Back in September 2011, we did a blog story about raising Tobacco hornworm (Manduca sexta) caterpillars. The stunning blue caterpillars were fun to raise and did well for us. When they pupated, we carefully placed each one in a hollow drilled into a piece of hardwood, which simulates their natural instinct to burrow into a small place during metamorphosis. A few weeks later, we enjoyed the one moth that emerged from pupation.
The other pupae were less forthcoming. After a month of waiting, we moved the pupae out of their dedicated exhibit cage. There are few sights more boring than a cage with a piece of wood in it, and no evidence of life. Instead, the pupae were moved in with the stick insects, where they spent the winter and the first part of spring.
But on April 16, we came in to a little surprise. One of the moths had emerged at last! The change in day length probably stimulated her to complete her transition from pupa to adult. Many insects overwinter in the pupa stage, as a way to avoid the worst temperature drops and the lack of food the cold months bring. The ability to suspend development until the correct environmental cues occur is called diapause. For those who enjoy scholarly articles, we include the following link http://jeb.biologists.org/content/91/1/331.full.pdf, one of many for this species whose diapause has been closely studied.
Our new moth is now flying in the Tropical Butterfly House. Though neither tropical nor a butterfly, she seems to enjoy the warmth, space, and abundant flowers. Perhaps other Manduca moths emerging from diapause will soon join her.