Mystery of the moth scales!

Oct 22, 2017 • 11:13 AM UTC

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Mitali

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Happy Diwali Everyone,

Moths are pretty rare here in Mumbai. This little guy flew in my window a few days a ago and landed directly on my arm. I have wanted to observe butterfly or moth scales since a very long time and I didn’t want this guy to flee before I could observe it’s scales.
Very carefully, I caught the moth in a zip lock bag.Thankfully it wasn’t fast enough to fly away. Then I took a paper slide and put the cello tape on it. Then, with the help of forceps i gently just touched the moth wings with the sticky side of the tape.
The scales come off very easily and a gentle touch to the wings is enough to get us a lot of scales on the slide.
You can do it without catching the moth or butterfly in the bag.I’m attaching a video to show how you can try it out

I’ve observed scales from 2 regions in the moth – The thorax had a mixture of many types of scale and the actual wings showed 2 types.
What was truly amazing was that some scales appeared different in dark field
Sharing pics of the scales on the wings first,

the first type of scales (Bright field)

The same type in Dark field.
some more pics,

Something interesting I found while observing the slide today was that these scales appeared blue-violet on angular illumination.

I tried illuminating from different directions, but it didn’t produce any color other than blue. They appear like this on angular illumination from a different direction.

This reminds me of the structural pigment in Morpho didius. I’ve been reading about those since I started observing these moth scales.
The other type scales on the wings

This is a dark field image of the 2nd type of scales, as we can see they appear very different. They seen to not have the grooves we observe in the larger scales

In these pictures we can clearly see the difference in both the types of scales.
I will do a detailed post on the types of scales on the dorsal thorax region as well. Please do share your opinions on this post and suggest some good reads about the nano structures of the scales.
~Have Fun Foldscoping.
– Mitali Patil
Second Year Undergraduate
Ramnarain Ruia College, Mumbai.