Raising Monarch caterpillars / butterflies in Santa Barbara...

Does it make any sense???

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see also:
image gallery of milkweed and Monarch caterpillars & butterflies
Monarch caterpillars eat butternut squash
tachinid flies are killing my monarch caterpillars!
Monarch caterpillars failed to complete pupating into chrysalis... why?

the challenges of growing milkweed for monarch caterpillars in santa barbara

We've been trying to "raise" Monarch caterpillars and butterflies for almost two years. Raising probably isn't the right word, but I couldn't think of a better one. What we've really been doing is attempting to grow milkweed as a food source for the Monarch caterpillars (and the Monarch butterflies can feed on the flowers as well). I discuss how we got started on this backyard project in an earlier post here. Needless to say, growing milkweed here in Santa Barbara (coastal Southern California) and attempting to "raise" Monarch caterpillars has been a challenge. I realize it's not that much of an effort to plant some seeds and water the plants, but once one commits and become emotionally invested, one would like to succeed and an actually see some caterpillars turn into chrysalises and subsequently into Monarch butterflies. We have had some success, but more often than not, we have faced three very real problems: (1) young milkweed plants wiped out, (2) overpopulation/famine, and (3) the dreaded Tachinid fly! These issues have caused me to wonder... is migration critical to Monarch butterfly survival? And does it make sense to grow milkweed in Santa Barbara?

(1) young milkweed plants constantly wiped out
(2) caterpillar overpopulation/famine
(3) the dreaded Tachinid fly!
(4) is migration critical to Monarch butterfly survival?

(1) Young Milkweed Plants Constantly Get Wiped Out:
I have planted a LOT of milkweed seeds. I've used both tropical milkweed (Asclepias curassavica) seed I got at our local hippy nursery/feed store that seemed to be mainly yellow-flowered tropical milkweed, as well as some red-flowered (blood flower) tropical milkweed seed I got from our local "butterfly lady" that I think she "harvested" from her backyard milkweed plants. I've had better luck with the yellow-flowered tropical milkweed, but even so, I've only got ONE large milkweed plant (about 3 feet tall and round). All our other milkweed plants around the backyard and front yard are small and stunted. The problem is that in Santa Barbara, we have Monarch butterflies around all year long (or so it seems), and they are egg-laying machines! The Monarch butterflies come here in late fall to spend the winter in our nearby coastal Eucalyptus groves, and then in the spring almost all of them leave and migrate back up into the Sierra mountains and beyond for the spring, summer, and fall, and then return the following winter. But some of the Monarchs must stay here. I'm pretty sure several people here are growing backyard milkweed, and that at least a few Monarchs lay eggs here in the spring, and the resulting Monarch butterfly offspring stay in this area and keep reproducing throughout the year. In an event, we see Monarch butterflies around throughout the year. The problem is that my small milkweed seedlings never get much of a chance to grow before they get eggs laid on them, and the eggs of course turn into hungry little caterpillars that eat the little plants. The small plants can recover once or twice, but always seem stunted ever after. Somehow I've managed to grow one nice, fairly-large established milkweed plant in the backyard (which has already been completely defoliated twice this year by caterpillars, but has also recovered, at least until the next wave of caterpillars). But all my other scattered milkweed plants are small and stunted (and the butterflies still seem to keep finding them and laying eggs)! I'm not giving up though... my large milkweed plant produced some seed this summer which I was able to collect, and I'm making one more go at starting a half dozen big pots of milkweed.

(2) Caterpillar Overpopulation/Famine:
I've read that a single Monarch butterfly can lay 100 to 300 eggs, and we have multiple Monarchs fluttering around the backyard. I'm guessing that lots of eggs get laid on our single big milkweed plant. In any event, we have repeatedly found dozens of caterpillars at a time on our milkweed. The problem is the caterpillars eat up all the leaves before they are completely grown, and then have no more food. The butterflies are laying too many eggs for the available milkweed! It's heartbreaking to have a bunch of hungry caterpillars and no milkweed. Last year we fed one hungry monarch caterpillar some butternut squash, but that doesn't seem like a very realistic long-term solution. This problem makes me seriously question growing backyard milkweed if the butterflies lay too many eggs and none of the resulting caterpillars have enough food to grow to full size. I'm not sure if growing more milkweed is a solution if it just attracts more butterflies (with each butterfly carrying a 300 egg payload!).

