Variations on a Theme: Egg Colors

The eggs of the Polydamas Swallowtail (Battus polydamas) are often easy to spot on on Pipevines as they are generally a golden yellow color, sometimes with hints of green and sometimes with a touch of orange. Today while checking for eggs on the Pipevines, I found these green specimens.

These eggs are sap green with barely a hint of the yellow-gold color we usually associate with this species. They were beautifully camouflaged in their surroundings and difficult to spot.

A Possible Advantage:

I have seen eggs of this color a few times over the past several months, but they are becoming increasingly more common in the BioWorks Butterfly Gardens. Perhaps this color variation is advantageous to the individual caterpillars that emerge from these eggs. It could be that they are afforded greater protection by the additional camouflage and that fewer of these green eggs are being spotted and consumed by predators. If the color of these eggs is in some way influenced by the genetics of these particular butterflies, it may be that more of them are surviving and passing this gene for color variation onto their offspring.

Side By Side:

While traveling the garden this morning I also found some of the golden yellow Polydamas eggs that we are used to seeing and I snapped a photo of the two colors of eggs side by side. These two color variations of eggs were found about 15 meters apart.

Color variation is common in the insect world. The dark form of the female Tiger Swallowtail is often seen in an overlapping range with the more recognizable light form of Tiger Swallowtail.

Click here for a National Geographic article entitled: Evolution in Color: From Peppered Moths to Walking Sticks

Click here to read more about the color differences between Polydamas and Pipevine Swallowtails.

Click here to read more about color variations in chrysalids.