CVC Butterfly Blitz 2020's Journal

October 09, 2020

Butterfly Blitz 2020 wrap up blog post

Hello Butterfly Blitz participants,

Just wanted to send a quick note to point out that there is a brief summary of the 2020 project on the CVC blog:

I hope that some of you will be able to enjoy some time outside this weekend, and maybe add a few more butterflies to your list for the year.

Happy Thanksgiving!

Posted on October 09, 2020 18:42 by lltimms lltimms | 0 comments | Leave a comment

September 15, 2020

Observation of the week – September 7-13

The second last OOTW for the 2020 Butterfly Blitz is a great example of a familiar species, a Monarch butterfly seen by @lisachen1.

Lisa saw this Monarch in the sunflower field at Lakeview Park in Mississauga. She says, “I also saw 2-3 other monarchs in the park, I suppose feeding up for their long migration to Mexico.”

As Lisa says, most Monarchs in our area are getting ready to fly south for the winter. These butterflies need food, like flower nectar, and safe resting spots to power up for their flight. Habitat that provides these things is especially important along the lakeshore, as the butterflies need to make it all the way across Lake Ontario before their next stop.

CVC works to protect and restore habitat along the lakeshore throughout our jurisdiction, to provide habitat for migrating species like Monarchs as well as support many other types of biodiversity. We have recently gone one step further and are creating a new area of natural habitat on the lakeshore – just south of Lakeview Park where Lisa saw her Monarch.

When it is completed in 2025, Jim Tovey Lakeview Conservation Area will contain 26 hectares of green space along the lakeshore. In addition to trails that allow connected access to the lakeshore, this green space will include naturalized streams, wetlands, forests, and meadows. It will provide habitat for many plants and animals, including Monarchs as they migrate south in the fall. It will be a great place for future Butterfly Blitzers!

If you can’t wait until 2025 for Jim Tovey Lakeview CA to be ready, why not start your own habitat creation project close to home? That is what Lisa has been doing: “My friends and I have been planting new pollinator gardens this summer and watching for eggs, caterpillars, and butterflies!”. Have you been doing something similar? Let us know!

Posted on September 15, 2020 13:10 by lltimms lltimms | 0 comments | Leave a comment

September 09, 2020

Observation of the week – August 31 to September 6

Greetings, Butterfly Blitz enthusiasts. While we are nearing the end of the Butterfly Blitz for 2020, its nice to see the continued effort in making observations. This past week we jumped up to 64 total species for this year’s project – four more than in 2019!

Before we get into the OOTW, a quick update on the wrap-up event. Based on the participant survey results, we have decided to hold the event virtually instead of in person. The date is still set for the morning of Saturday, September 19th. Look to your inboxes for an invitation and more details by the end of this week. And please get in touch if you’re not on the email list and want to attend: or

Now onto our OOTW, a Compton Tortoiseshell seen by participant @betcrooks. Laurie (aka @betcrooks) saw this butterfly at Sheridan Meadows in Mississauga, one of her regular butterflying spots.

As Laurie remarked in her observation notes, Compton Tortoiseshells are having a good year. Larger than usual numbers of these butterflies have been seen here in the Credit River Watershed and across the province. This is in contrast to some closely related species that have been seen in lower than usual numbers, like noted on this Painted Lady that Laurie saw on the same day as the Compton.

Compton Tortoiseshell numbers are known to fluctuate from year to year, but as far as I can tell, no one really knows why. Their reproductive rates and population sizes may be highly dependent on weather and other factors, which could cause such fluctuations.

Like other butterflies that overwinter as adults, Compton Tortoiseshells are one of the first butterflies seen in the early spring in Ontario. Laurie and others often see them feeding on tree sap at Riverwood in March and April, as in this observation. They are known to spend the winter inside buildings such as garages, cottages, and outhouses as well as natural locations such as inside tree holes and under the bark.

