Thursday, June 6, 2013

Monarch Butterfly Eggs

 The Monarch butterflies are returning from their long spring migration which begins in Mexico.

The Monarchs that are arriving here now are the second or third generation from those that left Mexico a few months ago.

As soon as the females arrive they seek out milkweed plants and lay eggs, usually on the underside of the new plant leaves.

The eggs are tiny but beautiful with amazing detailed design as can be seen in the picture above.
 The eggs are tiny, only one millimeter high and half that wide, or about 1/32 of an inch wide.

The egg in this picture can just be seen at the tip of the middle leaf, where the little creamy white dot is.

The eggs in these pictures were laid this past Monday morning, and I took the pictures last evening, except for the picture of the butterfly, which I took last fall.
 Here is another egg on the underside of a different leaf.  On the small patches of Common Milkweed and Swamp Milkweed in my garden there were about 25 eggs that I found.  There were less plants than that.

What I find amazing and mysterious is how the female Monarch can distinguish the tiny milkweed plants from all the other native prairie plants in the garden.

Many of these little eggs will be parasitized by even smaller wasps, or the caterpillars parasitized by a local fly.  So, not many make it to become an adult butterfly.

The milkweed leaves look kind of smooth until a closer look is taken. Then they become fuzzy jungles of thick growths on the leaf surface. 

I cut the edge of the leaf off to get the camera in close here, where two eggs can be seen.  The one on the left is the one in the top picture of this blog post.  The eggs are 5/8 of an inch apart, or 16 mm.

Looked at very close like the top picture these eggs look similar to the giant eggs in the movie Alien.  It is not too hard to see that sci fi special effects people look to real nature for their ideas.

I will try to get pictures of the eggs hatching and post them soon.  It normally takes 3 to 4 days for the eggs to hatch, so sometime tonight or tomorow.


  1. Hi I was wondering if I could use one of you egg images for a conservation group newsletter?

  2. Hello Siah: I am a biologist/photographer and have completed a video on the Monarch Butterfly for use in the education of young people about metamorphosis in our local nature center. I am missing a photo of the monarch egg and wonder if I might use yours in my video. The video is strictly for education purposes and I will give you credit for your photo. Thank you. Lew Scharpf

    1. Hi Lew. Yes, you can use the photo. Good luck with the video. Siah

  3. Hi Siah, I am an Entomology graduate student at Ohio State and I'm looking for a Monarch egg photo to put in a 4-H project book about Entomology. Would it be possible for me to please use one of these photos to illustrate what native butterfly eggs look like? I would also give you photo credit. Thank you! Katie Todd (