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 for the input coolbutterfly and terrene. Unfortunately I'm not around for most of the summer thus not able to help the monarchs here. I found a couple of Sphinxes that had been parasitized but maybe by a different species of fly as the caterpillars died before they ever entered the chrysalis stage. I've actually never seen so many monarchs here (not a huge no. but a relatively large no. for this place). My daughter and I planted some A. tuberosa's (Hello Yellow),,,maybe that helped :)! Funny thing is I know the caterpillars need Asclepias sp. plants and we put in some Monarda and we have lots of goldenrod, chelone and Joe Pye fot the butterflies but you know what is always the wings down favourite?! That darn thistle!!!!!! Anyway, I like to think that some caterpillars survived and at least we're providing some food sources for the Fall migration...every little bit helps :)!

Terrene, what kind of cage do you raise your monarchs in? Years ago, we had one summer where I though we had our first disease outbreak. we had always raised our cats in plastic ice cream buckets. Well, it turned out the bucket we used that year was toxic! The second we switched to a glass container all the sluggish caterpillars suddenly perked back up. Now I have two cages: This was my main cage this year. it works well except for when the caterpillars are in their first few days, they can crawl through the mesh: (so I put the wee ones in a glass bowl with paper over the top...only lost 1 adventurous cat this summer) http://store.discovery.com/detail.php?p=86231&v=discovery_toys-games_type_animals-bugs I also got another cage for next summer. I plan to put potted tropical milkweed plants and raise TONS of butterflies in a mini greenhouse: http://www.amazingbutterflies.com/butterfly_castles.htm I had one strange occurrence at the beginning of the summer. The first two monarch eggs I brought in off the tropical milkweed turned completely black so I just tossed them after a couple days. Nothing out of the ordinary after that. Here's to healthy cats and butterflies in 2011! Tony

Susan, As always my thoughts are my opinions based on many years of actually doing, not just accepting what others say. So they are only FWIW to be taken as a person chooses to take them. IMO common logic dictates that like with most infestation, disease or infection, the level they intrude an individual at can vary widely from minor to massive. That is commonly proved out with OE in Danaidae. If a larvae makes it through complete metamorphosis to an imago that can eclose and form OK, even if OE is present it was a relatively minor infestation in that individual. The opposite being if a larva at any instar, pupa or adult that has OE dies without getting through complete metamorphosis, that individual was obviously infested at a much higher level. Unfortuanately no matter at what level (with OE especially), failure to destroy any sick livestock whether it be OE, another parasatoid, viral or bacterial infection in most cases will promote the spread of any of any of them to other individuals. OE is the prominent one that will carry on to generation after generation beyond a given brood, and nothing but complete elimination of any brood within your control that might be infected with it will help slow it down in a colony. Why in my opinion when it comes to livestock even suspected of possibly having OE it's not worth taking any chances with them "for the good of the species as a whole". For those of use who did/do field work with Lepidoptera, that includes wild Danaidae livestock found or adults netted that show any possibilty of hosting OE. NOTE: Even if you have a very strictly controlled gardening and rearing rigime (which I doubt any of you have), you won't eliminate all of any OE present. So don't go slap happy destroying everything in sight. Instead be analytical and logical, and then decide what is reasonable for your own circumstances. Yes, livestock can have OE and not show any of the so called "visible" signs of it, which IMO are not proof positive of OE anyway and can be from other causes. In part why on my OE thread I offered some habit and condition factors that could also suggest OE is present as well even though they also do not prove OE and can also be from other causes. Bottom line, to prove OE is NOT present in an individual for certain takes a microscope or loupe. And in almost all cases if a larvae it will have to be euthanized to test with any certainty. A possibility to check for OE in pupa is to test the purge of the last instar larva for OE, but unforunately that is not 100%. I'm a lot more scientific in my appraoch to Lepidoptera than all of the folks here, so I don't accept things at face value. I am also skeptical of data from other sources that are not proven to me. The Internet and publications commonly breed misinformation about everything, including Lepidoptera, that is passed on by ACE's who probably got it from another one. So it's prudent not to trust every thing you read on the Internet or in books if it's not from a source you trust. Larry