PacSci Perspectives


Fresh Sheet – June 3, 2017

by | Jun 3, 2017

T harmonia pupae

Sparkling pupae of Tithorea harmonia (Harmonia Tigerwing) soon to emerge in our Tropical Butterfly House.

Some butterfly pupae are interesting and lovely including two species we received this week that appear to be metallic, Mechanitis polymnia (Polymnia Tigerwing) and Tithorea harmonia (Harmonia Tigerwing). All Danaidae tribe butterflies, of which these two species belong, exhibit some “metallic” cells on their chrysalis. Of course, they are not metallic. The cuticle cells simply reflect light and give off a shiny appearance. This is due to the result of photonic crystals that are layered in the areas that reflect a narrow range of light waves. See this article from Cornell University for a technical explanation.

But as much as nanophysicists have learned about how the shiny exterior of these pupae are formed, they are not certain about how this feature benefits the butterfly. Here are some hypotheses:

a) They could reflect colors of the surroundings and act as camouflage.
b) Perhaps the pupae look like dew droplets.
c) The reflective surface could signal a warning of toxicity to predators.
d) Maybe the photonic crystals filter light that is harmful to the developing butterfly.
e) It’s possible the butterflies’ predators cannot see these parts of the spectrum.
f) They might not have any function, but just be the result of something else in the cuticle of the insect.

What other reasons can you think of?

Neotropical Insects NV

26 – Battus polydamas (Polydamus Swallowtail)
15 – Heraclides thoas (Thoas Swallowtail)
40 – Heraclides anchisiades (Ruby-spotted Swallowtail)
10 – Heliconius melpomene (Postman)
15 – Dryas iulia (Julia Longwing)
40 – Anartia amathea (Scarlet Peacock)
40 – Archeoprepona demophoon (Hubner’s Prepona)
9 – Biblis hyperia (Red Rim)
40 – Caligo memnon (Owl Butterfly)
10 – Eryphanis polyxena (Purple Mort Bleu Owl)
20 – Mechanitis polymnia (Polymnia Tigerwing)
35 – Tithorea harmonia (Harmonia Tigerwing)

Total = 300

“Fresh Sheet” is our weekly shipment report of pupae on display in the emerging window. Visit Pacific Science Center’s Tropical Butterfly House and meet our newest residents.

These butterflies typically arrive as pupae on the Thursday or Friday before the Fresh Sheet is published. Some of these butterflies will start emerging the day they arrive or the next day, but other species may take a full week before they reach adulthood. After emerging, they may live for a week or even a few months! While we love sharing a variety of species with our guests, we cannot guarantee that any specific species will be flying on the day that you visit Pacific Science Center.

If you are interested in photographing a specific butterfly and would like to be updated about when it is flying in the Tropical Butterfly House, please email with details and your contact information.