A monarch egg is very tiny: just 1.2 mm high and 0.9 mm across at its widest point. It is slightly conical, with a creamy yellow surface and fine ridges running from the tip to the base.
To lay them all!
In the wild, a female monarch lays between 300 and 400 eggs. She glues them one at a time to the underside of milkweed leaves. That way, the young caterpillars have access to their food as soon as they hatch.
How long the eggs take to incubate depends on temperatures: the warmer it is, the faster they hatch. On average, eggs hatch 3 to 5 days after they are laid.
A female monarch in captivity can lay as many as 700 eggs in 2 to 5 weeks!