Rather than write a new post for 2011, I decided to add an update for the summer of 2011. I am adding some new information in the yellow boxes immediately after this post.
Many Bitterroot Valley residents may have noticed the thousands of white butterflies flitting about our pine forests in the last week. The pine white butterfly eats the nectar of flowers including rabbitbrush and beebalm. The pine white butterfly is usually found fluttering up high among the conifer trees. Males patrol near host trees for females. Eggs are laid stuck together in a row on a conifer needle.
Some people consider the pine white a forest pest because the caterpillars can sometimes defoliate conifer trees. The caterpillar eats the needles of various conifers including pines, Douglas-fir and true firs. Rarely, they can outbreak and resemble a summer snow storm, though, this has been very rarely witnessed. This summer is the most I have seen of the Pine White Butterfly in my 10 years in Montana.
The range of the Pine White Butterfly is British Columbia east to Alberta, south through Rocky Mountain states and California to Mexico; range just extends into western South Dakota and western Nebraska. There is quite a bit of local variation in color, pattern and even wing shape.
I noticed the larvae stage of the pine white butterflies much more this summer. The larvae looks like a green inch worm. There were literally thousands on my property. When they get ready to mature into a butterfly they stick in one location and you can begin to see the wings form and color change.
It was about 4-5 days ago when I first began to notice the butterflies. Now, the butterflies are seemingly everywhere. It is quite an amazing sight watching thousands of white butterflies flitting about the Ponderosa Pines. I can still find a few larvae stage worms but most seem to have morphed into their adult stage.
In my estimate there are considerably more butterflies this year than last. So, unless we have a weather pattern that significantly harms the pine white butterflies from now until next August, I would anticipate another very large outbreak next summer.
Tree Damage
The pines on my property are very mature but there is still noticeable damage. None of my trees appear to have enough damage to kill them, though. Smaller pines may not fair as well. I do have some younger Douglas Fir but they appear unaffected. Douglas Fir are not immune to pine white butterflies, though, Douglas Fir don’t fall victim to the butterflies until you get west of Montana. I can envision widespread destruction of trees possible if there were a prolonged outbreak lasting several years. I am trying to contact an expert on these insects. Hopefully, I can contact Brytten Steed again this year. I will post a new audio podcast once I am able to reach her.
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{ 50 comments… read them below or add one }
Thank you for this great info! Are there predators on the white pine butterfly? If so what and whree are they??
ellen knight
Thanks for stopping by Ellen!
Happy you found the information useful. Evidently, chipmunks and ground squirrels will eat the larvae. Various birds eat the butterflies and larvae as well.
BB – do you know of any toxicity associated with ingesting the butterflies? I had a dog get deathly ill after a hike on Sunday where she ate TONS of butterflies. Our vet isn’t sure what caused her illness other than her liver was very unhappy. We have tests for other diseases pending but I can’t help wonder if the butterflies may have been the culprit. Any Lepidopterists out there???!!
They have “mustard oil glycosides”. Whether that chemical is toxic to dogs, I can’t say. Who is your Vet? My wife works at Willow Mountain Vet. I will have her ask the doctor tomorrow. Let your vet know about the mustard oil glycosides and maybe they can find information about canine reactions to the chemical.
Sorry I couldn’t be more help. If my wife finds out something relevent I will post tomorrow.
Natasha
Evidently this compound is toxic if ingested in large quantities. And it is found in the Pine White Butterfly.
“Brassicaceae – Injestion of large amounts can be fatal due to mustard oils.”
How is your dog doing? Hope she is getting better!
Thank you for identifying what I have been watching all day. I have thousands of white butterflys happily playing around my house. I live on the border of Oregon and Idaho and look forward to watching these butterflys flutter around. 8/19/10
I’m happy you found the post useful. Keep coming back!
Where do these millions of butterflies SLEEP?! We have them here in the mountains in Cascade, Idaho!
Good question. Do they SLEEP? There is a report of them being so numerous in British Columbia one summer that it looked like snow on the ground when they died. This summer is the most I have seen in Montana.
It’s the most I have seen here in Cascade too. I have seen them on the drive up in previous years along the river but never so many on my property!
It’s beautiful. I do hope they’re not a threat to our trees.