Adult Compton Tortoiseshells that emerge in the spring mate and then die, and their offspring emerge as adults in the early summer. Those butterflies live for up to another ten months – through the summer, fall, winter, and early spring!

One way that Compton Tortoiseshells can live for so long is by slowing their bodies down to rest in the summer as well as the winter. This process is called estivation, and it is the summer equivalent of hibernation. Estivating butterflies may periodically emerge throughout the summer to feed, which may occur more often if the weather is particularly hot and dry.

More Compton Tortoiseshells than usual is just one of the interesting butterfly stories from 2020. At the wrap up event on September 19th, we will discuss some of the other butterfly patterns we have seen this summer. What have you noticed this year? Let us know!

Posted on September 09, 2020 18:02 by lltimms lltimms | 0 comments | Leave a comment

August 31, 2020

Observation of the week – August 24 to 30

Today’s OOTW features a new species for the 2020 Butterfly Blitz – the Common Buckeye. Darcy McNamee (aka @darcy16) observed a mating pair of them in the tallgrass prairie at Jack Darling park in Mississauga.

Darcy works for the Woodlands and Natural Areas team at the City of Mississauga and was doing maintenance in the prairie when he noticed the pair fly by. He quickly snapped a photo and used iNaturalist to help confirm the species.

Common Buckeyes are referred to as breeding migrants in Ontario. They are not considered to be a resident species because they do not spend the winter here.

Adult Common Buckeye butterflies spend the winter in the southern U.S. and Mexico and fly north each year in the spring. They are found breeding throughout the northeastern U.S. in the summer and fall, and in most years they are also found breeding in southern Ontario. In rare years with the right conditions they can move even further north; they are occasionally found in Thunder Bay – including this year.

If the Common Buckeye's migratory habits sound a bit like the Monarch butterfly to you, you may not be surprised to hear that the two species are related. Several other breeding migrants occur in the same family, including the Painted Lady, American Lady, Red Admiral, Question Mark. None of these species can survive our freezing winter temperatures in any of their life stages.

Marc Johnson (@marcjohnson) and his family also observed several Common Buckeyes at Jack Darling this weekend. It seems that we have a small population of these beautiful butterflies at Jack Darling park.

The tallgrass prairie at Jack Darling where the Common Buckeyes have been seen is a special restored natural area in Mississauga. Tallgrass prairies were once more common in our area but have largely disappeared since settlement of the region. Tallgrass prairies require maintenance, including occasional controlled burns, to ensure that they are taken over by invasive and woody plants. The effort is worth it, as the plants, insects and other animals found in tallgrass prairies are often not found in many other places.

If you’re going to see if you can find the Common Buckeyes at Jack Darling, take some time to enjoy the tallgrass prairie and also look at the prairie wildflower garden, which supports many other butterfly species.

Posted on August 31, 2020 14:58 by lltimms lltimms | 0 comments | Leave a comment

August 24, 2020

Observation of the week – August 17-23

Good afternoon Butterfly Blitz participants. We are into the home stretch of the 2020 Butterfly Blitz, with only four weeks left to add to your butterfly observations.

We are starting to get into the late butterfly season, with a different mix of species around. Maybe you can add an Orange Sulphur to your list, or maybe you will see a Common Buckeye or a Fiery Skipper. We can’t wait to see what you find!

Our twelfth OOTW is this Great Spangled Fritillary by Christine Elliott (@c-elliott).

Christine saw this beautiful butterfly in the pollinator garden at Willow Park Ecology Centre in Norval. She says, “The first thing that struck me when I saw it was the size, it was huge! With the wings open it reminded me of other very large butterflies like the Monarch.”

Although Christine normally uses Rick Cavasin’s pocket guide for butterfly ID, she didn’t have it with her at Willow Park. Says Christine: “This is the only Fritillary species that I've seen in person, so I relied on iNaturalist to confirm my hunch that it was a GSF.”

