California Tortoiseshell: All You Need to Know for Butterfly Enthusiasts

The California Tortoiseshell is a fascinating butterfly species native to the western United States.

With its bright orange-brown wings, dark markings, and two-inch wingspan, this eye-catching insect is hard to miss when it takes flight.

However, when perched, the Tortoiseshell can be more difficult to spot due to its mottled brown wing undersides that act as a camouflage against predators.

California Tortoiseshell

California Tortoiseshell

This butterfly is quite particular in its choice of host plant and habitat.

Adult California Tortoiseshells lay their eggs only on various species of wild lilac (Ceanothus).

This exclusive relationship between the butterfly and wild lilac plants has an essential impact on their life cycle and overall survival.

California Tortoiseshell Overview

Appearance and Wingspan

The California Tortoiseshell, a butterfly species, has a vibrant appearance with orange-brown wings adorned by dark markings.

Its wingspan measures around 1.25 to 2.75 inches.

  • Bright orange-brown wings
  • Dark markings
  • Two-inch wingspan

Nymphalis Californica

Also known as Nymphalis Californica, the California Tortoiseshell belongs to the Brush-footed family.

As part of the family, the California Tortoiseshell’s fore-legs resemble hairy stumps2.

This unique attribute sets it apart from other butterfly species.

California Tortoiseshell

Habitat and Distribution

California Tortoiseshell butterflies have specific preferences when it comes to host plants and habitats.

The butterfly can be found from British Columbia south along the Pacific Coast to as far as Baja California Norte, east to Montana, Wyoming, Colorado, and New Mexico.

The adults lay eggs exclusively on various species of wild lilac (Ceanothus). This is where the immature butterflies thrive.

Life Cycle of the California Tortoiseshell

Eggs and Caterpillars

The life cycle of the California Tortoiseshell starts with the adult butterflies laying their eggs.

Female adults specifically choose to lay their eggs on various species of wild lilac (Ceanothus) which act as the host plants for the immature butterflies1.

  • After hatching, the caterpillar stage begins.
  • Caterpillars feed on the host plant, developing quickly.

Pupa and Adult Butterfly

Once the caterpillar has completed its development, it forms a pupa to undergo metamorphosis1. During this stage:

  • The transformation into an adult butterfly takes place.
  • The California Tortoiseshell emerges as a fully-developed adult.

Features of the adult California Tortoiseshell:

  • Bright orange-brown wings2.
  • Dark markings on the wings2.
  • Two-inch wingspan2.

The adults play a crucial role in pollination, contributing to the overall health of their ecosystem.

Host Plants and Feeding Habits

Ceanothus and Snowbrush

California Tortoiseshell butterflies are known to be quite selective when it comes to their host plants.

Adults primarily lay their eggs on different species of wild lilac, also known as Ceanothus.

Snowbrush (Ceanothus velutinus) is one such species, often found in the canyon and high-altitude environments.

Defoliation and Larval Densities

These butterflies may occasionally cause defoliation, especially when larval densities are high.

As the larvae feed on their preferred host plants, they can strip the leaves off Ceanothus species.

Predators and Defense Mechanisms

The California Tortoiseshell, with its vibrant hues and fluttering flight, is not just a delight for butterfly enthusiasts but also attracts the attention of various predators.

Among the common predators of this butterfly species are birds such as ravens, which are adept at catching these colorful insects mid-flight.

Additionally, spiders, mantises, and other insectivorous creatures also pose a threat to both the adult butterflies and their larvae.

Defense Mechanisms

To counteract these threats, the California Tortoiseshell has developed several defense mechanisms.

One of the primary strategies is its ability to camouflage.

When perched, the mottled brown undersides of the butterfly’s wings allow it to blend seamlessly with its surroundings, making it less visible to predators.

This form of crypsis is particularly effective when the butterfly is resting on tree bark or amidst foliage.

Another defense mechanism exhibited by the California Tortoiseshell is its erratic flight pattern.

The unpredictable nature of its flight makes it challenging for avian predators to track and capture it.

This erratic flight, combined with its ability to rapidly accelerate, helps the butterfly evade capture and escape from potential threats.

Moreover, the caterpillars of the California Tortoiseshell also employ defensive strategies.

When threatened, the larvae can exhibit thrashing movements or release distasteful chemicals to deter predators.

These chemicals are often bitter and serve as a deterrent to birds and other would-be attackers, ensuring the survival of the caterpillar to the pupal stage.

Behavior and Migration Patterns

Population Explosions

The California Tortoiseshell butterfly is known for its occasional population explosions, which can lead to large numbers of butterflies migrating together.

These events are typically associated with an abundance of their primary host plant, the wild lilac (Ceanothus) species1.

Seasonal Migration

California Tortoiseshells are migratory butterflies but their migrations are not as predictable as some other species.

They undergo seasonal migration, which means they travel between different regions depending on the time of year:

  • Winter: They overwinter in sheltered, low-elevation areas
  • Spring: As the temperatures rise, they move up to higher elevations
California Tortoiseshell

Upslope Movement

Upslope movement2 happens when California Tortoiseshells follow the retreating snowline during spring.