Any more info on that?
Thanks!!
The person I spoke with wasn’t concerned about severe damage to the pine trees. Nothing like what happens if the pine beetles come through an area. They pretty much kill everything in their path.
I think I will do a follow up to this post. I was thinking about an audio (podcast) interview with a Forest Service biologist familiar with these butterflies. If you have specific questions, I would be happy to ask them. I will ask about the damage potential to the trees. I am also curious as to why there are so many this summer.
Hi!
Watched early this morning b4 the sun came up and the butterflies cling to their pine needles! When the sun came out and you could tell they were warming up they started their “dance.” Perhaps they cling all night and when they warm up fly?
Questions I would have are: We have Ponderosa Pine, Douglas Fir and Tamarack. They like all of these! We have also planted Quaking Aspen and they don’t care about those at all. So… are any of my trees in danger?
On a morning walk we saw quite a few dead ones so wondering if their life span is coming to and end here in Idaho OR: What is their life span?
I too am curious about why so many? We have had our home here in the mountains for 12 plus years and this is the first year I’ve seen butterflies like this! What conditions made 2010 so desirable?
Thanks!
Kellie
Just got back from a hike up Bass Creek and had to know about all the white butterflies. Thanks for the information. I found a lot of sites for Montana butterflies – They all seem to list the scientific names and then you can click on them to see a photo. That seems totally backwards to me and really not helpful at all. Your site had great info. and easy to find, thanks!
Dave,
Glad you found this useful. Keep coming back.
omg! thanks for the info we went to gird lookout this weekend and they where EVERYWHERE it was like a snow storm!! my coworkers didn’t believe me now i can prove it! If you get the chance to drive over Skalkaho pass you will definately see them. sooooo incredible
This morning I awoke (08/23/10) to a beautiful site of butterflies fitting about like snow in the summer. I was amazed and then worried…. Thank you for the info. We live in Eastern Oregon and the forest is full of these beautiful critters – well, until about 30 minutes ago, when they seem to have almost disappeared. We have lived her almost 10 yrs and have (als0) never seen anything like it! It is amazing how something so special could possible hurt the forest, but we have learned so much living here (crummy ol’ pine beetles). Please let us know if there is something we should do to help the Ponderosa Pines.
evilkttn,
Glad you can prove your coworkers wrong. Hope you keep coming back.
S&S,
I am climbing Trapper Peak tomorrow. I have a call set up with a biologist on Wednesday. I should have some more information then. Hopefully, the biologist will agree to an audio interview. If not, I will write a post about our conversation
Hey there Bitteroot Bob,
The beginning of last week I noticed white Butterflies all around our neighborhood, but only orbiting the Pine trees in the common area, park and other lots. I am a bit of a nature buff myself, so I decided to take a looksie. I memorized the markings and headed straight for my PC and the Internet. I hope the litte Pine White Caterpillars do not damage all our Pine trees, they create good shade for my home office when the Sun is setting. I found the adults feeding on yellow flowers below and to the side of the Pine trees, only to be taken by very cleverly disguised Ambush Bugs, but the majority are happily flitting about chasing the ladies.
Karl,
Happy you stopped by and hope you keep coming back. I will have some more information on potential damage and such soon.
Bob
I live in tri cities Washinton,moved up fron central OR.I have just in the past few days been noticing these small white butterflies in the pine trees here at my apt.complex, was courious about them and dont recall seeing them in OR.Thanks for all the info!
Lori,
They are all through the Northwest. People don’t pay much attention most years, as there are very few of them. They are in Oregon, though.
Thanks for coming by, hope you keep coming back.
There is an alert coming out of Boise, Idaho on these butterflies, today. That is the delay in getting the Podcast completed. I have spoken to several entomologists here in Montana. I have been assured an audio interview to get everyone’s questions asked and answered will happen. Keep checking back and I will have some updated information on this matter from a true professional.
Thanks for your patience!
BitterrootBob
The Pine whites are in Boise this morning. I saw them at Sagehen Reservoir this past weekend.
Ken;
Evidently, Idaho has a worse outbreak than Montana and other areas this summer. That is why we are waiting on the alert coming out of Idaho.
