Are you putting them out before their wings are completely dry so they can fly? I never do that because they can't get away from predators. (learned that the hard way.) Some will still get killed, but at least they have a chance if they can fly.

I would also see if you can find any hornet or wasp nests on your house or in the yard and have them removed.

Bald faced hornets will definitely go after butterflies about their own size. Never seen them go after something as big as a swallowtail.

I actually like having an active bald faced hornet nest nearby (would not want it in my yard) because they keep the yellow jacket population down. A number of years ago, neighbor two doors down had a big nest in his tree. My family got to eat outside in August and September with zero yellow jackets hassling us. Was wonderful.

Just had an idea and confirmed it. European hornet would be a possibility. I just read they will go after large Leps.

European hornets are pretty laid back except when it comes to protecting their nest. In 2002, I got to watch a bunch of them deconstruct my lilac bush. I was able to stand amongst them with no worries. Unfortunately I had no video/camera equipment there since I was in the process of moving.

That is why I switched to hummingbird plants in my yard. After watching a giant fly/wasp/bee thing carrying off one of my BST cats, and seeing about 20 cats on my bronze fennel disappear. I have put some milkweed back in and bring the cats indoors to raise.

We wait a couple hours after butterflies eclose to put them outside. We never had any incidences like this before with them being attacked. It really is looking like any butterfly that is or will be hanging around here will be doomed because of these vicious savages. I know it's nature, but I will favor a butterfly over a hornet. My daughter saw a hornet flying around the butterfly bushes today and it was obvious that it was looking for butterflies to kill. There's been one Monarch hanging around here yet, but she said the hornet was picking on it earlier and she just went outside awhile ago and there it was on the ground dead.

KC, It's funny that you mentioned a lilac bush because other years I noticed these huge things (I think they're the same thing as what we have here now) hanging around our one lilac bush. I don't know what they were doing because after seeing their size I didn't stick around long enough to find out. I looked up both the European hornet and the bald faced hornet, and it must be the European hornet because of the yellow. We never had problems with yellow jackets like we're having with these hornets. They haven't gone after us but the fact that they're attacking all the butterflies that they can makes them unwanted here. I don't know where the nest is, and I don't know what to do about this problem. It makes me want to kill all of them if they don't sting the heck out of me first. They look vicious to us, and butterflies are obviously very much on their menu, which infuriates me.

mblan, It's good that you're bringing the cats in to raise so they stand half a chance. If I'd let them outside for nature to take care of, I can almost guarantee that something would kill them. I've seen them being killed by spiders, assassin bugs, robber flies and some other things that I didn't know what they were.

Cathy

I've killed 3 so far, and yes they have been going after my butterflies. There's two more out there. I don't know where they are coming from because I don't see a nest. I shoed away a European Hornet. He or she didn't like that. Creepy looking things even for something so docile. Between those and Cicada Killers, they give me the creeps. I think the hornets are getting smarter or intimidated by me lol.

gfos, Sorry to hear that they're going after the butterflies at your place too. That's what we'll be doing, trying to kill them when we see them if the trap that we got doesn't get them first. My daughter and I just got back from Walmart where we went specifically to get a trap for hornets, yellow jackets, and wasps. So she said she'd read the directions and put it up tomorrow (actually today now since it's the wee hours of the morning). It's supposed to rain here, so it might get put up or it might wait until Friday. I don't think it's supposed to rain all day, so she'll probably get it hung today (Thursday). I saw one online that has a solar-powered blue light included with the trap that attracts them. I have been reading up on European hornets and saw that they are attracted to lights, so it sounds like that trap would be nice to get too. I know that there's a gel bait that comes in a tube/cartridge that is supposed to be put on the tree/bush that the hornets are girdling and that they would carry it back to the nest and it would kill other hornets in the nest supposedly within the next few days or so. I'm just not sure if it would kill anything else that might land on the stuff though and so I'm reluctant to buy that. I also saw another gadget with a light to attract them and then something that spins around chops up the hornets, but the trouble is that the website also claimed that it would also kill "moths and other pests". If they consider moths a pest, I wouldn't buy anything from them even if it would kill the hornets. I don't want to be killing moths.