This is because their preferred host plant, the wild lilac, is found in higher elevations after the snow melts.

In their upslope movement, the butterflies lay eggs on the wild lilac plants, ensuring the survival of the next generation.

California Tortoiseshell in North America

West Coast and Mountain States

California Tortoiseshell (Nymphalis californica) is a butterfly species commonly found in the West Coast and Mountain States, including locations such as Lassen Volcanic National Park.

Oregon and California are also home to this species.

They are known for their mass migrations, where thousands of individuals might travel between foothill canyons and high elevation locations.

Some features of the California Tortoiseshell are:

  • Orange and brown wings
  • Often mistaken for Monarch Butterflies
  • Favors wild lilac (Ceanothus) as host plants for their immature stage

East Coast States

Though primarily found in the West Coast and Mountain States, California Tortoiseshell may occasionally be spotted in East Coast States such as Vermont, New York, and Pennsylvania.

However, their presence in these regions is not as well-established and less common compared to the areas that experience mass migrations.

Notable Locations

Yosemite and Sequoia

California Tortoiseshell butterflies can be found throughout the Sierra Nevada, taking refuge in numerous National Parks.

In Yosemite National Park, visitors often spot these butterflies, especially during the summer months.

Hikers can witness the beautiful interaction between the tortoiseshells and the diverse plant life.

In Sequoia National Park, the sightings are just as frequent. The California Tortoiseshell butterfly thrives in a variety of habitats, such as forests, meadows, and shrub-covered areas within both Yosemite and Sequoia parks.

Kings Canyon and South Cascades

Kings Canyon National Park, adjacent to Sequoia, shares similar characteristics.

Here, California Tortoiseshells find a healthy habitat for migration and breeding.

Hikers exploring this region can enjoy the bustling activity of these captivating butterflies throughout the warmer months.

The South Cascades region, particularly Lassen Volcanic National Park, is also a hotspot for California Tortoiseshells.

They are often mistaken for the more famous Painted Lady butterfly, but their habits differ.

Where Painted Ladies migrate long distances, California Tortoiseshells tend to stay within the bounds of the local region.

Comparison of California Tortoiseshell and Painted Lady Butterflies:

Feature California Tortoiseshell Painted Lady
Migration Distance Shorter, regional migrations Longer, often transcontinental migrations
Preferred Habitat Sierra Nevada, South Cascades Various, including North America, Asia, Africa, and Europe
Appearance Orange with dark markings, smaller wingspan Orange with dark markings, larger wingspan

In summary, California Tortoiseshell butterflies can be spotted and enjoyed by hikers and nature enthusiasts in numerous National Parks and the South Cascades region.

They contribute to the natural beauty and biodiversity of these well-loved locations.

Comparison with Other Butterflies

Sexual Dimorphism

In the case of the California Tortoiseshell, sexual dimorphism is not easily noticeable.

Both males and females have similar bright orange-brown wings and dark markings, making them difficult to distinguish from one another1.

Monarch

Comparing California Tortoiseshell with other popular butterflies like the Monarch reveals some differences:

Feature California Tortoiseshell Monarch Butterfly
Family Nymphalidae Nymphalidae
Size 2-inch wingspan1 3.7 – 4.1 inches2
Color Bright orange-brown1 Orange, black, and white2
  • Caterpillars: While California Tortoiseshell caterpillars feed specifically on wild lilac (Ceanothus) species3, Monarch caterpillars rely on milkweed plants for sustenance2.
  • Pupae: Both butterflies undergo metamorphosis, developing into pupae before maturing into adults.
Male Monarch

Painted Lady

When contrasting the California Tortoiseshell with the Painted Lady, one can identify these differences:

Feature California Tortoiseshell Painted Lady
Family Nymphalidae Nymphalidae
Size 2-inch wingspan1 2 – 2.9 inches4
Color Bright orange-brown1 Orange, brown, and white4
  • California Tortoiseshell caterpillars prefer wild lilac3, while Painted Lady caterpillars thrive on a variety of host plants, such as thistles and nettles4.
  • Painted Ladies are often seen with a wingspan of up to 3 inches, making them slightly larger than the California Tortoiseshell14.

Conclusion

In conclusion, the California Tortoiseshell is a captivating butterfly native to the western United States, notable for its vibrant orange-brown wings and exclusive reliance on wild lilac as a host plant.

This species exhibits intriguing behaviors, including seasonal migrations and population explosions, and can be predominantly observed in regions like Yosemite and Sequoia National Parks.

Despite facing threats from various predators, the butterfly employs effective defense mechanisms, ensuring its survival and continued contribution to the region’s biodiversity.

