The monarch egg in the above image is about 60 times taller than a real monarch egg. Note, too, the bullet shape, the cream color, and lines that radiate from the tip toward the base of the egg as if engraved by a jewler. The blunt base of this egg was affixed with a natural "glue" secreted by the female.
The bead of milkweed sap -- magnified in the picture -- was extruded from a leaf vein. Tiny droplets of milkweed sap sometimes mimic monarch eggs, but are globe-shaped and milky white, as in the picture. A small hand lens is a good tool for determining the difference.
Depending on the season and air temperature, monarch eggs in our locale require four to eight days
to hatch, closer to eight days if nights are cool. Because spiders and insect predators feed on monarch eggs, we generally remove an egg-bearing leaf -- after checking for potential predators -- to a safe, covered container. If a leaf wilts before the larva hatches, we place a small, fresh leaf next to it for the caterpillar to find and use.
If disturbed, even a freshly hatched monarch caterpillar may spin silk to secure itself. If it does, and winds up swinging from an almost invisible filament, it may perish if the filament breaks or is blown away.