Great Spangled Fritillary is a good guess if you see a fritillary, as it is the most observed species of that group in our region – especially in somewhat urban areas. When trying to separate it from other species, seeing the underside of the wings is key. Great Spangled Fritillary has a relatively large pale-yellow band on the hind wing, whereas other fritillaries have a narrow yellow band.

The caterpillars of Great Spangled Fritillaries eat the leaves of violets, like all fritillary species you can find in our area. Great Spangled Fritillary females lay their eggs near, but not on, violets. This is because the caterpillars don’t actually eat after they emerge from the egg – they bury themselves in the leaf litter to spend the winter and then begin feeding once it warms up in the spring.

If you have native violets in your yard and you would also like to see Great Spangled Fritillaries there, do not clean up the leaf litter in your garden until early spring. If you remove the leaves, you will also remove the caterpillars and many other insects that spend the winter there.

Check out this page from the Xerces Society for Invertebrate Conservation for more information on 'leaving the leaves'.

Posted on August 24, 2020 19:21 by lltimms lltimms | 0 comments | Leave a comment

August 21, 2020

Wrap up event survey, project end date change, & annotation notes

Happy Friday Butterfly Blitzers!

We interrupt our regular OOTW schedule to bring you three short administrative updates about the 2020 CVC Butterfly Blitz.

(1) We will be sending out an email in the next few days asking for your opinions on attending an in-person wrap up event on September 19th. We’ve been making plans to hold this event to celebrate our Butterfly Blitz efforts this summer in a way that follows all provincial and local regulations regarding COVID-19 guidelines for outdoor gatherings. However, since it’s been a while since we’ve all been able to get together in person, we want to check in to see how everyone is feeling.

The event will be hosted outdoors at Small Arms Inspection Building in Mississauga. It will involve a review of the findings of the 2020 Butterfly Blitz, the presentation of participant awards, and a guided walk and butterfly survey around the property.

If you are a member of this project on iNaturalist but not on our email list, please get in touch with us at either or We will add you to the email list to ensure you receive the survey and any follow up emails.

(2) You may notice a change in the end date of the CVC Butterfly Blitz 2020 iNaturalist project. It was set at September 26th, but we are moving it to September 19th to match the date of the wrap up event. This won’t affect anything in terms of the project leaderboard but is important to note in case you were planning one big last Butterfly Blitz effort in the week of September 20th to 26th!

(3) You might have noticed that I often add an insect life stage observation field note to your observations. I thought I should explain why I do this, since a few of you have asked.

First, I go through every observation added to the project – so that I can help add identifications, see what butterflies are being found, and to help choose the OOTW. Adding the life stage helps me to know that I’ve looked at the observation.

Second, knowing what life stage a species was observed as can be very helpful for certain analyses. Adding the life stage as an observation field makes it easier to use when the data is downloaded from iNaturalist, compared to adding the life stage in the annotations section. This is why I may have added the life stage as an observation field even if you’ve already added it as an annotation.

If you ever have a question about the project, please reach out – we love to hear from you.

Posted on August 21, 2020 16:58 by lltimms lltimms | 0 comments | Leave a comment

August 17, 2020

Observation of the week – August 10 to 16

Our 11th OOTW is this Clouded Sulphur seen by Bob (aka @bob15noble).

Bob’s beautiful photos will be familiar to those that participated in last year’s Butterfly Blitz. The composition of this photo and the amount of detail you can see on the butterfly are wonderful. Look at those green eyes!

Clouded Sulphurs are present all summer in our area but become particularly plentiful later in the season. At this time of year, it is common to see dozens of Clouded Sulphurs flitting around when out for a walk in a meadow or along the side of a road. Bob saw this Clouded Sulphur in a meadow next to the Caledon Trailway, drinking nectar from a Viper’s Bugloss flower.

