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If you're sure they're not just hanging out somewhere to molt, in which case they will return after a day or two, they are being predated by something. I have had both wasps and jumping spiders take my caterpillars. My recommendation is that you take at least a few caterpillars and raise them inside in containers where they will be safe. Don't put more than one in a mason jar or two or three in a larger container, because they get stressed if they are crowded.
This is the monarch disease, OE. If you see chrysalises that have green and black spots, destroy them (the least stressful way is to put them in the freezer overnight). If the butterflies are having trouble emerging from their chrysalises, or their wings do not fully expand or dry out curved or crumpled, those are also infected with OE. Please euthanize those butterflies--again, the freezer is best.
OE is not caused by anything you've done. It's passed on by adults to the offspring. You can read more about it here: OE spore .
I have had years where most of my caterpillars were infected with OE, and years when I hardly saw it. This has been a good year. Fewer caterpillars altogether, but they have all seemed to be healthy.
If your milkweed was toxic, you'd actually see dead caterpillars. I think the milkweed is probably fine.
I hope this helps!
By the way, I heard recently that the drought affecting California has actually been GOOD for monarchs, as more people are planting native, drought-resistant plants like milkweed. I was able to buy some nice plants from a vendor at the farmer's market who usually only has common garden flowers and vegetables.
(last paragraph)..........I just read an AP article in our Sunday paper this morning as to how the planting of more milkweed due to the California drought is helping the Monarch butterfly.
If you're sure they're not just hanging out somewhere to molt, in which case they will return after a day or two, they are being predated by something. I have had both wasps and jumping spiders take my caterpillars. My recommendation is that you take at least a few caterpillars and raise them inside in containers where they will be safe. Don't put more than one in a mason jar or two or three in a larger container, because they get stressed if they are crowded.
This is the monarch disease, OE. If you see chrysalises that have green and black spots, destroy them (the least stressful way is to put them in the freezer overnight). If the butterflies are having trouble emerging from their chrysalises, or their wings do not fully expand or dry out curved or crumpled, those are also infected with OE. Please euthanize those butterflies--again, the freezer is best.
OE is not caused by anything you've done. It's passed on by adults to the offspring. You can read more about it here: OE spore .
I have had years where most of my caterpillars were infected with OE, and years when I hardly saw it. This has been a good year. Fewer caterpillars altogether, but they have all seemed to be healthy.
If your milkweed was toxic, you'd actually see dead caterpillars. I think the milkweed is probably fine.
I hope this helps!
By the way, I heard recently that the drought affecting California has actually been GOOD for monarchs, as more people are planting native, drought-resistant plants like milkweed. I was able to buy some nice plants from a vendor at the farmer's market who usually only has common garden flowers and vegetables.
I keep a daily log which includes a day-count-number for each chrysalis and its condition and a caterpillar-count for caterpillars found (recording what each is doing, where it is, how big/small it is). I also note whatever else I see in the vicinity of the milkweeds (anoles, any crawling/flying insects, butterflies, evidence of chewed leaves on the milkweed or on the other plants in the garden, etc.). {Side note: while I'm out with my dog while he's doing his thing (which is investigating every blade of grass), logging info is a great way to occupy my time :-)} Since I find no hide-nor-hair of caterpillars the next morning, I'm guessing there's a predator having a good nighttime meal.
I really appreciate all the info about OE ... I now assume that's the issue. I've not seen any monarchs in the past days (no eggs, no caterpillars, no butterflies), so perhaps with fingers crossed the cycle might end. Should any caterpillars appear, not sure how unless eggs have been laid on something other than milkweed, I do have a box that is set up for butterflies and I can at least protect the caterpillars from predation and hope they aren't infected.
(last paragraph)..........I just read an AP article in our Sunday paper this morning as to how the planting of more milkweed due to the California drought is helping the Monarch butterfly.
A few organizations in our area (southern Oregon) have been coming up with creative ways to contribute to the Monarch populations.
That seems like a lost cause since Oregon and Washington both spray with BTK to control the Gypsy Moth infestation which threatens agriculture and forest products.
BTK is based on a bacteria that is not toxic to humans and most animals, but is toxic to all caterpillars regardless of what kind of moth or butterflies they may become.
I just noticed last year how absolutely void of life my suburban backyard is. The most activity youll see is a squirrel here and there and maybe a pidgeon. Its a far cry from what Florida used to be...
On another forum I read, I've learned that the monarch populaton increased significantly in Mexico this year. In fact there was a video showing a huge cloud of monarchs in one region.
So, things are looking up for Monarchs - this year, anyway.
I have been planting milkweed for the last 3 or 4 years. Have released many butterflies. The only place I buy my milkweed is the nursery that I know doesn't use pesticides. Never buy from the big box stores as they are treated with pesticides. Tropical milkweed is the most common here in SW Florida but read up on a butterfly disease called O.E. It causes deformities in their wings.
I never plant mine in the ground as they would be completely bare in a matter of days. After they have a lot of cats on them, I bring them into my covered screened lanai so they can eat, grow fat, make their chrysalis and then emerge. When their wings are dry and they are trying to fly I let them go outdoors as long as they can fly fairly high.
I keep about a dozen plants and rotate them in the lanai and outside so the monarch will lay their eggs. As soon as they have eaten a plant completely bare, I cut the stems back a little and they regrow pretty quickly.
I 'fostered' a monarch butterfly cocoon once. I found it. I knew it was a cocoon, but not what kind, so I looked it up. I found out it was a monarch, and set it up for success, and watched.
Their cocoons are so pretty! They're kind of an opaque jade green color, and the 'zipper' (that they break out from) is gold. Not like "gold color". It looks like the metal, gold. I mean, really...that cocoon looked like a piece of jewelry.
So I taped the cocoon to a stick, and stuck the stick in one of my flower pots, so it'd have a soft place to land, in case for whatever reason, it fell before it's wings dried.
One Friday, the cocoon wasn't opaque anymore, and I could see the butterfly. Went to the country that day, and when we came back that Sunday, it had hatched and presumably moved on.
I guess I should call them chrysallis...not cocoons. Look them up...so pretty!
Many gardeners here are actively planting milkweed to support the monarch butterfly.
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