(3) The Dreaded Tachinid Fly!
This spring, our lone large milkweed plant got completely defoliated (again) along with every other small milkweed plant nearby, but we managed to grow at least twenty big Monarch caterpillars before the milkweed was wiped out. We leave the caterpillars alone and they wander off to different spots in the yard and elsewhere to turn into Chrysalises. Sadly, when we excitedly went looking for chrysalises (like going on an Easter egg hunt), all we found were two chrysalises, and at least a dozen dead hanging Monarch caterpillars that had been killed by Tachinid flies. We'd experienced Tachinid fly problems before, but to a lesser degree, and I was hoping it might be seasonal. But now it's looking like it is a year round problem and the vast majority of the caterpillars are getting killed by Tachinid flies. Again, when you get your hopes up to see the beauty of that pale green chrysalis and then the magic of that regal black and orange Monarch butterfly emerging, it's really disappointing and heartbreaking to see a shriveled dead hanging caterpillar. From my research at this point, I have no idea what to do about my new nemesis (the Tachinid fly).

The above problems of the butterflies being able to overwhelm the available local food supply and the problem of the Tachinid fly make me wonder if growing milkweed for the Monarch butterfly IN SANTA BARBARA makes any sense, and it leads me to this question...
(4) Is Migration Critical to Monarch Butterfly Survival?
Maybe growing milkweed here in coastal California where so many butterflies congregate for the winter is fools errand? Maybe the Monarchs migrate as a way to survive, and they aren't intended to stay and live year round in coastal California (Santa Barbara). They come here in the winter to keep from freezing to death. But maybe they then migrate in the spring to disperse and look for a food supply (new milkweed). They then keep moving north and spreading out even more so they are always finding new milkweed plants and are also thinning their numbers so they don't overwhelm the local food supply. Equally important, they spend the summer up in the Sierras (and in Reno where I remember seeing them as a kid) where many of their natural enemies don't exist because it FREEZES every winter. They can fly away to sunny Southern California or Mexico for the winter, but their fellow insect predators (like the Tachinid fly) get frozen each winter and don't exist. So maybe to insure adequate food and safety from predatory insects, Monarchs need to migrate every year to survive.

Although I'm beginning to question if growing milkweed in Santa Barbara makes much sense, I'm not giving up. We will still keep planting and growing milkweed. I recently collected several seed pods full of yellow flower tropical milkweed, and planted a half dozen new pots of milkweed. Much of the milkweed has sprouted, and now all of the pots have many milkweed seedlings in each of them. The challenge will be to keep the butterflies and aphids off of the young plants so they can grow and and get big enough to be transplanted around the yard. If you have any thoughts or personal experience on this please feel free to share them below.

 

Comments / Questions / Feedback:

Comment by Adriana Stuven on Saturday, October 10, 2015
Thank for the information, very good I learn a lot. On Sep 29 2015 I bought a asclepiad in the Las Positas nursery to attract butterfly to my home, I did believe they using to put there eggs on the leaf, now 10/10/15 I found 4 caterpillar in the plant wish is small plant, I read in youtube they need a lot of leaf to grow, I went back to nursery I bought another plant. Now reading you article my question is they will survive the coming cool weather over here? I live in Goleta City 93117. Please help me :Do I making a mistake to grow this carterpilla or I live in the back yard were they are now or to live to their luck or I protected and get more plant to feed the caterpillar inside the home. How big they get, How much they eat I never saw caterpilla before. Thank very much Adriana Stuven

Reply by Steve (Cranial Borborygmus)
Hi Adriana, Thanks for your comment and question. I've never counted, but I think Monarch caterpillars can end up eating between 20 and 30 full size tropical milkweed leaves during their life before they are big enough to turn into a chrysalis. They eat less when they are small, and then eat more and more as they get bigger. Regarding the weather here, I think Monarch caterpillars can grow year round here in Goleta and Santa Barbara, so if there is enough milkweed available, your caterpillars should do fine. But if you get more milkweed, you'll probably find Monarch butterflies have laid more eggs, and you'll end up with even more little hungry caterpillars. Hopefully you've got enough milkweed to get these four caterpillars to full size and they'll be able to turn into chrysalises. Although your milkweed plant(s) will be missing all their leaves, if you keep watering them, they will grow new leaves. It can be tough, but it's amazing to see the caterpillars turn into chrysalises, and then see the Monarch butterflies emerge. Good luck!

 

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