If you look at your butterfly field guide, you’ll see several Sulphur species that look very similar. Some of these are southern butterflies that occasionally move up into Ontario (e.g. Cloudless Sulphur) and some are northern butterflies that occasionally move south (e.g. Pink-edged Sulphur).

In our area, the two most frequently seen Sulphurs are the Clouded and Orange, with Clouded Sulphur being the most common. The easiest way to tell Clouded and Orange Sulphurs apart is by getting a view of the upper side of their wings. The Orange Sulphur is orange coloured on the upper side, while the Clouded Sulphur is yellow with only a small orange dot on the upper side of the hind wing.

Unfortunately, Sulphurs rarely rest with their wings open, so you may need to catch them in flight to see the upper sides. If you are only able to see the under side, you can base your identification on whether you can see any orange on the fore wing. If not, like in Bob’s photo, it’s probably a Clouded Sulphur.

Besides having some of the most beautiful photos in the 2019 Butterfly Blitz, Bob won the prize for most observations. This year, Bob has generously donated some of his photos to serve as prizes for the 2020 Blitz.

We have six beautiful photos of butterflies in the Credit River Watershed ready to go for the participants that come first in the categories of most observations, most species observed, rarest species observed, best photo, most participation, and a lucky day prize. These prizes will be presented at our wrap up event in September – more details on that event will be coming soon.

In the mean time, you can check out more of Bob’s photography on his website.

Posted on August 17, 2020 16:02 by lltimms lltimms | 0 comments | Leave a comment

August 10, 2020

Observation of the week – August 3 to 9

Hello butterfly enthusiasts. Our 2020 Butterfly Blitz passed a milestone on the weekend – we reached 61 species observed so far this year, which is one more than was found in our 2019 project! Amazing!

Thank you so much everyone for all your efforts in getting outside and reporting the butterflies you see. There is still over a month left in the 2020 Butterfly Blitz, so there are many more opportunities for you to add to our project.

In the meantime, we’d like to tell you about our 10th OOTW – an Eastern Tailed Blue seen by participant @ejankowski. Eugene (aka @ejankowski) is new to butterflies this year and has been taking some very nice photos of butterflies all over the province. I like how you can see both the upper and under sides of the Eastern Tailed Blue’s wings in this photo, as well as its beautiful black and white antennae.

This Eastern Tailed Blue was seen at the end of a butterflying trip to the Elora Cataract Trail, as Eugene and a friend were heading back to the car. Eugene says: “We had seen the species on the previous Sunday on Pelee Island so we recognized it immediately.”

The Eastern Tailed Blue is one of the butterfly species in our area that is like that – once you identify one, you feel pretty confident in identifying the next one you see. They are more common now than they were earlier in the summer, so keep your eye out if you haven’t seen one already. You might find one in an old field, in your backyard, or even on a roadside like Eugene did.

While you’re out there looking for blues, keep your eyes open for a recently introduced species – the European Common Blue. The first Canadian sighting of this European butterfly was in the Montreal area in 2005, and the first ones in the Toronto area were only seen last year. So far there has not been an observation of the European Common Blue in the Credit River Watershed, but it may very well be here.

The European Common Blue looks superficially similar to the Eastern Tailed Blue, but there are some important differences. Compared to the Eastern Tailed Blue, the underside of the European Common Blue’s wings have way more orange spots and are a brownish background colour vs. the grayish of the Eastern Tailed Blue. Also key is that the European Common Blue does not have a ‘tail’ coming off of its hind wings. You can see pictures at this link .

These days, the first detections of introduced species are commonly made by citizen scientists using platforms like iNaturalist. Whether it’s a species like the European Common Blue that may not have much ecological impact, or one like the Spotted Lanternfly that has the potential to be very damaging, data collected by people like you getting outside and recording what you see can be very important.

