My experience with raising monarchs has been that, early in the season, mid-May through June, the milkweed is generally free of pathogens, and chances are good that healthy adult monarchs will eclose and fly. In July, August, and September, it is much harder to raise a healthy monarch. I have had some success by rinsing milkweed leaves in a strong stream of warm water, at the kitchen faucet. The leaves must be dried off before they are given to the caterpillars, it would not be good to increase the humidity in the rearing container. Also, I raise each monarch cat in an individual one quart glass jar, with fiberglass screen on top, held down with a rubber band. They can socialize with other butterflies when they grow up, when they are in the caterpillar stage, the only socialization they have is with me. I might raise 10 monarchs per year, so far this year I have raised and released 6, and lost one to disease. I am not sure if the pathogens you are dealing with are in the egg, or on the leaf. Washing milkweed leaves does help, in my experience. All of this individual attention takes time, so the numbers that are raised & released is much reduced.

You didn't say what you are dealing with.

Heat is a DEFINITE factor at this time of the year. As Eric mentions, moisture (humidity) is very bad and when coupled with heat, can create a lot of the problems right now. His idea of raising the larvae individually in screened containers is great!

Keep in mind that in the wild, it is lucky if even 3% to 5% of the eggs laid make it to adulthood. I've been revising my Monarch site based on the various questions I've been receiving this summer. Check and see if what you are experiencing has been included.

Here is a link that might be useful: Learn about Monarchs

What I am dealing with:

When the caterpillars get to the third instar, they stop eating, they go limp, and die. They look kind of shriveled up, and the top half of the caterpillar will droop over. The color doesn't change. When I remove the caterpillars, it's like "loose skin"; it's like they've starved and died from the inside out. The caterpillars are usually on the leaves when this happens, so they are not off molting.

The heat here has been absolutely horrible--we've had 15 hundred+degree days with high humidity. However, I'm raising the caterpillars inside at 78 degrees.

I have a new batch starting to hatch out today. I thought they weren't going to make it--they've taken longer than usual--but I see the little dark heads in the eggs. We are down to the 90s this week. I did have 4 males eclose in a paper sack this morning. Haven't released yet as I want to check them out. I've got about a dozen that are close to pupating that are in paper sacks and doing well. But, I also found 2 cats that I had isolated had died this morning. Once I get the cats up to the final instar and put them in the paper sacks, I usually have no problems--chrysalids are healthy.

My food is homegrown. I've tried several different types of milkweed, and am now feeding only tropical. I read that Incarnata can cause problems. My incarnata is sad looking this year--don't know if finding a lot of the eggs on the incarnata could be a factor. I also had a lot of eggs on my physocarpa. The caterpillars that have died came from eggs harvested off of these plants.

I'll keep trying until I figure this out--just hopeful someone has dealt with this and has an answer.

I think it was 3 years ago that I dealt with Black Death. And that went back to the incarnata plant that was getting chlorinated water from our aerobic septic system.

Sandy

Btk the pesticide they use for gypsy moths does this to caterpillars.

"From: Waite Park, Minnesota
Kimball Elementary School
Q: Why did so many of our caterpillars die this last fall from the monarch lab...we only tagged 25 of our 200 we received and were really sad...........we washed hands, etc. to avoid parasites but can't figure out what it was. Thanks, Karen. Hope all is well with you. Did you go to Mexico this winter? Paulette Hauge 6th grade teacher at Kimball Elementary School!

A: Hi Paulette! I did go to Mexico this winter, and was thrilled to see that the colonies were larger than they were when I was there last year. It was an amazing trip, since I was there just before they left for the US, and were, therefore, very active.

We did have problems in our lab last year, and you should receive our newsletter with a discussion of this very soon. Here is a brief summary: We have come up with two possible reasons for this. The first is a microsporidian disease called Nosema. This is a widespread group of organisms that are found in many insects, and there is a group within them that infects Lepidoptera. They are spread very easily, and are extremely contagious. WeÂre not sure where the infection came from, but it is sometimes used as a biological control agent to combat insect pests, like corn borers and gypsy moths. One report said that Nosema is sometimes used to control greenhouse pests, and may have even been in the potting soil that we used. The second possibility is something called nuclear polyhedrus virus (NPV), which would cause them to turn black and sort of gooey. This is also used as a biocontrol agent, and is airborne and especially common in the fall.

Both of the above diseases are very contagious, so would have spread quickly from larva to larva. Please assure your students that there is nothing that they could have done about this disease, and that they did nothing wrong. It's like a disease that spreads through a human population that has no known cure. Additionally, assure them that neither of these diseases can be transmitted to humans!"

Here is a link that might be useful: 2006 Questions being Answered by Dr. Karen Oberhauser

Thanks, Runmede. I will do some research on the Nosema angle, as I do think I'm dealing with a disease/virus. The plants that I collected the eggs from have been in my garden all season. I do live near lots of soybean fields and sod farms which I'm sure use pesticides, etc. I haven't seen any blooms on the soybeans yet, so can't imagine the Monarchs visiting them. I can't know where my Monarchs that come into my yard have been before they get here, or what they may be exposed to. I can only try to monitor what happens in this yard.

In the meantime, one more isolated larvae died. I collected 40 eggs this afternoon while out gathering LFP for my remaining caterpillars. 18 of the eggs I collected at the end of last week have hatched and about 6 more are ready to hatch. These will go to a friend to raise. It will be interesting to see if these make it on her milkweed. I have another dozen that should hatch in the next day or so. And I found 6 caterpillars at different stages that have been put in separate containers.

Sandy

I don't think that Gypspy Moth populations have reached Oklahoma yet, in significant numbers anyway. There may have been an isolated population, but I understand these are usually eradicated quickly. Have you heard of any, Sandy? I think the BTK is the BT kurstaki that is frequently used to kill caterpillars because several folks have spoken about it on the Oklahoma Gardening forum and its use against the Tomato and Tobacco Hornworms in particular.

Sandy, I'm wondering if our weather has not had a really bad affect on the Monarchs this year, and possibly other larvae. The heat trend we've experienced began in mid to late May, much, much earlier than usual, and on top of that it was accompanied by very high humidity across the state. This trend has continued all summer long and has only broken this week. Anyway, this heat/humidity is not an environment conducive to a healthy Monarch population since humidity is literally the kiss of death. We've had a lot of plant disease and extreme insect populations in conjunction with these conditions.

I have 8 chrysalises now, and 2 or 3 babies in my cage. So far, so good. But I haven't raised the numbers you have either. The aphids are so bad on the milkweeds, too, that I've been rinsing them off every other day. The honeydew they exude makes the foliage very sticky and probably open to all sorts of problems.

Have you tried the bleach wash that Tdogmom recommends on the foliage? A pain, I know, but it might work unless it's something systemic in the eggs or the plants.

What a problem. My heart goes out to you and I hope you find a solution.

Susan

Sherry, your Monarch learning website is much improved from a few months ago--no more horizontal scrolling. Everything fits in a 1280 pixel screen.