Split-skin chrysalis

[skates4marty]

Hi Folks

In 5 years and almost 500 chrysalides, I have never seen this (see photos, but beware: it hurts to look at them). The first I found on the floor of the cage. That makes me think it was newly formed and fell during the last wriggle, but that is just a guess. (Until this year, I kept a map of each J with the date, but this year has been out of control [after getting nothing in the spring], and now I am just counting B's when I release them.)

I found a second one today, hanging normally, but with the split skin. I have no idea how old it is.

They are being raised in the dining room, as usual. All conditions the same, except more crowded this year.

Also this year, it seems more times than usual the last shed skin has not dropped to the floor but stays at the top of the C, as in the second pic. Related?

Theories?

[Mona Miller]

http://www.evansonart.com/monarchdisease.html
This website has some good pictures of problems that can happen.

Crowding can cause problems. Other caterpillars silk wherever they go. If silk gets caught on the caterpillar that is changing it can keep the caterpillar from pupating.

[skates4marty]

My friend who will raise over 200 this year also had 3 split-skin C's. She lives 10 minutes away, and I have not seen her since the season started, so it can't be that we passed an infectious agent. And last night, a chrysalis in a critter cage with only 2 others fell to the floor. There is a little hole in the top and it is hollow! But still green. And hard. The other 2 whose photos are posted above are still green.

Is no one else having these weird chrysalis problems?

[Mona Miller]

Plenty of people are having weird chrysalis problems. Did you look at the website that I posted? Empty chrysalis could be a wasp or fly problem.

[skates4marty]

Yes, thank you, I looked on that web site (and posted it to our group's Facebook page), and my C's look a little like D5 but they don't have the black spots. And they are not deteriorating. Together, my friend and I have seen over 1,000 C's over the years, and this is the first year we've seen this split-skin problem. Though you do get those outliers. A couple of years ago, I had one cat infected with Beauvaria bassiana (the mummy disease). That took me a while to find on the internet.

[Mona Miller]

We haven't seen weather like this either. I'm not looking forward to another mega blizzard in the DC area.

All we can do is:

1. Try to find out what is causing this.
2. Try to raise healthy Monarchs by giving them fresh food and a clean cage.
3. Keep doing number 1 and number 2.

[skates4marty]

If the general mortality rate in this crazy hobby were 30%, I'd just shrug and say, "There goes another one." But we home-raisers get used to a very high survival rate. When one doesn't make it, I think, "What?? You're dying? How can that be?" Then I have to remind myself, "Look at all the healthy ones."

[applestar]

I had one chrysalis with a small round hole. The internal liquid bled out of it and the chrysalis died. I suspect one of the older cats nibbled on it.

In your photos they do look like scratch marks don't they? ...or that the chrysalis surface was not strong enough to sustain the internal/growth pressure-- kind of like stretch marks on a pregnant woman's belly. ...kind of like tomatoes that split after heavy rain. Could low humidity cause the chrysalis to dry out too soon, losing elasticity?

I was recently wondering if the excessive drought in my area could have changed the concentration of phytonutrients -- as well as environmental toxins -- in the milkweed. I'm glad to be feeding them out of my garden where most of the milkweed are looking very healthy. Someone told me she's having trouble finding any good looking wild milkweed at all. I'm concerned for the wild population of Monarchs....

[Mona Miller]

I've noticed that it appears that after they molt that there is a secretion that then hardens. Perhaps something keeps this from happening.

Often I've read about the caterpillar getting tangled in its own silk or the silk of another caterpillar.

[Schmetterling]

Did these split skin chrysalis ever enclose? I had a similar looking one, it enclosed today with a crumpled wing and a dead fly looking bug on the effected area. This b will never fly, so is freezing the best way to euthanize. Next year I will test, but this doesn't appear to have symptoms of oe.

[Mona Miller]

OMG, it is up to you. Either put it out on the nectar sources, or freeze it. Hard call. Sorry.