Hyalophora euryalus Eggs

We have received ceanothus silkmoth (Hyalophora euryalus) eggs of northern California origin.

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Ah yes, Hyalophora euryalus - the pride of the Pacific coast when it comes to Saturniidae. This large red moth is one of the largest in North America and a close relative to the better known eastern cecropia moth (H. cecropia). We've always wanted to rear and breed this species since we were little. Last summer we managed to get a handful of eggs to try, but since this species is a very disease prone and challenging species to rear, they all died off in the third or fourth instar. Several factors likely caused us to be unsuccessful, the main culprits probably being the lack of airflow due to indoor closed container rearing, and the overly high humidity which we discussed in this post.

Well, this year we have received another batch Hyalophora euryalus eggs and we have high hopes for our second rearing attempt for a number of reasons. First off, we will be rearing the larvae much earlier in the season than last year, about the same time that wild populations would be breeding around here. Thus, weather conditions couldn't be more favorable. Also, these euryalus originated from a local source not too far from our home, and thus they are well adapted to living in our exact climate and area. These two factors alone should hopefully boost our chances at least a bit for this tricky species.

We have also learned from our mistakes in the past, which should definitely help us out this year. Although outdoor sleeve rearing would be ideal, we do not have any hosts on our property so we will probably be forced to rear indoors again this year unless we get a potted host. But, this time we will make sure to give them some good ventilation in their containers by giving this screen lids and possibly putting them by a window. We'll also make sure to keep the humidity down but make sure the food stays fresh. This should minimize the risk of disease. Finally, we might experiment with new hosts this year that the larvae may do better on. Last year we just used the standard ceanothus (Ceanothus) which is extremely common here in California, and is a common wild host for the moth. However, the cuttings wilt quite quickly and the leaves usually get covered in mildew or are in poor quality as the season drags on. Thus, we might try willow (Salix) this year which is also common around here, but unlike ceanothus, will store well when placed in water and always has very vigorous, high quality foliage all season. We might also consider Prunus as it is a good host in general for Hyalophora, but it doesn't seem to be as commonly used by euryalus in the wild as other hosts. If we could find some around here, we could also consider madrone (Arbutus) or manzanita (Arctostaphylos), but we probably won't be able to. 

Anyway, here are the eggs below. They are quite large and oval like other Attacini eggs. The ground color is a tannish off-white mottled messily in brown, probably both as a pattern of the shell and from the adhesive secreted by the moth. Interestingly, they don't look quite the same as the ones from last year, which had a darker ground color, were a more purplish shade of brown, and had less messy, crisper mottling. It is likely due to the differences in the strains' geographical origins. 

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Authors
Alan Liang

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