Footnotes

  1. Pollinator of the Week: California Tortoiseshell Butterfly 2 3 4 5 6 7 8 9
  2. California Tortoiseshell – U.S. National Park Service 2 3 4 5 6 7 8
  3. https://blogs.oregonstate.edu/gardenecologylab/2018/01/10/pollinator-week-california-tortoiseshell-butterfly/ 2
  4. https://www.insectidentification.org/insect-description.php?identification=Painted-Lady-Butterfly 2 3 4

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – California Tortoise Shell


I tried sending a couple of pics of a butterfly I can’t identify, but the message got bounced back as exceeding your mailbox size. Is there some other way of posting the pics so you could see them?
Grace L. Suarez
Lawyer and Life Coach

Hi Grace
We asked Eric Eaton for help with your Nymphalid, and he quickly provided the following information:
“It is a California tortoiseshell, Nymphalis californica, assuming this was taken in the U.S. Nice image. I think they overwinter as adults, like the mourning cloak does.
Eric”

Letter 2 – California Tortoiseshell

california tortoiseshell
hi there again,
thanks so much for you help with the photos i sent you last night. i did find that b-fly again this afternoon and did get a better photo. it’s not a calendar shot, but it clearly shows that it is the calif tortoiseshell. he was opening and closing his wings, mostly closing, and somehow i managed to get a photo with his wings more open. i was pretty excited. i’ve never seen one before and they are considered rare where i live according to my “butterflies through binoculars, the west” book. again thanks for all your work in helping someone like me id these wonderful creatures. cheers,
venice kelly

Hi Again Venice,
Thanks for updating us with a nice dorsal view of your California Tortoiseshell.

Letter 3 – California Tortoiseshell

butterfly question
hi bugman,
i’m sending two photo’s of a b-fly i saw this afternoon and i thought for sure it was a california tortoiseshell. the dorsal view isn’t a good angle to really id it and the ventral view is very clear but when i looked it up in my books and on the i-net none of the ventral views look like my b-fly. so what do you think it is? his dorsal view looked so california tortoiseshell. can they look different depending on male or female? i saw it not far from nederland colorado, west of boulder in the mountains. and it is july 14 today. i so appreciate your help when you have the time. and i’m going looking for that b-fly again tomorrow to see if i can get a better photo of the dorsal side. thanks for all your help past and present. i just adore your web site, i’m on it all the time. cheers,
venice kelly

hi Venice,
Though your dorsal view is at an angle, enough of the upper wings show to incline us to agree that this is a Calfornia Tortoiseshell, Nymphalis californica, which despite its name, also ranges in most of the Pacific Northwest, and into Idaho, Montana, Nevada, Arizona, New Mexico, Colorado and Utah, as well as some adjacent states. If you get a better dorsal view, please send it to our attention.

Letter 4 – California Tortoiseshell

Subject: Butterfly sighting – Inyo National Forest
Location: Inyo National Forest – Golden Trout Wilderness
August 7, 2017 4:06 pm
Hi Bugman,
While hiking at about 9,000 feet altitude in the Inyo National Forest (Southern Sierra Nevada) we spotted several of this butterfly, mostly on the ground. Thought it might be one of the “Ladies” but the bottom side of the wings were very dark. It’s wingspan was around 2 inches.

Though we didn’t get pictures, we also saw a lot of Yellow Swallowtails, Cabbage Whites and one that looked like a Common Checkered Skipper (light brown wings with white oval spots) but has a wingspan of over 2 inches.
Signature: Jeff Bremer

California Tortoiseshell

Dear Jeff,
This pretty little butterfly with good camouflage when its wings are closed is a California Tortoiseshell,
Nymphalis californica, which you can verify by comparing your individual to this BugGuide image. 

According to BugGuide:  “Adults emerge in June and fly until fall, then overwinter. They fly the following spring until April or May, mating and laying eggs for the next brood” and “Males perch in the late afternoon to look for females.”

California Tortoiseshell

Letter 5 – California Tortoiseshell: Population Explosion

Timothy Lake, Oregon
My son and I went camping at Timothy Lake, Oregon this weekend and saw the most fascinating thing. What seemed like thousands of butterflies EVERYWHERE. It was hard not to hit them as we were driving to the lake. They were on the lake shore in the hundreds.

I believe they were monarch butterflies. I tried to find out if this was a regular occurrence but no one seemed to know anything about it (including the forestry center volunteers).

They seemed to disappear as the sun went down and then come out of nowhere as the weather got warmer. Would you be able to help me find out if this is normal in our area (northern Oregon; Mt Hood area)? Thanks,
Jennifer

Hi Jennifer,
These are California Tortoiseshells, Nymphalis californica. According to the book “Butterflies Through Binoculars: The West”: “This species, often quite rare, has periodic irruptions and migratory movements. In irruption years the butterfly may be everywhere, with the caterpillars completely covering Ceanothus-covered hillsides.”

Letter 6 – California Tortoiseshell Swarm

more on 8/14/2006
Dear Bugman,
Saturday afternoon, 8/19/2006, I was on the summit of the “South Sister,” 10,400, maybe 80 miles south of Timothy Lake, OR. There we saw thousands of Nymphalis califonica flying up the cone and along the rim of the volcanic summit. Perhaps those seen by Jennifer and her son on 8/14/2006? ;o) Attached is a picture taken at the summit. It was awesome to witness!
Martha Perkins

Hi Martha,
Thank you for sending in your photos of this spectacular swarming of the California Tortoiseshell Butterflies.

