I remember seeing my first Cyanothus silk moth (Hyalophora euryalus) on my front door a few years back. It was close enough to the ground that our idiot dog may gotten curious and accidentally done it some harm, so I moved it to a nearby tree. Once I got it onto my warm hand it began gently flexing its fore- and hindwings in a circular motion. I didn’t know it at the time, but what it was doing was warming up its wing muscles in preparation for flight. Since they’re such heavy moths they can’t just leap into the air like many geometrids or micromoths; they need to do a little calisthenics first. The larger the moth, the more the work.

The video below shows this behaviour in of another member in that genus, the Glover’s silkmoth (Hyalophora gloveri). Taken in May, 2023 up in Fort St John.

Tricks with light traps

This is common behaviour with the larger-bodied moth families. When I check the moth traps over the summer months I always try to get to the nets in the morning before it gets too hot – especially before the morning sun hits! – otherwise they’re already active and can’t be photographed. I find this to be a limiting factor in how many nets you can realistically set up. I typically set up four, but on warmer days you have to rush to get through them all. A few times I’ve gotten to the nets too late or placed them poorly so the morning sun hits them too early, and then you lose some of your catch.

Ideally you want to arrive when it’s still nice and cool (which inevitably means cutting short your sleep). It also helps to avoid touching them altogether where they use the warmth of your hand. Using materials like egg cartons in your nets is ideal: you can extract them en masse from the net without touching the moth, and then photograph them in place. When I found this technique I was able to take more photos of certain moth which would previously get spooked and take off before I could snap a shot.

Related:

• see notes on light traps here.
• see Saturniidae summary here.