Butterfly Wings - Preservation Techniques?

I found these beautiful Monarch wings on the dirt below my Mexican Sunflowers. It was interesting to observe that the wings were there only -- no body. I was sad to observe the apparent demise of this beautiful butterfly, and wondered who could have been the culprit. Jumping critters like grasshoppers and prayingmantis are in the area, could they have been a possible predator?

In any event, I would love to preserve these beautiful wings. Any advice or recommendations on the process??

Thanks, Snug

I've heard that some folks use clear acrylic spray. I've not tried that myself so can't vouch for how well it works. It would be interesting to find out how to preserve them for I, too, have come across wings and dead butterflies...and well, am known to pick some off the truck grills at work when the wing is still in good condition.

~ Cat