The FWG is participating in Mission Monarch, a survey of Monarch caterpillars across Canada…

by Sandy Garland

Just as we were about to give up hope, we noticed this large caterpillar peaking over the edge of a leaf that it was systematically devouring.

Last Saturday (July 22), Daphné Laurier Montpetit of Montréal’s Insectarium gave a workshop at the FWG to tell us about a new initiative. The Insectarium wants to find out the best conditions for Monarch reproduction, and they want help.

Through Mission Monarch, hundreds of people across the country will search for Monarch caterpillars and report their findings online. From the data, biologists hope to answer some questions: are big fields of milkweeds better that isolated smaller patches?  do Monarchs need a certain density of milkweeds for successful reproduction? when does the 4th generation – the ones that fly to Mexico – begin in Canada?

We learned a lot about the Monarch butterfly, its life cycle, its needs, and some of the problems it faces. Then, we had a chance to go outside and participate in a mini-mission. We’ve seen several Monarchs at the FWG this year, far more than in previous years, so off we went to inspect our milkweed plants for signs of reproduction. Our group of a dozen or so participants checked about 130 plants. No caterpillars, but we found 3 eggs!

The real mission begins

But that’s not the end of the story. Mission Monarch holds an annual blitz from July 29 to August 6 to “capture the state of Monarchs’ breeding habitats in Canada.”

As keepers of a certified Monarch Waystation, the FWG wanted to do its bit, so we invited our Facebook group to come on a mission to the milkweed fields south of the Ottawa airport – today and next Saturday.

Today’s mission was small, but lots of fun, thanks to Jim and Mary (pictured above). Unfortunately, although we saw at least 4 Monarch butterflies, we could not find any eggs or caterpillars.

We DID find many other interesting creatures on milkweed plants, however, including the long-horned milkweed beetle, lots of earwigs, various spiders, katydids, Gray Treefrogs, and others.

This long-legged katydid (Scudderia sp.) is almost invisible on a milkweed leaf.


Ambush bug


One of several tiny Gray Treefrogs (Hyla versicolor) found on milkweed plants.

Disappointed and rather tired from working away in the hot sun, we decided to call it a day. But then we were lured by another field, with even more milkweed plants. This time, we were lucky enough to spot a caterpillar immediately.

We think this large Monarch caterpillar must be in its final instar – just before hanging upside down and doing a final moult into a chrysalis.

Pretty exciting, but also a bit of a mystery. We had been looking for signs of eating – holes or edges missing from leaves – as a clue to the presence of caterpillars. But the leaf the caterpillar was on was the only one showing such signs. And all other plants in the vicinity seemed intact. We definitely have more to learn about this amazing insect!

If you’d like to join us next Saturday, please meet at the FWG’s resource centre at 1:30 pm. We’ll carpool or drive together to the milkweed fields and spend about an hour looking for caterpillars.