You've got Saturniidae eggs and are wondering how to care for them. Not much care is required in the egg stage.

If you received the eggs from either my father or myself, the date of deposition is usually recorded on paper or plastic inside the shipping envelope. Record this date on a piece of masking tape and affix it to the top of the egg storage container which could be a tightly lidded (no air holes) glass jar, a plastic tub, etc. I usually use rectangular, clear ziploc plastic tubs. They (about quart or litre size) can be used year after year, are quite inexpensive, are easy to clean and afford great visibility.

Do not put any foliage in with the unhatched eggs.

The eggs you have received were probably all deposited on the same night within an hour or two of each other as we only ship fresh eggs and the moths have peak activity periods for ovipositing. Eggs are fertilized as they are deposited. Thus all the tiny caterpillars should emerge within an hour or two of each other.

The little caterpillars literally eat their way out of their eggshells, and this first meal will sustain them for up to twelve hours, possibly longer. Some species like Automeris io will completely devour the egg shells and may not eat foliage for two or three days. My experience is that the larvae of most species usually emerge in the morning, often before I leave for work. If I have time, I usually place two or three host plant leaves in with the tiny larvae, not with the unhatched eggs. If I'm in a rush, I know the tiny larvae can wait for leaves until I return home from work.

The eggs in the above image are on foliage under outdoor conditions. If it appears that many of the eggs still have not hatched when I am prepared to offer leaves, I gently pour the unhatched eggs into a new container without foliage and just offer the foliage to the emerged larvae.

Putting foliage in with unhatched eggs can be disastrous for several reasons:

1) the leaves give off carbon dioxide which can literally suffocate the tiny larvae inside the unhatched eggs in the closed container,
2) the leaves also give off moisture which can condense on the floor of the container and "drown" the eggs, or
3) moisture can condense on the egg shell and cover the micropyle also suffocating the larvae.

Here on Prince Edward Island I have observed the following incubation times for eggs stored at a fairly constant 70 F:

Actias luna: ten to twelve days; as few as eight days with mid-summer heat (80+)
Antheraea polyphemus: fairly consistent at eleven to twelve days
Hyalophora cecropia: twelve to fourteen days
Hyalophora columbia: fourteen to nineteen days

Warmth generally hastens development and cooler temperatures delay development. Having the date(s) on tape on the tub(s) provides a guide as to when to expect emergence, but development times will vary with temperature so it is a good idea to use a clear tub for easy visibility. Eggs will also hatch in opaque containers like rinsed out ice cream tubs.

Yes, you can delay egg development by forced chilling (not freezing) in a refrigerator crisper, but cold storage beyond a week usually results in eggs that won't hatch or larvae that die in the early instars, probably because they assimilated some of their own non-excess body tissues during storage. If you are going to try a delay, better to do it just after depostion or receipt of eggs; best not to try.

Perhaps you wish to obtain eggs from your own mated females. If so, the females will readily oviposit in brown paper lunch bags or grocery bags. Inflate the bag, place the female inside after she has separated from the male and then fold down the top once or twice.

I move the females to new bags each day to keep egg batches separate so as to have nearly synchronized larvae emergence. This is not really necessary. Most females will deposit the bulk of their eggs the first night, with smaller and smaller numbers on subsequent nights over a five to seven day period. Expect 250-350 eggs from most females, as many as 500 from larger individuals.

I do most of my rearing outdoors on sleeved branches or entire trees. Sometimes I will leave a female in a single bag and then transfer the entire bag of unhatched eggs to a sleeved host a day or so before I expect the first larvae to emerge.

In the airy sleeve I do not have to worry about carbon dioxide buildup or condensation problems. The newly hatched larvae just crawl from the bag (torn open, egg side down, taped to branch inside sleeve) onto the stems and foliage. If the forecast calls for rain, I will sometimes tape foil paper to upper surface of bag.

Avoid putting wet foliage in with larvae. If you gather leaves that are wet (it's raining and caterpilars need food), dry the leaves off (pat them dry) before offering them to the larvae. If you gather foliage on a cool spring morning/evening, the cold leaf will offer a surface for condensation. This is not good in a closed container. Let the foliage first warm to room temp and then pat off excess moisture (dew) before offering to the larvae.

Once your caterpillars have started feeding, you just need to make sure their rearing container is kept clean and that they have fresh food in an environment that is neither too dry nor too wet. A tightly lidded indoor container with no airholes will usually avoid problems with indoor air which could be too dry. Making sure foliage is dry before offering it to larvae will usually avoid problems from excess humidity.

Sometimes you will see caterpillars crawling around with their egg shells still covering their anal claspers. As they move onto foliage and crawl around a bit, the remaining shell will usually dislodge itself. Sometimes I dislodge the shell with my finger nail, but I have never seen a caterpillar perish from this initial and usually very short term "problem".

Happy pillaring!

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