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Joe pupates

Joe Acronicta had had enough of us poking and prodding him, and decided to pupate.

I know that most Acronicta species pupate by tunneling into soft, dead wood. But usually this is a shallow groove, covered by bits of wood and silk. Sometimes they burrow in deeper, but you can see the hole behind them.

Joe decided to be a bit like some other Acronictines (species in different genera, but still closely related to Acronicta). Genera like Comachara, Polygrammate, and Harrisimemna all dig deep tunnels into wood. Then they crawl out and back into the tunnel rear-end first, sealing up the entrance with silk and bits of wood.

That’s exactly what Joe did.

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Joe, diligently digging his tunnel. blog_3

The pile of chewed wood left behind.blog_4

The cleverly disguised entrance.

I’m not sure how long it will be before he emerges, maybe a few weeks or months? When caterpillars pupate early in the season, it usually (but not always) means they will emerge in time to start another brood before cold weather arrives. If they pupate late in the season, they will usually (but not always) overwinter as a pupa.

While we are pretty sure that we have these caterpillars matched up with the correct adult, we are excited to have an adult emerge so we are 100% sure. I’ll post pictures when Joe makes his appearance as a moth!

Escaping the pupal shell

Life is getting more exciting here in the Wagner lab – moths are emerging! Every year we raise hundreds and hundreds of caterpillars for various projects. I am only directly involved in rearing my own specimens, but we have an army of undergraduates who help Dave rear caterpillars for his books and research. We have a “rearing room” in the lab where they are kept as caterpillars during the summer, and as pupae during the winter. Lately we have been increasing the photoperiod, heat, and humidity in order to encourage the moths to emerge a bit early. We are going to kill them to become specimens, and it’s nice to get all the pinning done before the field collecting season starts.

Today some lab members alerted me to this moth, a cute fuzzy species in the genus Cucullia (family Noctuidae). It had created its pupal chamber directly against the bottom of the plastic container amidst some paper towel. We thought this would make it easier for it to emerge, but it couldn’t seem to figure out what to do.

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Its head appeared to be stuck, and it could not manage to break apart any other section of the pupal shell. We were about to cut it open to help, when…

Hurray! It emerged! It had to do some interesting yoga moves to flip around, but it got out of there in the end. It then took a few minutes to inflate its wings with hemolymph, and after a short time started looking like a regular moth.

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Usually moths emerge at night in order to fluff up their wings out of sight of birds… so we had never seen a dramatic emergence such as this. Maybe it just needed some encouragement.

Ryerson Lab

Functional Morphology, Sensory Biology, Behavior, Biomechanics

I spell it nature

Trying to make sense of the world through science and language.