Letter 7 – Compton Tortoiseshell

Comma Butterfly?
Dear Bugman:
I’ve searched your site high and low, and (unless I missed it) I can’t find this critter anywhere. It appears to be a Comma Butterfly of some type, but I can’t find any in your pics that have the white spots on wings. Can you help me ID this fellow? Thanks in advance!
Robin
SW Wisconsn

Hi Robin,
That was a good guess. This is a Compton Tortoiseshell, Nymphalis vau-album, a near relative of the Comma and other butterflies in the genus Polygonia. The Compton Tortoiseshell is in the same genus as the Mourning Cloak. The caterpillars feed on birch and willow. Thanks so much for adding a new species to our site.

Letter 8 – Compton Tortoiseshell

Hello Mr. Bugman,
I hope you can help me with identifying the attached moth or butterfly. Location near Hamilton, Ontario, April 8th, still some snow in drifted areas, high daytime temperatures mid 50’s. Thank you for your time.
Ron

Hi Ron,
Like its relative the Mourning Cloak, the Compton Tortoiseshell, Nymphalis vau-album, overwinters as an adult and flies with the first sunny warm days of spring, even if there is still snow on the ground. Theses butterflies are not typical nectar feeders, and they will take nourishment from sap that is running from tree wounds in the spring. The common name comes from Compton County Quebec.

Letter 9 – Compton Tortoiseshell

What kind of moth or butterfly is this?
August 10, 2009
I was on a weekend away in Perry Sound Ontario Canada, and spotted this little beauty on a rock by the watter..
Any Idea what it is? It looks like a moth.
Laurie
Perry Sound, Ontario, Canada

Compton Tortoiseshell
Compton Tortoiseshell

Hi Laurie,
The Compton Tortoiseshell, Nymphalis vau-album, is a butterfly.  According to Bugguide it is found in: 
deciduous and coniferous forests; often associated with “cottage country” in the north, overwintering in tree cavities, under eaves, or in garages, outhouses, and cottages. 

BugGuide also indicates:  “larvae feed in groups on willow (Salix spp.), birch (Betula spp.), and poplar (Populus spp.)  adults feed on sap, rotting fruit, and nectar of willow flowers

Letter 10 – Compton Tortoiseshell

Moth ID
Location: Western New York
February 27, 2011 12:41 am
Hi, I found this moth outside of our house on October 10, 2008. We live in Upstate New York, near Buffalo, NY. He was out in the daylight. Can you identify him? Thank you!
Signature: Dawn

Compton Tortoiseshell

Hi Dawn,
Your butterfly, not moth, is a Compton Tortoiseshell,
Nymphalis vau-album , and it appears as though it might be a dead specimen.  We cannot distinguish its antennae from background, it seems as though they are missing.

Letter 11 – Compton Tortoiseshell from Canada

Subject: Really would love positive identification, it means a lot to know of this visitor.
Location: Athabasca, Alberta, Canada
March 16, 2017 9:57 pm
Dear Mr Bugman,
Should you find the time for this identification request, it would be quite a delight indeed. Thank-you for your consideration and guidance.
Seen;
Athabasca, Alberta, Canada
Thursday, March 16, 2017
Is it a butterfly? Is it a moth? It was very much an intended visitor.
Please help me to determine what such beauty found me.
Signature: TannaT

Compton Tortoiseshell

Dear TannaT,
Too bad you were unable to get an image of this pretty little Compton Tortoiseshell,
Nymphalis l-album, with its wings open.  The upper surface of the wings is much more brightly colored, which causes the butterfly to be somewhat flashy while flying, but when it alights, especially among dried fallen leaves on the ground, it blends in perfectly because of its camouflage coloration. 

Here is a BugGuide image for comparison.  Was this sighting recent?  According to BugGuide:  “adults fly from July to November before hibernating, and appear again in May and June to lay eggs.”  If this sighting was just made, and you are having unseasonably warm weather, it is possible this hibernating individual emerged early.

Dear Daniel,
Thank-you mega much for your guidance and timely response.
This sighting was indeed just yesterday, March 16, 2017 at approximately 12:34 pm.
The air is still quite cool with snow on the ground and yet to come in the forecast.
How grateful I am to have been a witness to such a rare delight.
I know it was a sign from above to see her. Perhaps my story is quite alike hers.
I was previously told by a numerologist that March 16 would be the “unexpected beginning
of a change of fate that will certainly be the most beautiful of your life”.
She was a big part of my melting heart.
Thank-you again and again for your help.
-TannaT

Letter 12 – Metamorphosis of a California Tortoiseshell

Subject:  black caterpillar
Geographic location of the bug:  Noth Umpqua area of Oregon
Date: 06/13/2018
Time: 04:44 PM EDT
Your letter to the bugman:  Hi I’ve been having trouble identifying this critter. They showed up June 2, 10 days ago by the thousands. At first they were about 1″ long , now they are around 2″.

