The first week of December 2005, I saw that World Wide Butterflies was offering eggs of Actias maenas. I bought thirty eggs. I’ve never reared butterflies or silkmoths before, and I know it's not a species recommended for beginners, but I decided to give it a shot.

The recommended foodplant is Eucalyptus gunnii, which nobody sells in Norway. I managed to import three small potted plants from Denmark. I also contacted a plant nursery in England, which kindly agreed to send me ˝ kilo of frozen Eucalyptus gunnii leaves.

The eggs arrived 12/21/05. The first egg hatched the next day. After a week, a total of 10 eggs had hatched. The rest did not hatch. I kept the larva cages in a spare bedroom, where I turned up the heating to 25 C with a humidifier going full blast. Six of the larva started munching away on the potted plants at once. Four of them would not eat and kept crawling off the plants. After five days, these were dead. The other six were doing fine, and were in the second instar now. At the end of the following week, they were all in the third instar and eating like crazy. The potted plants were now in a sorry state. Clearly there wasn’t enough foliage for all the larva, so I divided them into three groups:

Group A. Two of the larvae where kept on the potted plants. One of them died in the third instar. The other one died in the fourth instar. I noticed that both died when trying to shed their old skins. I don’t know why.

Group B. Two of the larvae were fed leaves coated with the artificial diet, suggested in the Silkmoth Rearer’s Handbook by Brian O. C. Gardiner. The larva ate the leaves without hesitation, but both died the next day after producing a wet sticky frass.

Group C. Success at last!!!!! The two last larvae were given a choice between “plain” thawed E. gunni leaves and thawed E. gunnii leaves pickled in my version of Smith’s elixir. The leaves were tied onto planting sticks. The larvae wouldn’t eat the “plain” leaves, but they loved the “pickled” leaves. Both larvae made it to the fifth instar and emerged as two large male moths.

Here’s the recipe:

200 grams of sugar
25 grams of potassium nitrate
Dissolve in one liter of boiling water

This mixture is poured boiling hot over 300 grams of E. gunnii leaves in a canning jar. When cooled to 60 C, I added four tablespoons of Biovite vitamin tonic (for humans) and allowed the mix to cool overnight.

I kept the jar with the leaves in the fridge, and took out only the amount to be eaten each day. In the third instar they ate about two leaves each per day. At the end of the 4th instar they ate three to four leaves each per day. At the end of the fifth instar they ate six leaves each per day.

None of the larvae spun cocoons. After they cleared their guts, they spent a day bunched up, with their heads tucked in and all true legs off the stick. The larvae spent the next three days crawling non-stop around the cage. At the end, I could see the larvae where changing shape and that all the segments with prolegs were growing stiffer and losing mobilitiy. On the fourth day, the larvae were both laying on their sides at the bottom of the cage. After two more days they were looking putrid and I thought they were dead. But when I prodded them, they wiggled. After three more days, they cast their old larval skins and survived as two healthy looking pupae. This happend during the night, so I didn’t get to see it. All this happend while they were still in the larva cage, which was a low clear plastic container (35cm x 15cm x 15cm).

I had built a large screen cage (100cm x 50cm x 50cm). I had planned to wait two weeks, to let the pupae harden, before moving them to this cage. The first male moth emerged after thirteen days, while I was at work. He was still in the larva cage and had batterd his wings to shreds. I moved the last pupa to the screen cage. After two more days, the last male moth emerged in A1 condition, wingspan 12.7 cm.

All in all, frozen leaves seem to be a simple and effective way to rear moths during the winter. I plan to freeze oak, willow and cherry leaves this spring, to try out next winter.

Best Regards

Rolf Tornoe
Norway

John Irion recently sent me this query re Rolf's article:

"Do you think in Rolf Tornoe’s article, he meant to pour the boiling mixture over the leaves. I tried making the mix and poured it over evergreen oak and viburnum leaves and each time it bleached the leaves and made them thin and tissue like. I’d really like to see if the technique can help me in winter. I wonder if the mix should cool first at least some???? Just wondering on your thoughts."

Rolf sent this clarification:

"In the book, they recommend soaking leaves in the cooled mixture over night. But, like you said, E. gunnii leaves are very thick and tough.

I tried first soaking the leaves in the cooled solution, and it did not seem to penetrate the leaves. Also the leaves soaked in the cooled mixture mildewed after two nights. I therefore poured the mixture, boiling hot, over the leaves. This turned the leaves a greyish green color and they seemed a bit softer. But they were still thick and tough.

Out of curiosity, I've also tried boiling gunni leaves in a sugar solution for 1 hour. This had very little effect on the leaves thickness and consistency.

I have so far only tried this on E. gunnii leaves."

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