My daughter also got a nice fly swatter, but I said as huge as those hornets are and mean-looking, I think I'd feel intimidated standing outside with that thing trying to swat at them. I hope she doesn't get stung if she actually intends to do that. She did manage to knock one to the ground with wasp & hornet spray last evening and had me stomp on it because I had shoes on instead of sandals like she did. If she was afraid it would sting her through her sandal, I don't know why she can't picture them coming after her when she's batting at them with the fly swatter! Well, I really hope that we can reduce their numbers. It's the first time I've ever wished that we didn't have butterflies here. I want them to move along so these hornets don't kill them. They seem to mostly go after the swallowtails and the monarchs and don't really bother with the loads of Silver Spotted Skippers that we have here. I don't know why they seem so determined to kill the prettiest ones.

I wasn't sure what a cicada killer looked like. I don't know if we have those here or not. If we do, I haven't noticed them. I hope that cicadas are the only things that cicada killers kill and not butterflies. We have enough trouble here already with these darn hornets.

I don't release the moths I raise at my house. I drive them at least 8 miles away. You could release your butterflies elsewhere too.

You know, KC, that's not a bad idea! I really hadn't thought of that. Under the circumstances, I think that it's a good possibility that we will do that. I really don't want to see more butterflies killed by these hornets. They really are vicious and I don't understand why they do it because as far as I know they don't even use them for food here for them or young ones. It's kind of like house sparrows killing our native birds; they seem to do it just because they can. Anyway, thanks for the suggestion! Do you drive your moths away from your house to avoid predation of them at your place?

I do it to avoid inbreeding. Nature has ways to avoid it but I'm raising more moths than would naturally be found in a square mile so I need to make sure I'm not screwing up nature.

And it is at least 8 miles because experiments have shown cecropias can find a female from up to 8 miles away. I do mark some of my males and so far, none have made their way back to their sisters/cousins.

I don't do it with butterflies because: (1) I don't breed them and (2) pheromones are not key to them finding mates.

That's interesting to know. I hope that here at our place we're not screwing up nature and contributing to inbreeding of butterflies if that's not good for them. I remember one year when we released a bunch of pipevine swallowtails one day and later when I went outside there were at least half a dozen pairs hanging from the coneflowers in the garden mating. I doubt if 12 of the ones that we released found "foreign" mates that quickly. As long as I've been raising butterflies, I still don't know for sure if inbreeding would cause dire consequences for them. I might be helping their population but harming the gene pool.

I just released my last monarch today and it landed on my butterfly bush, 3 minutes later one of those hornets attacked the monarchs underbelly

I’ve released numerous monarchs and never had this happen

Michel, I guess you must know then how upset I am when I noticed Monarch body parts outside that have been killed by the European hornets. If I'd ever be able to find the nest and it would be low enough, I'd surely make the best attempt I can at eradicating them. We live beside a woods and I can only imagine that their nest is up high in one of those trees. I've never attempted to follow the hornets because there are so many rocks on the ground in there that I'm afraid I might fall while in pursuit. I also don't know how someone else would feel about my walking on their land. That sounds like you have figured out a good way to locate the nest. Hopefully, I'll be able to eventually. For the time being until they're not around anymore this year, I have to settle for using a foaming wasp and hornet spray that knocks them down and thank goodness I haven't gotten stung yet. Almost every time I venture up to the one lilac bush that they've been girdling the most for some years already, I can usually find some there working on trying to destroy the lilac bush. They seem to be doing a good job of that because our lilac bushes are looking pretty bad from one year to another with this year being so much worse than last year. I'm tempted to just cut them down and let them start over from scratch, but I know that that won't keep the hornet away. As a matter of fact, it might encourage them even more having that tender new growth at various places. I just don't know what to do to keep them off of our lilac bushes. I can't spend all my time out there holding the the spray can all day and constantly walking from one bush to another. We've tried using traps that are meant for them by mixing the attractant with water and putting it in the trap. We've caught very few that way. I wish that some company would come out with a better idea.