I’ve been watching their progress and today I noticed some pupae forming. I had thought they were Ceanothus Silk Moth caterpillars but now I don’t thinks so.
How you want your letter signed:  Thanks Bill

California Tortoiseshell Caterpillar

Dear Bill,
We immediately wrote back to see if you could provide the name of the plant upon which these Tortoiseshell Caterpillars are feeding, because we are certain the genus is
Nymphalis, but we are not sure of the species. 

Our likeliest candidate because they are often found in great numbers is that they are Mourning Cloak Caterpillars, but the caterpillar lacks the red spots found on Mourning Cloak Caterpillars and the chrysalis does not really look right.  According to BugGuide, Mourning Cloak Caterpillars feed on ” primarily willow (Salix spp.) but also other trees and shrubs including Cottonwood (Populus deltoides), Trembling Aspen (P. tremuloides), American Elm (Ulmus americana), Paper Birch (Betula papyrifera), and Hackberry (Celtis occidentalis).” 

Based on images posted to BugGuide, we believe they are probably California Tortoiseshells, and Oregon is well within the range, and since BugGuide states “Larva feeds on various species of wild lilac (Ceanothus),”  knowing the food plant would greatly assist in the identification. 

Our least likely candidate due to your location is the Compton Tortoiseshell because most caterpillars are green, but BugGuide does picture this black individual and BugGuide indicates the range as being “southeastern Alaska and across Canada south of the tundra, south in the west to Montana and Wyoming, south in the east to North Carolina and Missouri known to wander; has been recorded as far south as California and Florida, and as far north as Baker Lake, north of treeline in Nunavut” and also states “larvae feed in groups on willow (Salix spp.), birch (Betula spp.), and poplar (Populus spp.).” 

In recapping, we are leaning toward California Tortoiseshells, and knowing they were feeding on Ceanothus would seal the deal for us.

Metamorphosis of a California Tortoiseshell Caterpillar

Hi Thanks for the response They were feeding on Buckbrush (Ceanothus) and Schoolers Willow. There were people clearing trees and brush from under a major powerline up the hill behind me and they said that the caterpillars completely defoliated over 2 acres of buckbrush.

Yesterday I was still seeing them coming towards our home and on the driveway but it is slowing down and they are attaching and forming  the chrysalis. I’m sure looking forward to seeing them when they emerge. Thanks Bill

Please try to send us images of any adults that emerge.  That will surely verify the species.

California Tortoiseshell Chrysalis

How long will they be in the Crysalis? It’s warming up to the 90’s next week.

Two weeks is a good average, but temperature and humidity may affect eclosion time.

Update:  June 27, 2018
These guys showed up today. Lots of them were in my green house plastic lean-to affair, I opened the ends and chased them out. I have yet to see any action from the one I have in a jar and most of the chrysalis’s have disappeared or been eaten.

I saw wasps harassing them and an orange fly about the size of a house fly eating one. Some out in the woods were still shaking when I approached so they’re still viable I guess. I was expecting to see more but some are still to come I suppose.
Thanks for your help Bill

California Tortoiseshell

Thanks for the update Bill.  Seems this California Tortoiseshell appeared right on schedule.  Here is a BugGuide image to verify its identity.

Letter 13 – Metamorphosis of Compton Tortoiseshell Caterpillar in Canada

Subject:  What is this caterpillar?
Geographic location of the bug:  Winnipeg, Manitoba, Canada
Date: 06/10/2018
Time: 08:30 PM EDT
Your letter to the bugman:  I found this caterpillar climbing on my front door yesterday. (picture 1)  Today I caught him j’ing (picture 2) He has now turned into a chrysalis.   (picture 3)  There is a second one of the same sort at the bottom of my door.

He is green with a dark head and has barbed setae or spikes.   I would like to know what kind of caterpillar he is and what he will become.  I hope you can help me.  Thanks!
How you want your letter signed:  Sherrie

Compton Tortoiseshell Caterpillar

Dear Sherrie,
How lucky are you???? We have identified your caterpillar as a Compton Tortoiseshell Caterpillar,
Nymphalis l-album, thanks to images posted to BugGuide.  The caterpillar and chrysalis are described on BugGuide,:  “Larva: body speckled and spotted white on pale green, yellow and brown, or blackish, with several rows of branched, usually black spines; head also bears many short spines, with one pair larger and branched near the tip.

This is the only Nymphalis species with the pair of branched head horns. Polygonia larvae are similar, though usually with different markings.  Pupae: similar to other Nymphalis and to Aglais species, with two points on head end and two rows of conical projections mostly arranged along the dorsum of abdomen + thorax; plus, one prominent point on the mid-dorsum and more along the sides of the thorax.” 

According to BugGuide, the range is:  “southeastern Alaska and across Canada south of the tundra, south in the west to Montana and Wyoming, south in the east to North Carolina and Missouri known to wander; has been recorded as far south as California and Florida, and as far north as Baker Lake, north of treeline in Nunavut.”  

The chrysalis of the Compton Tortoiseshell is pictured on the John Fowler website.  If your luck continues and you are able to witness the emergence of the adult Compton Tortoiseshell, we would love to have you send us the images.

