Problems with Monarch cats

7 years ago

I have tropical milkweed planting in the garden and have been finding hundreds of eggs and cats (the ones I miss as eggs) and bringing them inside over at least the past month. Then my daughter feeds them and cleans the containers that we put them in. We had great luck with them at first, but now for about the past week we've had a lot of them die. We either find them hanging limp or lying in the bottom of the containers dead. Sometimes there is a mess of black goop under them. It's very discouraging!

At first I thought it was some kind of a disease, but now my daughter mentioned to me seeing some kind of small insect flying out of some of the containers. I haven't seen them so can't really describe them other to say what she's told me, that they fly out when she opens the lid and they're two or three times bigger than a fruit fly. I'm assuming that they're small enough to be able to fit through the screen that I have put on part of the lids of the containers. I'm assuming that something flew in there and laid their eggs in the cats just like the tachinid flies would sometimes when we'd find a caterpillar outside after a tachinid fly has already gotten to it. So I'm kind of assuming that these "flies" are the offspring of whatever insect got in there in the first place. I haven't seen any pupae of any kind unless they're so darn small they're almost microscopic or they blend in with the cat frass.

My daughter has been disinfecting the containers with Lysol wipes if that helps get rid of any diseases that might be going around. I was hoping that since we have them in so many shoebox-sized containers instead of one or two huge storage containers that that would help prevent the spread of disease if the problem is something that can be passed around, but they keep dying. It isn't just happening in one container but in all 20 or so containers

We've released hundreds of Monarchs this year and I had said to my daughter soon after the Monarchs started showing up here this year that the way it was going she might just pass her record of 650 or so last year, but now with all of these casualties I'm having my doubts.

We were just at Walmart and bought some of the same shoebox plastic storage containers with the lids, only now we're going to leave them as they are instead of cutting a big long hole in the top and putting screen in its place. That way if something has been flying in the containers, I'd think that should put an end to that. I just don't like the fact that then there will be a lot of condensation in the containers with no air flow, and I'm not sure how much oxygen the cats need each day. I've been doing this since 2005 and have never felt so baffled with what's wrong and what is the solution.

Has anyone else had this happen? I'm at a loss what to think

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Comments (5)

mblan13
7 years ago
Probably Tachinid Flies.
caterwallin
Original Author
7 years ago
Thanks for the reply but no, I know it's not tachinid flies. Whenever we have a caterpillar that's been attacked by a tachinid fly, a string hangs down from the caterpillar or pupa, the fly larva crawls down the string, goes under the paper towel in the bottom of the container, and then within a short time we find the reddish-brown tachinid fly pupa in the bottom of the container under the paper towel. I've been raising Monarchs for 14 seasons and this is the first time I've had this problem, whatever it is. I wasn't really expecting a solution from anyone but was wondering if someone on here ever had this problem with the Monarchs before, that little "flies" would fly out of the container and there'd be dead cats inside the container.

I originally thought that this was some kind of a disease being passed around from one cat to another, but then when my daughter said she saw some kind of insects fly out of the containers, that made me suspicious that they were the cause of this huge die-off. It's very disturbing. Even though I don't like the containers not having air flow, the only thing I can think of doing besides disinfecting the containers is putting the solid lids on the tops of the containers instead of having screen for bugs to possibly get inside, even though I never knew before that that's possible.
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Iris S (SC, Zone 7b)
7 years ago
Wish I could be of help. Hope you will figure it out and share. Not long ago I had some little black somethings identified here. The first answer was caterpillar fras, but it turned out pupa of wasps that go after caterpillars. They were really just weird looking things on a leaf that caught my eye. Seems there are so many things that can go wrong with caterpillars. Good luck! Here is a picture of the little specks. Doesn’t look like anything really, does it?
caterwallin
Original Author
7 years ago
Gosh, there's a bunch of of them there, isn't there! I've never seen anything like that here. How did you know that they were wasp pupae? Did you see any come of them? Yes, there are so many things that get after Monarchs that supposedly only one or two out of a hundred hatched make it. I've seen people on here mention it various times, but I really don't know where the original data came from. It's why so many of us raise them in containers, to help their numbers. It's a ton of work for my daughter and me and we get little else done, but I guess we feel obligated to help the Monarchs since their numbers have decreased drastically over the years.
Iris S (SC, Zone 7b)
7 years ago
last modified: 7 years ago
You are doing a great job! Sorry for the late reply. Someone on the insect forum knew what they were. The pictures I compared them to on the Internet matched. I walked by there today and took a picture. There are two that looked like flies. But maybe the one on the lower right is just coming out? It’s really hard to tell. They are maybe around 3 to 4 mm.