I see that I wrote four years ago that I liked having bald face hornet nests nearby but did not want one in my yard. Well, this year it was my turn to have the nest in my yard. Nest was about 15' high in one of my pine trees. I walked right past the tree multiple times a day and mowed underneath it. Got zapped just one time. Was in a hurry while going past tree and sentry must have decided I was a threat. Something hit me on top of my head and then the pain started. Lasted a few hours. First time a bald face hornet has gotten me.

Gosh, you'd think that with that hornet nest being about 15' up in the air that they really wouldn't have bothered attacking you. It seems like that's enough space that they wouldn't feel frightened, but then again, what do I know, I'm not a hornet.

Pretty many years ago, I also got zapped by a bald face hornet when I was outside picking raspberries The nest was hanging really close to where I thought they'd be. I was stung plenty of times over the years by yellow jackets, wasps, hornets and maybe even a honey bee one time if I remember correctly. I think that was the time when I was clapping at our dog (many years ago, as I was a kid) and wouldn't you know it, that was just the time when one decided to fly in my bubble and I got zapped. I think the two times when stings hurt the most, though, was when I was zapped by the raspberry patch-living hornet and also two different times when I inadvertently reached right onto a saddleback cat. Ouch, I was surprised that a caterpillar sting could hurt so much.

I really intend to use your "tennis racket" zapper method starting next year to "try" to annihilate those doggone European hornet butterfly murderers. Maybe I can also get the population down from a million to half a million like you did. Hey, it's a start anyway. I certainly can understand your saying that because there are sooo many of the potato leafhoppers. I think I remember reading about some bait that a person can put on the lilacs that they're stripping the bark off of and they carry it back to the nest and it also poisons the other hornets, so that's something else I can try. I have to look into exactly what to get. The way I look at it is that they don't belong here, so I don't feel the least bit guilty killing them. It infuriates me when I see them patrolling the butterfly bushes looking for their next victim. I feel better this year than last year and will be taking a much more proactive approach next year to eliminate the invasives, whether it be insect, bird or plant.

My understanding is that bald faced hornets are pretty mean. We had a nest in a bush a couple years ago, and I mentioned it to a guy working on the foundation (mice exclusion - it's a fieldstone foundation), and he took one look and informed me that it was a bald faced hornet nest and that they are the type to not only defend their territory but chase beyond it ... he asked if he could spray it (which we were happy to let him do) then emptied a can of wasp spray into it ... conveniently the opening aimed out, and it did them in.

BBB, I'll have to do more reading up on the Bald Faced Hornet, as I don't know a whole lot about them. After reading the Penn State Extension page on them, I learned some things including this:

Baldfaced hornets can be considered a beneficial insect in that they reduce populations of unwanted insects (including other yellowjackets) and will help pollinate flowers when they are searching for nectar. Therefore, unless the nests are located close (within 10 feet) of an entrance to a building, under an eave that is close to the ground or in shrubbery next to a lawn that is mowed, the nests can be ignored. However, individuals with known sensitivities to wasp and bee stings should have any nests close to their homes removed by professional pest management personnel (pest control companies).

So it sounds like they discourage people from killing them; however if those hornets were close to where you were having work done, well, what does a person do in that case?! I try not to upset the balance of nature, but then again, I do make exceptions. I bring in Black Swallowtails to raise and once in a while a wasp comes out of the pupa instead of a butterfly. Here again, I'm not extremely knowledgeable about wasps, but if those creatures are native, maybe I should get thirty lashes with a wet noodle because I kill them. I figure that I see a lot more wasps than I do butterflies, so I will pretty much always take the butterfly's side rather than the wasp's or other creature that kills the butterflies.

The bush is about 15 feet from the front door and the basement door, but the strip of lawn that runs along that side of the house is pretty narrow, so yes, we walked within a foot or two of the nest when going down that side of the house, and the worker would have been pretty much on top of it and likely would have bumped the bush. It was a sting waiting to happen where it was. Other than that, the places wasps aren't allowed? Living between the window and the screen (their nests will get knocked down until they leave), under the shingles near the faucets (those got tracking powder puffed in), in the charcoal grill that hadn't been used for a while (I believe that was another case of just getting rid of the nest ... and running, with the grill), oh, and in the under eaves space when we opened up a wall ... that thing was enormous (like beachball size with a volleyball sized add-on) - it got tracking powder and who knows what else).