Pre-Pupal Compton Tortoiseshell Caterpillar

Dear Daniel,
Thank you so much!  I was curious to see what kind of caterpillar it was.  The caterpillar crawled up my front door and decided that was the place to stay.  Ot was interesting to see him in the j.  An hour and a half later he was a chrysalis.

Only assuming it was that long because that is when I came back from shopping.  I now have another one below my front door, so I have the opportunity to witness two emerge.  I hope they do it while I am watching.  Do you know how long they will stay in the chrysalis before they emerge?
Thank you again,
Sherrie

Hi again Sherrie,
The actual eclosion date, the day the adult emerges from the chrysalis, may vary depending upon temperature and other weather conditions, but according to BBC:  “The chrysalis stage varies between species but is usually around two weeks, whilst the caterpillar inside is undergoes metamorphosis into a butterfly.

In order to emerge, they need to be out of direct sunlight, at around 25 degrees and in relatively high humidity.”  According to Woodland Trust:  “Conversion to a butterfly takes place inside the chrysalis – this process can take several weeks.”  According to Sciencing

“Most butterflies take about 10 to 14 days to emerge from their chrysalises.”  Many chrysalides change color just prior to pupation, so that might be a hint that eclosion is near.

Chrysalis of a Compton Tortoiseshell

Update:  June 23, 2018
Hi Daniel,
I ended up having 5 Compton Tortoiseshell caterpillars turn into chrysalis around the front of the house.  You were right their chrysalis do change color prior to eclosion.  I went to get groceries in the morning and noticed that their cocoons had changes color.  I came back and I noticed that one had emerged.  I was gone only 30 minutes.

Sad that I did not get to see the eclosion, just missed it, but happy to see the butterfly resting and finishing his wing development.  Beautiful.  I have included a close up of my newly emerged Compton Tortoiseshell butterfly.

I believe 4 out of the 5 survived and think something happened to the one that cocooned on my front door.  Again thank you for your help identifying my caterpillars.

Eclosion of a Compton Tortoiseshell

Thanks for the update Sherrie.  We really appreciate the images of the adult to add to your previous posting.

You are welcome.  I really wish I had been there a moment earlier to have caught the emergence.  And to have seen it open it’s wings.  I did see one of the ones that had emerged earlier fluttering around the yard, but was too high to get a close up.  Thank you for all your help identifying the Compton Tortoiseshell.  Was happy I could get so close and capture all the detail.
Sincerely,
Sherrie

Letter 14 – Milbert’s Tortoiseshell

All sorts of bugs
Hey there,
I just discovered your site, and it’s wonderful! Just by browsing through your pages I’ve managed to identify many of the unknown bugs I’ve photographed over the last few years. (I have loads of butterflies, a fair number of dragonflies, and plenty more; many of which I’ve managed to identify over the web or in books, but plenty more are still a mystery to me.)

I figured I’d pull out a few of my favorites to send to you–hopefully you can help me identify several of them, and the rest are ones I’ve identified but didn’t see on your site. (Please feel free to edit this, remove some photos, etc.) … This guy’s a Milbert’s Tortoiseshell (pretty hard to mistake these for anything else!)

I encountered at Logan Pass in Glacier National Park, Montana, last summer. I didn’t see any photos of these in your butterfly pages, so I figured I’d share. I encountered quite a few butterflies as well as other beautiful insects in the alpine meadows there, but the Milbert’s Tortoiseshell is definitely the most striking. …

Anyway, I hope you enjoy my photos and can identify/confirm them all. I have plenty more where they came from, so if your inbox isn’t too flooded already, I’d be happy to send more!
Susan B

Hi Susan,
We edited the content of your letter and are posting the Milbert’s Tortoiseshell to our site. In the future, please only submit one identification request per letter than includes any helpful information and will will get back to you if time permits. Thank you for your enthusiasm.

Letter 15 – Milbert’s Tortoiseshell

Do you what type of butterfly this it was on the butterfly bush. The outside wings look like bark and the inside wings had different shades of orange and brown.
Daniel Parsons to bugman
show details 7:21 PM (5 hours ago)
Do you what type of butterfly this it was on the butterfly bush. The outside wings look like bark and the inside wings had different shades of orange and brown.

Tortoiseshell Butterfly

Hi Daniel,
Though we have nothing personal against cellular telephones, we do not care to own one.  We wish Daniel would find a way to make the cell phone submissions utilize our standard form that requires that fields be filled in.  One of our fields is location, and we hate not knowing the location.

Milbert’s Tortoiseshell

We have determined it to be Milbert’s Tortoiseshell based on BugGuide images.  Many of the Anglewing Butterflies have the undersides of the wings patterned like wood camouflage.

Letter 16 – Milbert’s Tortoiseshell

Subject:  Milbert’s Tortoiseshell
Geographic location of the bug:  Kenai Peninsula, Alaska
Date: 09/04/2017
Time: 03:13 AM EDT
From my research I gather this is a common butterfly, but I though you might be interested in a photo of the undersides of its wings. Almost looks prehistoric.
How you want your letter signed:  Jeanne

MIlbert’s Tortoiseshell

Dear Jeanne,
Your images are quite beautiful.  The Milbert’s Tortoiseshell is not considered a rare species, but we have not received an image since 2011.  Furthermore, we love getting submissions from Alaska. 

