The chamber is formed as the larvae thrashes around a bit and sweats off excess moisture. The moisture from the sweating and the compaction from the thrashing serve to cement the chamber walls. Larvae which are not going to diapause (hibernate) for the winter, sometimes spend less than two weeks in the chamber; larvae of other species may spend several fall and winter months in diapause before emerging the following spring or summer.

The pupa in Cristina's picture has just shed its caterpillar skin and is quite soft and a greenish yellow colour. The pupal shell usually hardens and turns brownish within a few hours.

Most people who have turned soil in a garden have encountered moth pupae at one time or another. There are other moth families and subfamilies whose larvae pupate underground.

Cristina writes, "This is the set up we created for our last sphinx moth guest in 2008 ... as you can see, that one was a success. We actually fed it for about a week before it pupated. That was good, because it gave me time to research it, and it was during that time I learned some caterpillars pupate underground - WOW! Did we learn something new! As you can see, we were absolutely blessed that after completely rearranging every speck of dirt in his habitat, that he (or was it a she - the moth that emerged had club-shaped antennae) decided to pupate right up front where we could watch the whole thing.

"The dates for that "sighting" are on the pictures if you want to update the White Lined Sphinx moth report on your web page, and, yes, you are more than welcome to use my pictures.

"Well, we've completely lost sight of our current guest (Eumorpha achemon larva, August 2010), so we'll just have to wait and see where he/she settles. Can we expect a similar length pupation? The last one was almost exactly a month."

I replied, "Recently I have received reports of Eumorpha pandorus moths (close relatives) emerging from pupae within two weeks of pupation, but they were from the southeastern US where it is considerably warmer with a longer "growing season". I do not know if the moth will emerge in just a couple of weeks or if it will be in a diapausing (hibernating) state, and not emerge until next spring. Much depends upon temperature and length of daylight photoperiod that the larvae experience as they near maturity.

"I also notice what might be some parasitoid wasp/fly entry wounds (little black dots) on some of the thoracic segments of your Eumorpha achemon larva. The spots may be flecks of dirt, but if a parasitic wasp or fly deposited eggs on the surface of the caterpillar, and the parasitic larvae burrowed in, then no moth will emerge from this caterpillar, even if it does pupate successfully. Some parasitoids have a long ovipositor that they insert into the larvae, enabling them to deposit eggs internally. This process also leaves a surface scar on the caterpillar larva. Hope your larva does not have parasites, which are specific to larvae and not to humans."

Eumorpha achemon fifth instar, Cheyenne, Laramie County, Wyoming,
August 27, 2010, courtesy of Cristina J. Sheats.

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