I’m not the only one who noticed fewer butterflies this summer. Both on Facebook and in the media, others have made the same observation. It’s disappointing, but is it cause for concern?
What’s going on?
Populations of insects do fluctuate from year to year. Since there were so many butterflies last year, perhaps this year is back to ‘normal’. After the slow start in early summer, I did see more butterflies in the garden in August.
Despite the high numbers of Monarchs here last summer, the overwintering population decreased in Mexico by a whopping 53% (Monarch butterfly population down 53% from last year). One possible cause was the late migration south. Another reason might be the lack of nectar plants en route to fuel their journey, especially due to a drought in Texas.
The first Monarch arrived late this year, on July 12, 2020. 
On Meadow Blazing Star.
Monarchs aren’t the only butterflies missing this summer. There have also been lower numbers of common ones that don’t migrate. Was the weather to blame? We had a late, cold spring. Then in July, the heat was unbearable, unrelenting, and set daily records (Ottawa sets record for hottest July in nearly 100 years). In fact, July was one of the hottest months ever recorded on Earth (If you thought July was hot, you were right: it was one of Earth’s hottest months ever recorded). We also had a severe drought (Canadian Drought Monitor). According to an article in the PENNLive Patriot-News,
“Many species, including Monarchs, will shut down when temperatures get too warm. Monarch eggs do not hatch in very dry conditions and dry weather can also kill milkweed. … There are several studies that have shown that temperatures above approximately 95 degrees Farenheit [35°C] can be lethal to all stages of development and adults are incapable of mating. So that could explain the slow start.”
Rick Mikula, What happened to our butterflies this summer?
Thankfully, once average temperatures and rain returned, we noticed more butterflies in our yard. Whatever the cause, fewer butterflies is another reason to be concerned about declining insect populations and biodiversity loss (As Insect Populations Decline, Scientists Are Trying to Understand Why).
Gallery of butterfly visitors
Even though there were fewer butterflies in the garden, I still managed to get lots of photos of the ones that did stop by. I also raised a few chubby caterpillars outside in a mesh butterfly enclosure to ensure that they survived until adulthood. Such delightful insects!
American Ladies
An American Lady butterfly laying eggs on Field Pussytoes leaves. 
The caterpillars create webbed enclosures to hide from predators. 
An American Lady caterpillar (front) on Pearly Everlasting. 
A well-camouflaged chrysalis. 
New butterflies drying their wings. 
Ready to take flight.
Black Swallowtails
Male Black Swallowtails have a prominent yellow stripe on the inside of their wings… 
…but females have more blue inside their wings. 
I tried, and failed, to protect a caterpillar from predators using an organza bag. One morning, I found a shriveled cat and a black stain on the bag. 
A late instar caterpillar on parsley in my mesh butterfly enclosure. 
A Black Swallowtail chrysalis. 
Drinking nectar from Purple Coneflowers.
Monarchs
Monarchs mating. 
A Monarch laying eggs on Swamp Milkweed. 
A teensy, newly-hatched Monarch caterpillar. 
This cat is getting so big and heavy that it bent the milkweed stem. 
A Monarch chrysalis. 
After leaving its chrysalis. butterflies pump fluid into their wings and dry them before they can fly.
Giant Swallowtails
A Giant Swallowtail soaring around the front pollinator garden. 
Laying eggs on Rue. 
Giant Swallotwail egg on a Rue leaf.
I’ll share more butterfly photos in my next post.
The Corner Pollinator Garden and Wildlife Habitat 
Gorgeous and informative. Thanks.
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Thanks for sharing, hope the butterflies return soon!
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