As usual, I'll give you the good news first. Another chrysalis formed early this morning, and 3 more caterpillars are ready to pupate. In addition, 3 more are almosted finished eating and will be ready to pupate within the next 24 hours.
Next, the bad news. A couple of days ago, one of our caterpillars made its chrysalis on one of our Milkweed flower pots. Yesterday, I noticed that one spot on it was turning a slight brownish color. I thought maybe it had gotten injured or something but would be ok. However, this morning, it is clearly dead. (see photo below)
(Silky string from chrysalis to the ground / Tachinid fly larvae kill a Monarch chrysalis)
The Tachinid fly lays eggs on the caterpillar. The fly larvae eventually kill the Monarch caterpillar around the time it tries to pupate. Or, sometimes they wait until the caterpillar has become a chrysalis, as shown in the above photo. The silky string connected from the chrysalis to the ground is the tell tale sign that the Tachinid fly has struck.
This is probably the 6th or 7th caterpillar of mine that has died due to this parasitic fly. At the nursery where I'm currently getting my Milkweed plants, the plants are out in the open, and the flies can openly get to the developing caterpillars there. So, my wife suggested that in the future when we buy more plants, that we remove all caterpillars and put them on other plants. However, any eggs we could leave, and these would not have been infected with the fly larvae yet. I think it's a marvelous idea. This will help us to get the most out of our Milkweed leaves too. You just hate to invest all of that Milkweed and then get nothing out of it.
I don't mean to say that the Tachinid Fly is all bad. It preys on other garden pests such as Japanese Beetles, Squash Bugs, Stink Bugs and more. However, since it preys on my beautiful Monarch caterpillars, it is a neusance to me. Hopefully, keeping my babies in an enclosure will do the most help.
One note: Please be careful not to use any poisons or pesticides to get rid of pests such as these flies because it will kill your butterflies too. The Milkweed sap they consume is poisonous, and therefore, the Monarch is full of poison already. It's body just can't tolerate any more. So, look for natural ways to control pests and predators.
Perhaps these observations will help you too. Be sure to keep your caterpillars in a protective enclosure at all times. In my next Blog entry, I'll show you a pavilion that I have that has worked great for me.
Happy Monarching!
Caleb & Janae Warren
I have tons of those flies this year, and we have had the same problem with our monarchs. We have "raised" monarchs for years, and this is the first. We lost 9 out of 11 in the first batch, 2 chrysalis; 3 out of 6 in the next batch. Wondering if I need to "spray with chemicals" in order to stop the flies from coming and save the plant for next year. Any suggestions from anyone?
ReplyDeleteThe much maligned and misunderstood tachinid fly strikes again. First, Lespesia archippivora, the one that feeds on monarch butterflies, is only one species in a family of thousands (1300 species in our area). They parasitize a huge variety of species, many of them pests, such as stink bugs, tent caterpillars, earworms, and many others. In fact they are used as biological controls. The one that feeds on monarchs is also a biological control of armyworms. So, paradoxically, it helps monarchs by allowing to reduce pesticide use. I empathize with your feelings if the ones you are lovingly raising fall victims to this parasitoid. It won't do any good to kill them, though. No chemicals, please. http://bugguide.net/node/view/264987
ReplyDeleteThis comment has been removed by the author.
ReplyDeleteI have only been able to have 2 Monarchs this year out of 140 caterpillars total, due to this fly. I hung a fly trap but there must be a way to eradicate it from my yard without poisoning my milkweed. Please give us suggestions.
ReplyDeleteKim I dont think there is any way to stop them. When I put a sticky glue near the milkweed, i accidently caught and killed a monarch butterfly. so no more than that. The only solution is to go out and find monarch eggs on the plant and remove and incubate them inside before the flies can get to them. I now have around 16 healthy chrysalises and the first butterfly born this season since i discovered the issue. When I find a caterpillar outside, i move it into a small cage I have as a "hospital" to feed and see what happens. Ive lost count at thsi point but I will say there has not been a single survivor yet. Once the poor caterpillars dies, I flush it. Its impossible to control the flies successfully reproducing out there but at least I am stopping the ones I find to help a little.
Deletethis is the first one who has made it since i started collecting eggs. a very happy success! https://photos.app.goo.gl/ShPhHGm9WwKBXxA23
DeleteI agree with everything you said. I've released about 300 but my freezer shelf has about 100 frozen bodies. I have no problem squishing aphids but I don't want to see green hemolyph. I wish Rescue Fly trap made a T Fly lure bait. I called them about it and they talked to me like I'm insane. 😛
ReplyDeleteglad you saw my reply! i found this page when i (yet again) google searched how to get rid of these flies. i see nothing being offered, its really frustrating. thats so awesome you have released that many! i find flushing works best for me to not see the grossness either - dont really like the idea of them dead in my freezer with my food. my mom used to get this yellow fly poison and kept it on the kitchen counter - it was so gross seeing their carcuses. i wonder if they arent attracted to it like common flies?
DeleteI am exploring how the evil fly came to be so prevalent and bent upon assassinating Monarchs. There are many species and at least one was irresponsibly introduced to attack Gypsy moth caterpillars. I have noticed a number of Monarch caterpillars with only one (albeit fatal) maggot and wonder if there is pesticide OR immunization at work in keeping the numbers down. I've read that some type of fly uses a virus to avoid immune system attacks on maggots and, one way or another, I have hope that an immune response can be bolstered in Monarchs to beat the wars against Tachinid flies, OE, and the tiny wasp that some folks find attacking pupae.
ReplyDeleteDoes anyone know how to check my newly hatched Catterpillars before I go through the long ordeal and have to kill them when I find out they have been infested with T-Fly.
ReplyDelete