cocoons

I have been rearing North American Saturniidae for many years. Here on PEI in eastern Canada, where all Saturniidae species are single brooded, except for Dryocampa rubicunda which sometimes tries a second brood, I over winter my breeding stock in sandwich sized plastic storage tubs. I use Gladware here, which is similar to Tupperware. I put the cocoons in the tubs (lids on tight, no air holes) in October and set them in one of the crispers in my refrigerator and leave them there until I see the first cabbage white butterfly in the spring, usually around Mothers' Day. Then I begin taking cocoons out of the cold storage containers, usually two or three one day, none the next, and then two or three on the third day, none the next and so on until I have taken all out of cold storage before the end of May. I then have regular eclosions starting in early June and lasting into late June and early July, in sync with the flights of local populations.
I do not put any moisture in with cocoons. Almost every year I have close to 100% eclosions, and generally have good success getting pairings with wild males. If I want to pop a few early, I put them in a spare bedroom with an
electric space heater and crank up the heat to about 85 F. It works for me and I do not mist them. If I am storing naked pupae (rubicunda, virginiensis, or local Sphingidae or butterflies),
I put a paper towel in bottm of same type storage tub, moisten it with literally no more than two drips of water and let the naked pupae rest on top of the paper towel, lid on tight, again stored in crisper part of refrigerator, where a normal person would keep lettuce, cabbage, and other leafy vegetables from wilting.
If you want to lightly mist the cocoons once when you put them in the containers, that likely would not hurt, but it might encourage some mold on the outside of the cocoons.

Bill Oehlke

If your rearing cage gets some shade, as the cocoons in the wild would, then the moths should emerge in sync with some of the wild flight.
If your cage, however, gets full sun most of the time, due to its location, or acts like some kind of a heat trap, then your moths may emerge ahead of the local flight.
In the wild, cocoons that are in relative close proximity (within a couple of miles of each other) will experience different amounts of sunlight and warmth in the spring. Some will be under fallen leaves or even snow, some will not; some will be on the south side of a tree in a relatively clear area; some will be on the north side of a tree deeper in the woods, etc., etc. Hence your wild cocoons will emerge on different dates, despite their proximity because of the amount of warmth they experience. I suspect that cocoons in a cage such as you have described will yield moths within a very short time span from the first emergence of a moth of one species to the last emergence of a moth of the same species.
The fridge crisper technique works for me, and allows for setting out mating cages over a much more extended flight season. It also gives me a good idea as to the duration of the wild flight.
Our spring weather here fluctuates greatly and we tend to get much rain. I can have females emerge in a warm period and then see the temperature drop considerably for the next several days or we can have periods of very heavy rains for several nights in a row. It is therefore very useful for me to have females out a various times, still in sync with the natural flight.
Bill Oehlke

It is always interesting to read rearing accounts from others. I am surprised (not disputing your account, just surprised by it) that you get pupation over several weeks from eggs deposited on same date. Here my larvae from eggs from the same female on the same date usually spin up within just a few days of each other, but I am rearing them in very large sleeves so they are essentially experiencing the same conditions. I would imagine, however, that just as pupal development depends upon warmth and sunlight, larval development would depend on same items, so in wild, or under different rearing conditions, eggs from same female, deposited on same date, would develop at different rates due to warmth (sun or shade), and possibly based on foodplant, or maybe just a gene pool that supports varied development.
In New Jersey, where I grew up as a boy, if there was a long cool spring, followed by a cool summer, sometimes we would only see a single brood of lunas that year. Usually there were two broods each year.
If we had an early warm spring, and a warm summer, sometimes there would be a partial third brood of lunas, whereby some larvae which spun up on same date under same conditions would continue development in pupal stage and emerge within two to three weeks, sometimes when it was obvious that there was no time for offspring to mature before onset of cold weather, while other pupae would overwinter.
During each of the last two summers here on PEI I have reared 500-600 polyphemus to cocoon stage. Each fall about two or three moths emerge in September early October (not possible here for their offspring to mature), but the others
overwinter. So far, lunas reared here under same conditions and in same time frame as the polyphemus have not produced any adults in the fall. When I harvest the cocoons (usually mid August early September), I bring them indoors where average temp stays around 65-70. I don't put them in cold storage until near end of October.
I don't have much experience with offspring from sibling pairings as it is relatively easy for me to get pairings with wild males.
I do get many reports and digital images from people who have found a polyphemus or luna caterpillar or cocoon at a time and in a state or province where the pupae of those species would normally overwinter. The people have looked at the cocoon and then put it in a box or jar on the shelf in the warmth of the house. I usually get the email from them when they discover the moth flying around in the house in late January early February when it is cold outside with no foliage on the trees, and there is snow on the ground. My interpretation has been that the increasing photo period starting December 21-22??, coupled with the warmth causes the pupae to break diapause and begin to develop.
In another forum on Clark's site there is report of wild euryalus turnig up at a light in Santa Cruz County, California, just the other day. Poster said it has been warm there this spring. Usually the reports for central California euryalus flights start to arrive mid March into April, and from northen California they begin to fly in May-June.
There is still much to learn about these insects.
Bill Oehlke

Bill,

While I have no doubt that heat and sunlight may play a roll in the eclosion time of the moths, I think that individual characteristic between each moth probably has the biggest impact.

A few years ago I rasied a group of imperial moths from egg to adulthood. The eggs all hatced the same day. The larva all grew up in the same rearing cage inside my house, and pupated within a few days of each other. I put them all in the fridge on the same day in the fall, and removed them all on the same day in the spring. They were all transfered to the same container i had for eclosion but hatched very differently. Even though they had all pupated within a few days of eachother and were exposed to basically the exact same conditions since that time, there was about a 3 week span of eclosions.

The same thing happened with a group of Lunas I raised too except there was no refridgeration. They all spun up and pupated within a couple of days of eachother, but their eclosion times were spread out over more than a week, even when the rest of the conditions remained the same for them.