I am getting on a podcast with an entomologist in a few minutes. I will get the audio podcast posted ASAP.
Thanks for stopping in. Keep coming back!
I have a tree service. Will they be able to spray for the butterflies? My Austrian pines (Caldwell, Idaho) are aflutter with the b’s. and I can’t believe that is healthy. What to do?
I do not think the Caterpillars will destroy the Pines, due to the fact they are not like the ecolgical pest known as the Pine Beetle, which bores tunnels through the trees and stops water flow, wich the trees need so desperately. The Caterpillars will only eat the Pine needles.
We first noticed them this past weekend in Spokane. Have lived here 35 years and never noticed them before. It wasn’t a snow storm but probably a dozen or so. I first noticed them on my “Butterfly” yellow marguerite daisies.
Yes, many here too east of Corvallis, MT in the Bitterroot Valley. I’d like to know more about caterpillar predation by birds, squirrels, and maybe chipmonks of which are numerous on my acreage. Butterfly density was much less than a “snow” but numerous enough to have me concerned – I’d hate to lose my pine trees – especially if a treatment is warranted in my case. Any comments?
Mary
kgoesele
Lee
Bruce
All your questions I believe are answered at the following link:
Pine White Butterfly Update
I did this update with an entomologist out of Missoula. If you can’t listen to the podcast on your computer, you can download to an MP3 player or your cell phone.
The butterflies aren’t as damaging as pine beetles but they can cause severe damage. One of the determining factors will be the egg survival over the winter. This is the worst outbreak since the 1970s. Idaho has a much worse outbreak than Montana, although there are quite a few in the Bitterroot.
There is a spray for them that won’t harm beneficial insects. Brytten covers that in the podcast.
Thanks to everyone for stopping by and keep coming back!
I listened to the Podcast before you entered this link. I found it on your website Bitterroot Bob. To say the least, it was informative and I learned more about the Pine White. Activity here in Star, ID has decreased, but you see a few stragglers here and there.
I didn’t know much about these beautiful little butterflies until yesterday (still need to know more). They were all over the place in our back yard. It was quite a show! I temporarily caught one to look it up and found several websights on them. We have quite a few trees around this area but not much for pine trees. They didn’t show up in my neighbors’ yards so I’m curious as to what would draw them to ours. For a few hours is was almost like fall and white leaves were letting go of the trees and floating to the ground. It was wonderful. I’ve never seen anything like it!!
Audra,
If you look at the top of this website and to the right of the page you will see the Header, “HOT OFF THE PRESS”. Look at the second link down under it and that is the Podcast on the interview Bitterroot Bob had with the entomologist. The interview is informative and I am sure you can learn quite a bit about the Pine White.
I was just wondering if anybody else has millions (and I mean millions!) of those green caterpillars in their pine trees????? Their poop is everywhere and our pine trees are all full of webs! It is so disgusting!!!!! I have lived in our house for 34 years and I have never seen this! DNRC said the last bad outbreak was in the 70′s but I can’t remember the White Butterflies being as bad as last summer. I can only imagine how many Butterflies there will be this year or maybe all of our pine trees will die. The caterpillars have eaten alot of needles and our trees do not look very healthy.
Wendy Dutton
We have the larvae everywhere. Much more than last year. I expect many more pine white butterflies than last year. I am starting to see the first butterflies in the last couple of days.
We had a major swarm for two weeks of the Pine Whites before last Winter, but have yet to see any Caterpillars activity on our Pine trees and the temperature has been ranging from 70-99 these past few months. Our Pine trees look healthier then they have ever been…knock on wood! No pun intended. I will keep my eyes open, since I have Pine trees right behind the house and I work from home. I have windows on each side of me.
Karl, where do you live? I can’t believe you don’t have caterpillars! I live on the westside of Hamilton, off of Owening Lane (Grubstake Rd). You can’t miss them, they are everywhere!
Star, ID, where we had swarms of Pine Whites’ for around two weeks and then quite a few dead adults lying around yards, etc. I still have not seen any activity of the Caterpillars on the Pines behind my home. I look every day and nothing so far.
Hi Everyone,
I logged in to my work programs and applications this morning and around 11:00 a.m. MST Pine White Butterflies started to show up around the Pine trees behind my house. Only a couple at first, but their numbers are beginning to increase. I will keep you all updated.