The Milbert’s Tortoiseshell is considered one of the Anglewing Butterflies, a group that has brown, mottled markings on the underwings that help to camouflage the brightly colored butterfly when it alights and folds its wings near dried leaves and on tree trunks.

Milbert’s Tortoiseshell

Letter 17 – Milbert’s Tortoiseshell: Imago and Caterpillars

Milbert’s Tortoiseshell
Fri, Nov 28, 2008 at 6:43 AM
Hello Bugman:
As another Canadian winter settles in I take cheer in organizing the mountain of photos that accumulate during our short but brilliant summers. Here is another one of my favourite North American butterflies, the Milbert’s Tortoiseshell (Nymphalis milberti).

Not only are they strikingly beautiful, they are also very widespread (most of Canada south of the tundra, and northern and western USA, particularly the mountain states). This adult was photographed in a high alpine meadow in the southern Alberta Rockies, and the larvae are from southeastern Manitoba.

Our winters are long up here and one of the sure signs of spring is the re-emergence of these creatures in early spring. They are around all summer and one of the last to disappear in late autumn, when the adults go into hibernation. Another endearing feature; the caterpillars feed almost exclusively on stinging nettle! Regards.
Karl

Milbert's Tortoiseshell
Milbert’s Tortoiseshell

Hi Karl,
Thank you for sending your excellent photos of two phases in the metamorphosis of the Milbert’s Tortoiseshell as well as the detailed information on the species.  This is an excellent addition to our archive.

Milbert's Tortoiseshell Caterpillars
Milbert’s Tortoiseshell Caterpillars

Letter 18 – Small Tortoiseshell from the UK

Subject: What is this Moth or Butterfly
Location: United Kingdom
July 23, 2016 11:49 am
I took this today in Oxfordshire, UK and wanted to know what it was, thanks for any help in advance.
Signature: Sandra

Large Tortoiseshell
Small Tortoiseshell

Dear Julie,
This is a very exciting posting for us.  We have identified your butterfly as a Large Tortoiseshell,
Nymphalis polychloros.  According to UK Butterflies:  “In Victorian times the Large Tortoiseshell was considered widespread and common in woodland in southern England.

However, this beautiful insect has since suffered a severe decline and there have been less than 150 records since 1951. This butterfly, whose numbers were always known to fluctuate, is generally considered to be extinct in the British Isles, with any sightings considered to be migrants from the continent or accidental or deliberate releases of captive-bred stock.

Several causes of its decline have been suggested – including climate change, parasitism, and the effect of Dutch Elm disease on one of its primary foodplants. The hope, of course, is that this butterfly is able to once again colonise our islands.

Although previously found in many parts of England, Wales and Scotland, the greatest concentrations were in the midlands, south and east of England. This species has not been recorded from Ireland. Recent sightings have come from the south coast, in particular from South Devon, South Hampshire, the Isle of Wight and West Sussex.”

Correction:  Small Tortoiseshell
We just received a comment indicating that this is actually a Small Tortoiseshell,
Aglais urticae, not a Large Tortoiseshell.  According to UK Butterflies:  “The Small Tortoiseshell is one of our most-familiar butterflies, appearing in gardens throughout the British Isles.

Unfortunately, this butterfly has suffered a worrying decline, especially in the south, over the last few years. This butterfly has always fluctuated in numbers, but the cause of a recent decline is not yet known, although various theories have been proposed.”

Letter 19 – Yellow Legged Tortoiseshell from Iran

Nymphalis sp. From Iran
Sun, Mar 29, 2009 at 9:30 AM
Hi… I found this worn piece of beauty on the first days of spring in Tehran, Iran… It was flying elegantly over the river and sometimes sipping sap from willow barks…I’m doubtful between Nymphalis polychloros and N. xanthomelas… There are a lot of Salix. spp plants there… Do you have any idea how can I find its eggs/larvae?
Thanks a lot…
Mohsen Arooni,
Tehran, Iran…

Tortoiseshell from iran
Yellow Legged Tortoiseshell fromIran

Hi Mohsen,
We don’t get many submissions from Iran, so we are very happy to have received your butterfly image. Here in the U.S., butterflies in the genus Nymphalis with markings similar to your specimen are known as Tortoiseshell Butterflies.

Another relative in the genus with distinctively different markings is the Mourning Cloak, known as the Camberwell Beauty in England. Nymphalis species often hibernate as adults, emerging with the first warm spring days.

Willow is a common food plant for North American members of the genus, and we suspect that the same may be true for the Iranian species. Search for the spiny caterpillars on the willow leaves.

