Look for monarchs


Recognizing monarchs

The Mission Monarch project aims to identify the best habitats for monarch reproduction. How can we find them? By looking for monarch eggs and caterpillars! Because they offer the best clues as to the suitability of a field of milkweed for monarch reproduction, they can help us protect the most productive habitats.

Butterflies undergo complete metamorphosis, meaning they look completely different at every stage in their lives. A butterfly’s life cycle consists of four main stages: egg, caterpillar (larva), pupa (chrysalis) and adult.

Caterpillars are central to your mission, but you may also see some eggs, pupae and adults, and it will be interesting to record them. This is why it is very useful to be able to recognize monarchs at each stage in their life cycle.


1,2 mm
0,9 mm
3 to 8 days
Description    Usually a single egg per milkweed plant, but sometimes several.

Creme-coloured or yellowish, oval and slightly conical, covered in longitudinal raised ridges.

Watch out for false eggs!
Milkweed produces a sticky whitish sap that sometimes forms small bubbles on the leaves. Be careful not to confuse these droplets with monarch eggs! To distinguish between them, look carefully (with a magnifying glass): a monarch egg is covered in vertical lines.

  • Small whitish bubbles, rather spherical.
  • Different sizes, may resemble a monarch egg.


2 to 45 mm
0.5 to 8 mm
0.6 to 2.2 mm
7 to 17 days
Appearence Yellow, black and white stripes

Black filaments near its head and at the tip of its abdomen (barely visible on young caterpillars)

White spots on false legs (older caterpillars)

Usually seen on milkweed plants,but older caterpillars move about looking for somewhere to pupate.

Behavior Young caterpillars feed on the leaf, making semi-circular holes, starting in the centre of the leaf. After a few days, they start to feed on leaf edges.


3 cm
1 cm
8 to 15 days
Description    Turquoise-green, with gold spots.

Gradually darkens until the adult colours show through the transparent case, about 24 to 48 hours before the butterfly emerges.

Excellent camouflage! Pupae are difficult to spot in the wild.

Often found elsewhere than on milkweed plants.


9 to 11 cm
3 to 5 weeks or about 8 months (migratory generation)
Description    Orange wings with black veins and white-spotted edges

Some of the largest butterflies in Canada

Males show circular black spots on their hind wings.

A few tips

Take the time to look closely

Monarchs are very good at hiding. Check every leaf (underneath and on top!), flower and fruit on the milkweed plant for eggs and caterpillars. You don’t want to miss anything!

Make sure you count the right thing!

Even the most experienced observers can make mistakes. It’s not always easy to recognize a monarch egg or to distinguish between the different larval instars! So take the time to look closely at the specimens you find, and don’t hesitate to take photos to confirm your identifications. Remember that other species of insects, as well as their caterpillars, also live on milkweed plants. Not everything you see is necessarily a monarch.

Ask for help

Questions? Feel free to consult the Help section of the website. And if you can’t find the answer there, contact us. We’ll be pleased to help you.

Main points

In the field, you will need:

  1. Pencils and a hard surface to write on, or any electronic device that can connect to the internet
  2. The form to be completed, in electronic or paper format
  3. Suntan lotion and a bottle of water – you may be out in the sun for a while!

You may also find these items useful on your expeditions:

  1. A magnifying glass
  2. Milkweed identification sheets and caterpillar identification sheets for the different larval instars.
  3. A notebook for observations and questions.
  4. A camera – take pictures of what you see! You can validate your observations and share them in the photo gallery on the website.

Remember to wear closed shoes and long pants.