August 28, 2023 at 12:10 PM - Posts: Determine caterpillar death cause, Title: Breeding Butterflies: Experiences, Questions and Answers
Hello everyone. Once again i come here with a question, or maybe more of a request for some help and insight. I am trying to understand a bit better the causes of death of the caterpillars by the way they die...
I bet anyone who has bred any species of butterfly or moth must have had a few deaths (or more, sadly). At least i never managed to raise any with 100% success rate. That being said, I have seen caterpillars of the same species and in the same container die in various different ways.
1) Some just shrink and turn tough to the touch without any change in their original color (i believe that would be caused by dehydration), which for instance happened to some A. lorquinii and A. atlas i am rearing.
2) Some die with the typical NPV, climbing to the highest spot on the branches and turning a brown soft "pudding" hanging from the branches ( i believe it happened to me on my first monarch caterpillars)
3) Some shrink and turn brown and soft but with no signs of vomit. Fungal infection maybe???
4) Some just stay the same size and color as normal but vomit themselves to their deaths. I would place that on the bacterial infection/bacterial toxins section. Bacillus thuringiensis would cause that as the toxins it produces on the leaves' surface dissolve the caterpillars gut.
5) Some die with diarrhea. Bacterial? Fungal?
6) Some die with black dots under the skin and diarrhea. Happened to the only 2 Actias sinensis caterpillars i had a while ago. Possible fungal infection?
7) Some die trying to shed their skin. Usually happened to the ones with spikes like automeris or leucanella. I believe that would be too dry of an environment and as a result their skin gets stuck.
Saved the most annoying and frustrating and infuriating to me at least. The ones who die out of the blue and with no apparent cause, just teisting around non-stop for 1 hour or so. Lika a child spinning till they fall to the ground dizzy. I have had that with Leucanella viridescens and i believe it was an intoxication as out of stupidity i fed the larvae wisteria. I saw someone's comment here on Actias that they fed this host plant and the larvae ate it... probably just forgot to let everyone know that the foodplant ended up killing all their larvae as it is for a fact toxic to Leucanella. However now i am breeding a bunch of Bunaea alcinoe caterpillars from 2 matings. The larvae hatched well, loved drinking water right after they hatched (it is actually quite fun to watch this species drink) and soon started eating the 3 foodplants i offered them, Ligustrum, Robinia and Liquidambar. They soon all went to Liquidambar so i removed the other leaves. Now some caterpillars of the first pairing are shedding their skin and some before and some after they have shed just fall to the ground twisting around......today one which had already shed the skin and looked perfectly healthy started doing that right in front of me and it was the first time i witnessed the beginning of it. The caterpillar was walking on the side of the plastic container like it was nothing, then in a matter of 1 or 2 seconds it just started the twisting disease (that's what i am calling this...). After some 15 mins of this dance i just took it out and put a drop of water on it. I knew it was going to die so i just did that out of curiosity to see if something happened. Well... the caterpillar stopped the spinning and started walking normally again, although very slowly as it might not have much energy left. In 2 or 3 minutes is started the twisting once again, which lasted for like 30 minutes until it died... i must say this is quite annoying and the worst part is not being able to point out any cause for this madness. Out of the 43 caterpillars i kept from my first pairing some 7 or 8 must have died this way. I really can't find anything on the internet or on some books i have. Pesticides aren't used on the zone i collect my Liquidambar from. These caterpillars vomit themselves with any tiny touch and still the ones dancing around don't throw anything up. No diarrheas. Definitely no color or size changes. Just twisting and turning until they run out of energy. If anyone has any clue what this could be please let me know.
Also if anyone wants to add something to the 7 previous points or correct something please leave on the comments. If you have experienced other patters of caterpillar death appart from the ones stated above please feel free to add them.