My last two monarch caterpillars disappeared yesterday afternoon. They were the only two still alive and accounted for from the original dozen. They were definitely large enough and ready for their chrysalis stage, so I don't think they met an untimely end like the other ten. They just crawled off somewhere to pupate in privacy, the asclepias incarnata (swamp milkweed) plants they were on were certainly not supportive enough for them.
It's been a very stressful stewardship for me, I was under the assumption that monarchs were immune to predators due to their consumption of the milkweed toxins. That's what all the anecdotal evidence I've read suggested. So when my caterpillars started disappearing one by one, I was quite troubled. Birds aren't supposed to eat them right? I believed I should expect at least 90% of the caterpillars to reach maturity, when in fact I lost 90% somehow. Should I have attempted to protect them? I didn't think I had to, they're supposed to be poisonous. Attempting to protect them might be interfering with the natural cycle of things.
I can't tell you how relieved I was to come across the following information this morning: according to the Monarch Larva Monitoring Project (MLMP), only 5-10% of monarch caterpillars survive to the 5th instar stage, with results being extremely variable. That's real scientific data. My results are normal! Monarch caterpillars do have natural predators, with the tachinid fly perhaps being the worst. I did not know about the MLMP, now I'd like to participate next time a Monarch lays eggs in my yard. They have a ton of useful and informative data over at their website (http://www.mlmp.org/) gathered by researchers and citizen scientists, check it out and consider submitting your observations next time you have monarchs too. It's just that easy to get involved and make a difference!
Elsewhere.....a word of warning.....check your herbs closely before you pick them!
I was making lasagna the other night and went out to my herb garden to pick some parsley and basil. When I reached down to grab a leaf, this little fella moved. It's about 12mm long, some kind of looper or inchworm (moth). I've been checking my parsley for black swallowtails, no luck yet, but this guy's pretty cool too. I haven't been able to identify it yet, according to my guidebooks only black swallowtails use parsley as a host plant. Also the books say loopers and inchworms generally use trees as hosts. If you have any ideas please let me know!