Posted on August 10, 2020 17:33 by lltimms lltimms | 0 comments | Leave a comment

August 05, 2020

Observation of the week – July 27 to August 2

How many of you can say that you combine butterfly watching with exercise? This week’s OOTW, a Black Swallowtail, was seen by Deb (aka @hockeydoc13) while doing biceps curls in her backyard. We were even more impressed to learn that Deb very diligently finished her set before grabbing her phone to take pictures of the butterfly!

The Black Swallowtail was easy for Deb to identify using her ROM Butterflies of Ontario field guide, especially since it seemed very interested in her veggie garden. Deb says: “It stated in the book that Black Swallowtails like carrot family plants, so it made perfect sense why it kept returning to the carrot plants in my garden.” In fact, in the second picture of Deb’s observation, you can see the butterfly is laying eggs on the carrots – so there may be little caterpillars there sometime soon!

Black Swallowtails are often seen in backyard gardens like Deb’s, where their caterpillar foodplants are growing. They can even sometimes be considered pests by people who would rather keep their parsley, dill, fennel, and carrots to themselves.

Interestingly, these cultivated hostplants are all non-native species that Black Swallowtails have adapted to use. Before the widespread establishment of these and other non-native plants in the same family (e.g. Queen Anne’s Lace), Black Swallowtails were probably much less common than they are now. They also would have most often been found in wetland areas instead of the old fields and gardens where they are now found commonly.

If you find Black Swallowtail caterpillars eating your veggies and don’t want to share, you could consider moving them to a patch a Queen Anne’s Lace or buying them some parsley to eat – be sure to rinse the leaves well to remove any pesticides.

Deb noticed something else about the butterfly that also caused us to choose it as the OOTW: “I was impressed at how well it was still able to fly with a big portion of the hindwing missing.”

That missing bit of wing is the sign of a bird that got unlucky. You often see Black Swallowtails (especially females, like this one) with signs of bird strikes on that part of their wings. Like the hairstreaks that we discussed in OOTW#7, this is probably because the eyespots there confuse birds into thinking that they are attacking the head.

The next time you’re outside getting some exercise, keep your eyes open for butterflies. And let us know what you see!

Posted on August 05, 2020 17:00 by lltimms lltimms | 0 comments | Leave a comment

July 29, 2020

Observation of the week – July 20-26, 2020

We are particularly excited about this week’s OOTW – a Broad-winged Skipper seen by participant @uofgtwitcher.

This is only the third record of Broad-winged Skippers in the Credit River Watershed – with the other records being from the Acton and Georgetown areas.

Broad-winged Skippers tend to stick close to patches of their host plants, which are broad leaved sedges, including lake sedge (Carex lacustris). These sedges are often found growing in narrow strips along roadsides or at the edge of rivers and other wetlands.

That’s where Andrew (aka @uofgtwitcher) saw this Broad-winged Skipper, at the edge of Birchwood Creek on the east side of Jack Darling Park, in what Andrew calls a “tiny piece of extraordinary habitat.”

There are a few wetland butterfly species in our Watershed that are rarely seen but can be found in large numbers if the habitat is right. These butterfly species depend on high quality wetland patches that support their host plants.

Through the efforts of Butterfly Blitz participants, we are getting a better idea of where these species can be found exactly in the watershed. Some species seem to be restricted to only one location, while others can be found in a handful of locations. These habitats are special places, and CVC will use information from the Butterfly Blitz to help protect and restore them.

And that brings us to the other exciting thing about this observation - the Broad-winged Skipper was seen in Jack Darling Park, on the lakeshore in Mississauga. It shows that habitat for uncommon butterflies can be found in urban areas when it is protected and maintained.

As Andrew says, “it is a gorgeous, albeit tiny area and I hope it can be preserved for future generations to see what “once was” in the GTA. The stream was flowing, the pollinators were stirring and the Joe Pye-Weed was fully in bloom. The perfect end to a day of exploration in an area of the lakeshore that I spent countless hours wandering as a young boy.”

Posted on July 29, 2020 13:09 by lltimms lltimms | 4 comments | Leave a comment