What is MilkweedWatch?

The MilkweedWatch program asks members of the public to assist researchers and citizen groups concerned with the health of monarch butterfly populations by identifying the location of milkweed plants, which are crucial for monarch reproduction in Canada. The data you submit will assist in the monitoring of the presence and abundance of milkweed, and help researchers and conservation groups protect, preserve and foster milkweed across Canada. Your observations make a difference!

Why watch for milkweed plants?

Milkweed plants are the primary source of food for caterpillars of the monarch butterfly (Danaus plexippus). The monarch is easily Canada’s most recognizable butterfly, and can be found each summer in the southern areas of every Canadian province. Adult butterflies lay their eggs on the underside of milkweed leaves. Within a week, caterpillars hatch from the egg and feed on the milkweed leaves for approximately two weeks. The caterpillar then hangs upside down from a leaf, attached by a silk thread, and forms a chrysalis, inside which it will pupate (i.e. transform into a butterfly). The adult butterfly emerges within two weeks, and will repeat the reproductive cycle. As autumn approaches, adult monarchs migrate south to the US and Mexico, where they spend the winter and reproduce.

The milkweed plant is the key to the monarch’s success. Milkweeds come in over 150 different types, but share a common trait of being mildly toxic. Most animals avoid eating milkweed, but the monarch caterpillar is able to do so safely. Because it eats milkweed, the caterpillars ingest and accumulate the milkweed’s toxins, making both the caterpillar and the adult less palatable to birds and other predators.

North America’s monarch populations have declined in recent decades. This decline is attributable to a variety of factors, including habitat loss in the monarchs’ overwintering areas, declining availability of wildflowers in Canada and the US, parasites, and pesticides. Another important factor is a decline in milkweed in many parts of North America where herbicides are used on agricultural fields. We must maintain a healthy milkweed population in Canada, which provides an important buffer against future monarch population losses.

Your help is needed

Help scientists and conservation groups monitor, protect and grow Canada’s milkweed population by recording in Milkweed Watch where milkweed is found. It’s easy to do. Using your smartphone or home computer, record any locations you find milkweed, in your yard, neighbourhood or local park, on farmland or at roadsides. Milkweeds are easy to identify, and there are only five species commonly found in Canada. While there, look and see if there are any butterflies and, gently, check leaves for caterpillars, eggs or chrysalises. You can record these, too, in MilkweedWatch.

Ready to watch for Milkweed?

MilkweedWatch is co-sponsored by Ontario Nature!

Ontario NatureOntario Nature, a charitable organization, has been protecting wild species and wild spaces through conservation, education and public engagement since 1931. We have a number of campaigns including pollinators and a listing of volunteer opportunities in our Directory of Ontario Citizen Science. We are there when nature needs us most.

Researcher Profile

Dr. Ilona Naujokaitis-Lewis

Dr. Naujokaitis-Lewis is a landscape ecologist, conservation biologist, and naturalist. She works as a Research Scientist with Environment and Climate Change Canada and is based at the National Wildlife Research Centre at Carleton University. Her research program is motivated by the grand challenge of improving our ability to predict how biodiversity will respond to global change. Her research addresses questions such as how are climate change and habitat loss affecting wildlife species and the habitats they rely on, what species and ecosystems are most vulnerable to climate change, and how should we prioritize conservation actions for climate-vulnerable species. She conducts observational and experimental studies, simulation-based experiments, and uses modeling to answer complex applied ecological problems. The outcomes of her scientific research are used to identify effective conservation strategies, including where, when, and how long to implement actions that help to conserve biodiversity.
Much of Dr. Naujokaitis-Lewis’ current research is focused on understanding causes of native pollinator declines. She spends a lot of time outside examining the role of native vegetation in providing thermal refugia for butterflies, bees and birds, and how a changing climate and patterns of land-use and land-cover in human-modified ecosystems affect biodiversity. As part of this work, she is researching the monarch butterfly and their host plant (milkweed, Asclepias species), including how climate change and land-use practices are affecting where and when monarchs and milkweed are found. Her research relies in part on data collected by citizen science projects like MilkweedWatch.
You can learn more about her research at her home page: https://inlewis.wordpress.com/

Financial support for the creation of MilkweedWatch was provided by Environment and Climate Change Canada