I live on the south side of Lost Horse Creek in the pines and they seem to be as many this year as last. Incredible.
Just found the caterpillars today, we live south of Canyon City,Or how do you get rid of them? Spray, if so what? Last year it was millions of butterflies, they were pretty at first then we found out what they were.Have a good one….
I am very concerned that with the thousands of Pine White Butterflies I see all over the Bitterroot Valley. I feel that there should be more concern towards thinking of mitigating the possiblity of all the damage that will be done in 2012 when the larve from this years batch comes out. It will be 10 times worse than this year and last. The Pine Beetle has done so much damage, now this! They might look pretty, but an infestation this bad can not have a good outcome. Is anyone doing anything about it??? Anywhere?
Well it has been probably two weeks or so since I updated you on the Pine Whites’ in my backyard. I have only witnessed 4-6 adults around each Pine tree; nothing more. In fact, I found one dying today and it was a female. Before last Winter there were many. I do not think the eggs made it through the winter. We did go a couple times below zero this past Winter. Out Pines are extremely lush, due to the lengthened Spring weather this year. There are Yellow Jackets, Ambush Bugs and other types of Wasps constantly patrolling the Pines, so they may have something to do with it also; not to mention the bird species that frequent my Pines. I will keep my eye out and see what happens.
We have a major infestation of the butterflies in Harney County (Eastern Oregon)… I’m wondering…it seems in the last two years the infestation seemed to come with “longer-than-usual” winters…are the natural predators (chipmunks) “sleeping in” when the larvae are out and about? Just wondering
Have lots of pine trees. Different kinds. Lots an d lots of these butterflies have been roaming all around ours and the neighborhood. Am concerned as others, about potential dammage, as our trees have lots to do with our landscape. There have been to many of them to not notice. Where does one go to find out if we should spray or not and if so when?
MarkK
Forgot to mentin I’m in Boise, Id. Foothills. I have never in the past seen any caterpillers this year or ever before. I have some damage previously to spruce. The ends of the evergreens wasted and don’t develop. I suspect this, but never seen caterpillers?
I just a soon spray if possible, rather than take chances, these trees are 40′ +. What and when?
Mark
to all:
just found this site. Very helpful and answered my questions.
http://extension.oregonstate.edu/mwm/w10fhmbutterfly
Best to you all, and thanks for having this site. Very usefull and I will keep up with it.
Gues I’ll be spraying next spring, and will update with results and observations.
MarkK
Interesting that I came across this thread as I tried to identify the hundreds of these white butterflies around here. By the way, ‘here’ is Cascade, Idaho. Thanks Mark for that link!
Just found your website. We had the pine white butterflies in the Tri-Cities, WA (Richland, Pasco, Kennewick) area last summer, and this year they are back again. We started noticing them a few days ago and today there are dozens fluttering around our red and white pine trees in the yard. They are all over town as well. Beautiful! Thanks for all the interesting info. Mary L
Update: Today noticed more Pine Whites’ showing up around all the Pines’. Not sure if their drifting in on the wind or they are hatching out of their pupae state amongst the pine trees. There is not nearly the numbers you have all discussed, but from 2-4 to around 15-20 shows a small percentage of increase. Our pines are so lush right now. I hope their Caterpillars do not destroy these trees. By the way, I thought I would share this with the group. This past weekend was the Western Idaho Fair in between Boise and Garden City, Idaho. They had a Butterfly House and around 7:30 p.m. last day of the show they opened up the front of the enclosure and those who wanted to were allowed to set free the Butterflies. I released 10 Monarchs and around 25 Painted Ladies; two pairs of which were already copulating. The Monarchs’ were the coolest to watch. When released they would flutter at an upward angle into the sky and get so high they would then be out of sight and other would fly above all the obstacles and catch an air current and head north quickly. My guess, they were continuing on their migration path. The Painted Ladies would just take off to the nearby fields. It was a nice experience for such a miserable hot day. Until the next update…Semper Fidelis!
I forgot to mention the Yellow Jackets and Polybiine Paper Wasps have been extremely active patrolling the pine trees. Maybe they are a natural predator of these Caterpillars. Anyone know?
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