Rearing monarchs: Is mortality lower than in the wild?

[Jeff Serena]

Newbie post. . . . My daughter and I collected 33 monarch caterpillars this year. We worked conscientiously at raising them well, but we released only 28 healthy adults. Two caterpillars quickly turned black and died, one caterpillar died without first turning black, one made a small and poorly formed chrysalis and died, and one normal-appearing chrysalis turned black and died. Is that an unusually high mortality rate? Would the mortality rate likely be higher or lower if we'd simply left the caterpillars where we found them?

Thanks in advance for any advice and insight.

Very best,

Jeff

[dandjtaylor]

Jeff

Actually 28 out of 33 (85%) is not bad at all for reared 'flies. In the wild, it can be as low, or even lower than, 1%. Be proud that you were able to get a nice yield.

When we raise large numbers, such as Wyvern and I, we also go through a lot of casualties, from OE to parasites to accidents and to environmental conditions. I haven't been able to count 100% of my casualties, but I tend to estimate that I get between 85% and 90% healthy yield, which this season will be about 710 releases. That means I lost almost 100 anywhere from egg to 'fly. I had some OE, a couple tac' flies, and a few accidents as well as other unknowns that could be OE, and of course, the eggs that never hatch to begin with.

But when you compare to the wild odds, it's worth the losses that you will encounter so that such a high percentage will indeed make it to fly and grace our gardens with their beautiful orange and black.

[Wyvern]

it's not bad at all. raising in captivity takes a lot of problems off the plate since they are given abundant food and safety from almost all predators. In the wild it's about 1 in 10 that manage to survive to reach adult hood.

[summerluver]

I lost about 60 this year after releasing one healthy monarch from an egg I had brought back to northern NJ from Cape May beginning of July. I had collected another egg which never hatched. Upon returning home I found 7 eggs on my milkweed, which I collected gleefully to raise indoor. Hadn't learned yet that the OE bacteria is spreading like wildfire through the the wild population, and these eggs were probably infected by their sick mom. Other mommies wandered into the garden and laid eggs, which I collected and raised. The OE from the first batch killed all of them and everyone else I had, some as young as first instars, at one day old. I had to wait until the cycle of bacteria finished and read advice on how to kill it from my habitat with a bleach solution, then start anew. Still had a better year than any egg would have fared in the wild, as only 2-3 out of 100 are estimated to make it to the adult stage. You did well! Now I spray my milkweed and even the eggs with a 10% bleach/water solution as I learned, will kill the OE. It's too late for infected cats, and all you can do is isolate them so they don't spread it to everyone else, like in my case.

Dwayne....over 700!! Holy crow. Found only one wild one on my butterfly bush to tag today. Maybe it was one of yours, but I'm still waiting for the motherload!

[Mona Miller]

it's not bad at all. raising in captivity takes a lot of problems off the plate since they are given abundant food and safety from almost all predators. In the wild it's about 1 in 10 that manage to survive to reach adult hood.

I thought it was about 2 for every hundred eggs laid.

http://www.learner.org/jnorth/search/Mo ... es2.html#3
Q. How many eggs the monarchs have in one time?
A. They only lay one egg at a time, but they can lay many in a single day. (The most I've seen is 205 in one day, but this is very unusual.)

Q. What is the most eggs a monarch has ever laid?
A. I have no way of knowing how many eggs wild females lay. However, I have studied fecundity (number of eggs laid) by captive females, and they highest number I've seen was 1179. The average is about 700, but this varies from year to year. They lay fewer in hot, dry summers.

[Jeff Serena]

Thanks to everyone for the information. Another newbie question: Does anyone know what sort of creatures, other than some bacteria, prey on monarch caterpillars in the wild? Thanks again!

[Mona Miller]

http://www.monarchwatch.org/biology/pred1.htm
Predation
Check out the bottom of this webpage, there are more:
At Overwintering Sites : By Invertebrates, Parasitoids & Disease

[David Calhoun]

Not wanting to flog a dead horse, just want a little more detail.I know that cats that I bring in have a better chance, but how about a chrysalis? If you are out in the wild looking for milkweed to feed your cats, and you see a chrysalis , do you bring it in, or figure- Well it made it that far, I'll leaveit alone?
I know that there are a lot of baddies out there that prey on cats, but what preys on or parasitizes a
chrysalis? Thanks in advance. David

[Mona Miller]

I just brought in a 5th instar caterpillar, but totally isolated it:

viewtopic.php?f=27&t=2371&p=11555#p11555
Check this out.

I'd bring in the pupa, but I'd isolate it from the rest of your Monarchs. Once I was watching a pupa that was located on my house, it was nearing the time for it to emerge, something ate it.