Posted by Margaret Dominguez on October 7, 2007

Q: We found some Eastern Black Swallowtail catterpillars on our dill and parsely plants and put some plants and caterpillars in a 10 gallon aquarium (dirt on the bottom). Many of the caterpillars buried themselves in the dirt after a while. Did they die? This was in mid-Sept., but I thought they overwintered as a chrysalis.

There is a tersa sphinx moth pupating in the tank, as well. Will it eventually hatch or do we need to put the tank outside for the winter?

Habitat: suburban/yard

State: Texas

Habitat: suburban/yard

A: You're correct that the Black Swallowtail larvae should pupate as a chrysalis above ground. I'm a bit confused myself why the caterpillars would go underground if they have food to eat. This species overwinters in the pupal stage (chrysalis) so once they're finished growing as caterpillars, they should attach themselves to plant material and make that transformation.

To avoid having any of these animals emerge too early, you are correct in thinking they should be kept outside. Not necessarily beyond the house but somewhere where they will receive cold temperatures such as an unheated garage. I could believe too that day length may play a part in their development so maybe somewhere they'll get natural sunlight (not direct sun). Any time wild animals are kept, it makes sense to duplicate their natural environment as closely as possible to make sure that something important isn't missed. Too often people with the best intentions harm an animal because they thought it needed to be kept warm, for example. Good luck to you and I hope this helps you out a bit.

John Wiessinger ( October 8, 2007)