Saturday 12 June 2021

Welcome to the World, little Coleophora laricella!

Coleophora laricella - Larch Case-bearer, isn't massively common in Norfolk, with steady records but not exactly inundated. I walk past the same handful of young Larch trees quite often in the village but must admit to never having spent too much time looking hard for any signs of the larvae.

With that in mind, just over a month ago, in the first week of May, I made a concious effort to search properly and after a while I spotted the target. I don't rear larvae through as much as I used to, or indeed as much I'd like to but that's all down to time restraints and not something to do half-arsed, but I felt commited and wanted to see the adult of this one, so it came home with me to finish the larval stage of its life off in "Kerr Nurseries TM"...the outhouse toilet room.

I find the best way to keep foodplant fresh is to use a small tub, cut a block of oasis (and soak) to fill the inside, drill a hole in the lid (big enough to slot the stems of the plant into but no bigger) and place the whole thing in a small bucket with some tights/pop socks over the top so you can observe without disturbing too much. Add larvae and wait.

Rearing larvae through is a great way to watch and learn and as obvious as it might be to some, from this one I learnt:

- The tips of the Larch needles become pale as they're eaten from the inside by the larva. Something I knew to look for but wasn't obvious to me until I'd seen my own example. Now I've seen it, they stand out a mile!

- When ready to pupate, this one parked itself in tight to the base of a sprig, making it more secure and even harder to find - I thought it had escaped at first!

- Pupation took just about 4weeks from 'parking' to emergence. That was at the average outside temp, albeit in an outhouse.

- The adult Moth is stunning! Titchy and Grey to the eye but under magnification and with some flash to light it up, it's Grey turns to Silver and is speckled with a rainbow of colours.

Larva inside its homemade case

Close-up of larva feeding. Note it doesn't eat the surface, but eats inside the needle, leaving it pale   
Larva 'parked' at base of a sprig for security during pupation

freshly emerged adult Moth

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