…When I found a bright lime green caterpillar as big as my third finger chugging across a path in our yard.
I immediately pulled out the iNaturalist app, which helpfully identified it as the caterpillar of a Polyphemus moth. And wow, what a moth it is! It belongs to a family of giant silk moths (Saturniidae) and has an average wingspan of 6 inches (15 cm).
Photo © Stephen Lody Photography, CC BY-SA 3.0
Wikipedia’s entry tells me that the Antheraea polyphemus caterpillar can eat a total of 86,000 times its weight, from a wide variety of plants, in the first eight weeks after it emerges. They moult 5 times; the one I found was in its last stage before becoming a pupa and spinning its silky cocoon. (Adult moths do not eat and live as adults for less than one week.)
After our photo op I set the caterpillar back where I found it, and when last seen it was heading up into the ornamental plum tree. Possibly hard on the plum tree, but worth it if it produces such a gem.
Three fun facts about Polyphemus moths
- I don’t know about the other stages, but the final-stage caterpillar has a retractable head, like a turtle.
- You can tell which sex one of these moths is by looking at their antennae. Males have very bushy antennae. Females have tubbier bodies, because they carry eggs.
- The “eyespots” on the wings are a defense mechanism that helps protect adult moths from predators. The caterpillars defend themselves by producing clicking sounds from their serrated mandibles when they are gently prodded, and then regurgitate. (I wish I’d known this at the time! But perhaps it’s better that I didn’t.)
All photos © Nola Johnston, used with permission, except the one attributed to Stephen Lody Photography
Also found on Gabriola
Some years ago I was fortunate enough to find and hatch the cocoon of a Ceanothus silkmoth (Hyalophora euryalus, also in the Saturniidae family), and spending an hour and a half watching it gently stretch its new wings and then shiver them to warm up its flight muscles was something I’ll never forget. Giant silk moths are absolutely amazing. I hope you are lucky enough to encounter one.
