Catapillars dying

[cmason]

I know this has been discussed before, but it seems like all of a sudden I'm having a hard time getting the catapillars to become butterflies. Many cats die at various stages and lately when their in a crystal stage they become liquidy and nothing happens. Is this a parasite problem or am I raising too many in a container. I'm using aquariums and large pretzel containers.
Chris Mason
Lake Geneva, WI

[Mona Miller]

Crowded conditions can cause problems. In my Glad containers which are 13 cups, I've been raising 4-6 caterpillars. The larger 4th-5th instars that I bring in, I've been raising those in separate cups.

Many people have been having problems and I think some of it is (nuclear polyhedrosis virus) NVP and Nosema. A chrysalis that gets dark could also be OE.

Best thing to do is get rid of the sick caterpillars/pupae, bleach, rinse thoroughly and start over. If you have caterpillars that are not acting sick, then put them into a separate, sterilized container and don't over crowd. I know its hard not to take in every caterpillar, but you can't raise them all. I've got caterpillars outside and I've got caterpillars inside.