Recognizing monarchs


The Monarch Mission 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.



Photo: André Sarrazin


Height 1.2 mm
Lenght 0.9 mm
Duration 3 à 8 jours



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.

Photo: André Sarrazin




Lenght 2 to 45 mm
Width 0.5 to 8 mm
Head 0,6 to 2.2 mm
Duration 7 to 17 days



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.


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.


Photo: André Sarrazin


Lenght 3 cm
Width 1 cm
Duration 8 to 15 days



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.



Photo: André Sarrazin


Wingspan 9 to 11 cm
Duration 3 à 5 semaine ou environ 8 mois (génération migratrice)



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.

Photo: André Sarrazin