Letter 20 – Yellow Legged Tortoiseshell from Japan

Japanese yellow-legged tortoiseshell
I am going through all my old photos, especially of bugs, and thanks to you I have another positive ID! I was in Japan last year and took a picture of this nice docile butterfly. From the link on your site to a Japanese butterfly site I believe it is Hiodoshi-cho the Yellow-legged tortoiseshell. Thanks again!!
Rebecca in Falls Church, VA

Hi Rebecca,
Your research skills should be commended. Your identification of a Yellow Legged Tortoiseshell from Japan looks correct to us. It is awesome that you couldn’t find your answer on our site but followed a link we provided. We would never ever ever verbally bash our serious readership, but we often get marginally perturbed that so many people just send in photos, often with no helpful information, and never bother to search our vast archive for their identifications. More often than not, they don’t even need to look any further than our homepage.

Authors

  • Daniel Marlos

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

12 thoughts on “California Tortoiseshell: All You Need to Know for Butterfly Enthusiasts”

  1. Thanks a lot for your reply… After examining images from the useful website “Butterflies and moths of Europe and North Africa” I discovered that its actually Nymphalis xanthomelas, or “The Yellow legged Tortoiseshell”…
    Yours: Mohsen Arooni, Tehran, Iran…

    Reply
  2. Hi Daniel,

    I believe that this is the Small Tortoiseshell Aglais urticae, which is common in Europe, but which also occurs all the way across Asia.

    Assuming I am correct about the species, the caterpillars feed on the common stinging nettle Urtica dioica and the small nettle <U. urens.

    The butterflies overwinter, often in houses or other buildings, and then come out in the spring, looking a bit worse for wear.

    Mohsen may not start to see caterpillars for a while, because the butterflies need to mate, lay eggs and the eggs hatch and grow a bit before the darkish, somewhat hairy caterpillars are noticeable on beds of nettles.

    I used to raise these butterflies myself when I still lived in England. It’s not easy picking stinging nettles every day for the caterpillars to eat. I used to use a plastic bag as a glove!

    Best wishes, Susan J. Hewitt

    Reply
  3. Hi Daniel,

    I believe that this is the Small Tortoiseshell Aglais urticae, which is common in Europe, but which also occurs all the way across Asia.

    Assuming I am correct about the species, the caterpillars feed on the common stinging nettle Urtica dioica and the small nettle U. urens.

    The butterflies overwinter, often in houses or other buildings, and then come out in the spring, looking a bit worse for wear.

    Mohsen may not start to see caterpillars for a while, because the butterflies need to mate, lay eggs and the eggs hatch and grow a bit before the darkish, somewhat hairy caterpillars are noticeable on beds of nettles.

    I used to raise these butterflies myself when I still lived in England. It’s not easy picking stinging nettles every day for the caterpillars to eat. I used to use a plastic bag as a glove!

    Best wishes, Susan J. Hewitt

    Reply
  4. Hi Susan…
    These are very similar and I’ve raised the small tortoiseshell too!… Ouch!…
    This one has a larger wingspan… Also, it has more spots on the forewing… Plus, there are no blue spots on the forewing margins…
    Thanks for sharing your experiences…

    Reply
  5. Dear Bugman…
    I can’t consider your reply as a scientific answer… I speak persian and common names like “Tortoiseshell” are not useful here… So perhaps knowing the scientific name (international standards) might be more helpful…?

    Reply
  6. Dear Mohsen,
    With all due respect, we realize our response to you was unscientific, because the fact of the matter is, we are not scientists. We have proudly announced on our website on numerous occasions that we are artists with no scientific backgrounds. While we try our best to properly identify submissions sent to us, the fact of the matter is that counting tarsi, dissecting butterfly genitalia (a skill that our favorite author Vladimir Nabokov possessed) and plotting wing veinage is well beyond the scope of our skills. Even within the scientific community, we find that experts in Crane Flies (Family Tipulidae) are often not much help when a person is trying to identify an Assassin Bug (Family Reduviidae) because in our 21st Century world, we have specialists with a narrow scope of expertise. Our website mission, and perhaps we should post our Mission Statement on our website, is “to assist the average person in developing an appreciation of the lower beasts, while doing what we can to correctly identify the family, genus, and occasionally the species of photos submitted to our site.” Sometimes it is not even possible for us to identify the family, and the order will have to suffice. Many of the Mites submitted to our site were merely identified as Mites before an Acarologist assisted us with the proper identifications. While we are sorry that you were disappointed in our unscientific answer, we did what we could, and it seems as though Susan came to your rescue with several possibilities for the proper species.

    Reply
  7. Dear Bugman…
    Forgive me.. I should have read the “About WTB”… Now I realize that we are all students… Learning from each other…
    After reading some books, I’m sure this butterfly is N. xanthomelas…
    Thanks for your informative reply…
    Yours… Mohsen Arooni
    Tehran, Iran…

    Reply
  8. Thanks for writing back Mohsen,
    Your letter has prompted us to try to concisely develop our mission statement, and we would also like to add that we promote a global community of tolerance.
    Have a wonderful day.
    Daniel

    Reply
  9. It’s a Small Tortoishell, which is very common. Note the white on the top tips of the upper wings, and the 3 black blobs.

    Reply

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