I put this in my response to Valerie, but I thought I would post it as well. We just had a strange occurrence happen that we’ve never experienced before, at least not at this high of ratio.
Leecy and I took in about 7 Monarch Caterpillars about a week ago. Only 2 of them made it to Chrysalis, the rest of them are just “dangling” straight down (not in a “J” shape). I don’t know if they had OE disease or perhaps were attacked by the Tachinid Fly, or maybe something else.
UPDATE: It’s probably from the Tachinid Fly. See this link for the gory details (the fly larvae eat the Caterpillars from the inside out).
For folks who just recently started reading my blog, I have posted about parasites and diseases in Monarchs in earlier postings. Besides the information that I posted previously, Valerie also has an excellent site about Monarch Butterflies and their diseases and parasites and goes into much more detail than I have. If you’re curious about raising Monarch Butterflies (and the hazards that can occur), I would definitely recommend checking out her site as well. You can find it at Evanson Art & Design.
I just took some pictures of what I was talking about above. First, are the dead Monarch Caterpillars. I’m pretty sure it’s because of the Tachinid Fly. If you look closely at the images you can see that white string coming out the Caterpillars. The Caterpillar on the far left is starting to liquefy.
Monarch Caterpillar Disaster
This image shows those “strings” protruding from the Caterpillars. You can also see that the Chrysalis is starting to have problems as well.
Caterpillar Carnage
Here’s a closeup of the Chrysalis from the photo above. It’s turning brown after one day, which is not a good sign. You can also see a “string” from this Chrysalis as well.
I ended up destroying (if they weren’t dead already) all the Caterpillars and Chrysalis from these images (tossed in a ziploc baggie, thrown in the freezer).
Closeup Of Monarch Chrysalis Parasite
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by texdr
3 comments
texdr - I thought it was pretty difficult to feed Monarchs a synthetic food? Maybe they have some secret recipeSeptember 7, 2009 – 5:05 pm
Valerie - Monarch Watch just updated their Facebook site in regard to the baby food containers. They raise the caterpillars in there only. After pupating, they move the chrysalises to an emerging chamber that has room for them to expand their wings. They are feeding the caterpillars an artificial diet of their own making. Hm, wonder what the recipe is . . .September 7, 2009 – 4:21 pm
Valerie - I’m voting you’ve been hit with Oe. Flies would have produced at least 1 pupa per caterpillar. I’ve lost over a dozen this year to flies (a tachnid fly got in the house — the cats let me down) and most of them became chysalises first. Could be a virus too. This year I’ve lost many caterpillars with the similar symptoms to yours. The ones from those containers that became butterflies were very weak, had split proboscises and showed Oe under the microscope. I’m not seeing alot of spores, but the effects are devasting. Been doing alot of bleaching. Monarch Watch just posted a Tweet that says they are looking for plastic baby food containers. One container is big enough to house 1 caterpillar. They say it’s working great. Looks like they are feeding some type of synthetic or prepared milkweed, though. http://twitter.com/monarchwatchSeptember 7, 2009 – 4:05 pm