Two sphingidae caterpillars; advice?

[norwegianblue]

Hi folks,

I was out with my daycare class, and we've found what I think is a Great Ash Sphinx caterpillar. I also found a bedstraw moth caterpillar. Both pupate in the ground.

I've got a caterpillar cage that I'm using for a Polyphemus moth, and I'm going to leave it outside over winter.

What I'm wondering is this: If I put a potted lilac plant in my caterpillar cage for the sphingidae caterpillars to hang out on, can they pupate in the potted soil and survive the winter?

[pennswoods]

It's quite possible they would do OK. If you live in an area where it will get extremely cold, far below freezing for long periods, it might not survive. Too many variables and unknowns to just say yes or no.

The sphinx moth caterpillar will give you indications that it is ready to pupate. It will most likely evacuate it's digestive tract, then leave the host plant and go walkabout for a day or more. This means it has been triggered to pupate and is searching for a site to dig down. I've had good success placing such larvae in a 5 gal bucket filled about 3/4 full with moist potting soil and letting them dig in when they are ready. I've also had good luck with other ground pupators by placing them in a large plastic box with damp (wetted then thoroughly squeezed out) shredded paper towels, place in COMPLETE darkness for several days or a week. Give the larvae plenty of time to pupate and for the pupa exoskeleton to harden. Then you can move them to whatever container to await eclosure. If you let them dig down in the dirt, just leave them alone, don't dig them up. Keep the soil moist but not wet, and keep the container in a sheltered location where it won't freeze to a solid block of muddy ice.

[oehlkew]

I agree with Pennswoods, but the presence of Hyles gallii does suggest you are in one of the northern US states or in southern Canada. It may be too cold and dry for them to survive outdoors over the winter in potted soil.
Many people find mature Sphingidae larvae, crawling on the ground, quite a distance from their natural host plant. I would be concerned that the larvae might not "understand" that you wish them to pupate in the lilac plant pot. They might "hop the fence",
looking for greener pastures. What are you going to do to make sure they do not escape as larvae?
If you are going to leave them outside over the winter in soil, exposed to natural elements, you need to make sure there is drainage in pot so they do not drown in an accumulation of rain and melted snow.
You also need to make sure that they do not desiccate from a lack of moisture.
I recommend letting them pupate in small tubs or buckets with
no soil or pupation medium, just a paper towel lining the bottom of the tub. I do not shred the paper towel and I do not moisten it initially.
I usually use sandwich sized, plastic tubs, like tupperware or Galdware, put a single, folded, paper towel on bottom of tub, insert the mature larvae that have stopped feeding, and then put the lid on tight with no airholes. You can put both larvae in the same tub.
Larvae will sweat and shrink quite a bit and the paper towels will become quite moist from the moisture given off by larvae. The abdominal legs will become quite stumpy, and you may even think the larvae are dead before they pupate.
I currently live on Prince Edward Island in eastern Canada.
My Sphingidae of Canada page is at
www.silkmoths.bizland.com/SphPEI.htm
You can see my own scans of pupae of Sphinx poecila, Pachysphinx modesta, Paonias excaecata, Hemaris thysbe, Amphion flordensis, Darapsa choerilus, Hyles gallii. All of these images came from reared larvae that pupated in tubs with nothing
more than a folded paper towel.
I have also reared the other Sphingidae species found on PEI and have had success with their pupation, overwintering and subsequent spring emergence using the methods described on those pages.
My Sphingidae of the Americas page is at
www.silkmoths.bizland.com/danjansphinx.htm and there are links from that page to US Sphingidae where all US states are covered, to Canadian Sphingidae, and to all countries in North America, Central America and South America and most of the islands in the Carribean. Most of the Canadian provinces and US states now have larval thumbnail checklists which should help you id your larvae and adult moths.
I use the same technique for Saturniidae larvae from subfamily Ceratocampinae and have had great success with all that I have reared: Anisota virginiensis, Citheronia regalis, Citheronia splendens sinaloensis, Dryocampa rubicunda, Eacles imperialis,
Eacles imperialis pini.
The paper towel in the initial setup will get quite messy, and I often have as many as a dozen of the smaller species larvae
pupate at same time in same tub, usually just four or five of the larger species in same tub.
After pupation and after the pupae have darkened and shells have hardened, I inspect pupae and overwinter them, sometimes as many as thirty pupae to a single sandwich sized tub with a slightly moistened, fresh paper towel on the bottom of the tub.
I put a layer of small-bubble, bubble wrap over the damp paper towel on bottom of tub, put a folded paper towel atop the bubble wrap, and then lay the pupae on top of the dry paper towel and then snap the lid on tight with no airholes.
I overwinter my pupae in one of the crisper drawers of our refrigerator. If that is not an option for you, you can overwinter them in the tubs in a cool basement or in an unheated garage or outdoor shed. Good idea to keep tubs near floor if in garage or shed as those sturctures can become quite warm even on a cold winter's day. Once a month, open the tubs just to make sure the
paper towel on top is still limp from absorbed moisture. If it is dry and stiff, the container needs a few drips of water added. A dry stiff paper towel indicates you are losing too much moisture, and pupae will also desiccate (dehydrate) if additional moisture is not provided.
I like to document Sphingidae, Saturniidae and Catocala sightings and would appreciate if you can provide digital images with data,
i.e., at least date and location to county level. Hope you have success whichever method you choose.
Use unscented paper towels with no colour or dyes.
Bill Oehlke

[pennswoods]

I have a Eumorpha pandorus caterpillar which just today did the "evacuate and leave" routine. I put it in a plastic container per Bill's recommendation (dry). I trust Bill.

We've done this enough to know there are never any guarantees of success, no matter how careful and prepared you are. Hoping for the best, because this is the first sphingid we've worked with in quite a few years!