Many thanks for the advice. I am truly doing the best I can. I love the butterflies but having this happen is very disheartening. I have planted out a green house with 150 swan plants this year in anticipation of lots of caterpillars on plants outside, so now have 6 foot high plants and minimal caterpillars.. maybe its a late season..
Caterpillars writhing on the bottom of the castle is a classic sign of ingestion of a toxin. This can difficult to pin down as it can come from so many different sources. Disease can still be a possibility despite sterilising, if the caterpillars are carrying it when introduced to the castle, or if the disease is viral rather than bacterial, and “lethargic” is a factor with disease. Sorry I can’t be of more help, but with without seeing the set up, it is difficult to determine.
Thank you Norm.. I appreciate your advice..I do realise that the green showing in photo is the splitting of the skin process and not all were hanging..the otheres were on the bottom of the Castle, stiff and writhing with the green jelly like substance at the anal area. I have 3 caterpillar castles and have in the past steralised with bleach between batches of caterpillars I’ve brought in.. I try not to over crowd. I can not stand to see any creature suffering, so quietly put them in the freezer.. I have a few more caterpillars at the moment and am keeping a good eye on them.. They seem quite lethargic and although I have fresh feed for them.. they just don’t seem interested..I have had dealings with Monarchs for some 15 years at least and this is very odd. I have realeased over 100 so far this season. But I do thank you for your advice..Jill
Hi Jill. I presume the caterpillars in the photo were hanging in their “J” when they died, judging by the cremasters. The green blob behind the head is where the skin has split ready to moult and form the pupa, and once in this position they do not poop, so is this what you are referring to? Or is their poop jelly-like before they hang? The brown colour would possibly indicate disease, which can sometimes be triggered by overcrowding the caterpillars in a confined space, in which case it would be wise to empty the castle and sterilise it with bleach. It is hard to pinpoint the problem as there could be more than one factor involved, but sterilising would be the first step. Please let us know how you get on.
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