The life story of the monarch: The egg

More than just the adult butterfly stage!

Looking a bit worn  ©Janet Allen
Arriving in CNY, looking a bit worn

The first amazing thing about monarchs is that they arrive here in Central New York at all. After all, they have never been here before! The overwintering generation leaves Mexico and lays eggs in US states north of Mexico, and these become adults around late April and May.

It is these adults that completes the journey to the northernmost reaches of their breeding grounds, reaching here mid- to late-June. (Sometimes the media says it takes four generations, but that's not accurate. Check MonarchWatch …)


These are the dates of our first sightings in our yard:

  • 2007: June 23
  • 2008: June 22
  • 2009: June 26
  • 2010: June 24
  • 2011: June 16
  • 2012: May 20 - very early with an early spring
  • 2013: July 18 - very late; saw only 4 all summer and no eggs!
  • 2014: July 10 - late, and found 7 eggs over the summer
  • 2015: July 5 - didn't see the adult, but we found one egg
Monarchs mating ©Janet AllenMonarchs mating

No matter how many times we've watched this whole process with hundreds of eggs, caterpillars, and finally the adult butterflies, it remains fascinating.

It was amazing to see these two mating. They flew around the yard for hours, the female dangling from the male. The male is the top one.

Monarch scent gland ©Janet AllenThe male monarch's scent gland

How did I know the male was the one on the top? I saw the scent gland—the small black raised bump in the middle of the photo. It's an easy way to tell the male from the female.

Another clue is that the female has wider, darker veins on her wings.

Monarch laying egg ©Janet AllenMonarch laying egg

This monarch is laying an egg on a swamp milkweed leaf.

Once hatched, the monarch caterpillar can eat ONLY milkweed, so we grow lots of milkweed plants.

Lack of milkweed in the monarch breeding areas is one of the primary reasons for the decline of the monarch butterfly.

monarch egg ©Janet AllenA monarch egg on a common milkweed leaf

When we first started looking for monarch eggs, it was confusing. We didn't know how big the eggs were, and milkweeds often have little spots of latex (the "milk" that look like eggs.

After a while, though, these ridged, ivory-colored, oval-shaped eggs seem very distinctive and easy to distinguish from the pure white, rounder drops of latex.

Small milkweed ©Janet AllenTiny milkweed

We were surprised to see a monarch laying an egg on this very small milkweed plant. I put bricks around the plant to protect it.

I soon discovered that it wasn't unusual at all, at least in my yard. Perhaps they prefer the tender leaves of this young plant and assume that the plant will grow faster than the caterpillar can eat it.

Since this was the only milkweed within a baby catepillar's traveling distance, though, it seems a risky strategy. In the past, monarchs would have been laying eggs in large patches of milkweed in fields.

Monarch egg  ©Janet Allen
Monarch egg, with a penny for scale

After just a few days, the top becomes black. This will be the future caterpillar's glossy black head. This egg will soon hatch!