees right across our house, and is very abundant in general in our area. We would like the caterpillars to settle on willow because of this, but unfortunately it is probably not an especially good host choice for them. After, picking a few willow leaves, we found three varieties of Ceanothus: a decently sized and good condition Ceanothus thyrsiflorus bush at Memory Park, three very good condition Ceanothus griseus horizontalis plants at a residential home a block away from our house, and a ton of huge but poor condition Ceanothus griseus at Albany Middle school and along Cerrito Creek. There were also a ton of different Ceanothus varieties at a residential house a few blocks away but there was only one bush of each and most of the varieties had tiny, prickly leaves so we did not consider those. The thyrsiflorus leaves are bigger and softer looking and is probably the better host, but there is only one bush. On the other hand, the griseus and griseus hor. have small, tougher looking leaves but they are much more abundant. So, we have sort of a tough decision here because the best looking host choice is the rarest and the worst looking one is the most abundant! In the end, we picked some thyrsiflorus and griseus horizontalis leaves and put them in the containers along with the willow leaf to give them a choice between the three. After an hour or so after putting in the leaves, only two had settled down on the willow and made a few nibbles, while almost all the rest seemed more interested in the Ceanothus, especially the thyrsiflorus. We will see tomorrow morning which hosts they truly settle on and hopefully it will be clear which one they prefer most. The caterpillar and egg count for today is: L1: 21; unhatched eggs: 5.

- Alan