Did you sterilize the containers that you raised them in? I used a weak bleach solution to sterilize my containers and let them air dry before use. That is too bad none of them eclosed, last year I raised 839 Monarchs, my most ever. Probably have to scale back some, as it was lots of work.

No, I didn't sterilize. I use a 10-gallon aquarium. This year I'll do some serious cleaning before the season starts. It's so disappointing to have huge, healthy caterpillers that never emerge. I feel so responsible for their deaths!

Thanks for the suggestion!

There may not be enough ventilation in the aquarium. I made my cages from plastic containers from Sams, bought cheese balls, pretzel sticks, biscotti. I cut out 3 of the sides, partially, leaving the corners of the container and caulked screening material to cover. Allows plenty of ventilation and they are very easy to clean/sterilize. Hope this helps.

Mechelle

I had the exact same experience last season. Black Death was horrible. We've had great success raising butterflies in the past, but the extremely wet weather (I believe) contributed this problem. I did keep a very clean environment in my aquarium and even reared some in their own containers. Sadly, the outcome was the same. I've never had an experience like the one from last season.

Here is a link that might be useful: My Garden and Butterfly Blog

Hey, remember that they dehydrate too. If they are indoors with the air conditioning or heater without a living plant nearby, they often color up and die overnight. They weigh as much as a cotton ball when they're dehydrated. If you think this could be the cause, just add a damp paper towel to the aquarium and add a bit of water to the towel every day when it dries. Too wet is super deadly but too dry is also.

I will certainly sterilize the containers. I don't *think* they were dehydrated--I keep stems of milkweed in little plastic straw cups without the straw. (Those "take and toss" cups...using the straw hole for the milkweed.) I would think that would stay pretty moist.

I hope it's not a ventilation problem. I like the aquarium because the pain-in-the-butt cat might claw at anything with screening.

It was so disappointing compared to the previous season which was 100% successful! The caterpillars are just so darned cute--I hate to feel like I'm killing them somehow.

We will try again, and perhaps this will be a better season.

Season before last we had tons and tons of red admirals; last season they all had that parasite.

Maybe last season just wasn't a good one for us and this one will be better!

Thanks for your advice!
Elizabeth