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Some of you may remember I found two Orange-tip pupae last summer at Bookham, one green and one brown. Both had chosen to pupate on their last meal but since they were on the very edge of a lane, I took them both home, fearing they wouldn’t survive the winter due to passing cars, horses, walkers, cyclists etc. Here they are in situ last year: Anyway I left removing them from my fridge as late as I thought I could get away with in the hope I’d be able to return them from whence they came as travel restrictions were eased. I was a bit lax with photos straight away but after a couple of days I noticed the green one had started to turn brown. Two days later the brown patches had become a lot more extensive, something fishy was definitely going on. The next day the brown one had also changed to a slightly more orangey hue And they day after that the colours were most definitely off. For one reason or another I didn’t check them the next day (stupidly), but the day after my worst fears were realised, something had emerged from both, but it wasn’t the springtime beauty we all look forward too. Annoyingly whatever had emerged had buggered off. A few days later I took them out with me to get some better pictures of the grotesque scene in natural light. Nature comes in many forms

Great observations Paul

I had a similar experience recently with a green pupa, but I had it in a pot after it had gone brown, so was able to contain and find the culprit. It turned out to be a parasitic Tachinid fly. The grub emerges from the pupa and descends to the ground down a mucus "rope" which it secretes. It then finds a safe location to pupate and the adult fly emerges after a few weeks.
This is a staged shot, because the fly puparium is usually found further away from the host.

Another staged shot shows the adult fly having emerged from a Small White pupa.
The fly was identified by Chris Raper at the Natural History Museum.

Vince

Thanks for the info Vince, the strand did indeed look like dried mucus . I must admit I was a bit casual with these and never got round to putting them in an emergence cage. If a large Tachnid fly suddenly appears in my front room I'll know where it came from. I'm not massively surprised to find it was a Tachnid, they seem to be particularly numerous at Bookham in high summer.

Thanks for the images, Paul. Such a shame that parasites got to them. It just shows how vulnerable all stages of butterflies' life-cycles are.

bugboy wrote: ↑Wed Apr 21, 2021 9:11 pm Some of you may remember I found two Orange-tip pupae last summer at Bookham, one green and one brown. Both had chosen to pupate on their last meal but since they were on the very edge of a lane, I took them both home,

Really well spotted to find the pupae in the first place. It was interesting to find out how parasites overwinter. Apparently, the United kingdom has about 270 species of tachinid fly.
Just an err of caution, to someone wanting to take a pupa home.
Some butterfly species were flighty, even migratory, when they didn't carry life cycle ending parasites, in that stage of their life cycle. That could have taken them outside of an area where parasites were common. Someone might have needed to be careful, one didn't want a non native, invasive species, extending it's range, by someone naively transporting it.
I wasn't specifically sure what Her Majesty's Laws were regarding this, so catching me taking wild fauna, might now be on someones bucket list
To an untrained eye, caterpillars didn't have, like a label on them, reading "Parasite inside"
Kind Regards,

Philip

Sadly, the same thing happened to Shvetaketu last year, except much faster. He pupated on 12th June and was dead a week later. This photo was taken on 20th June:



Some will remember a thrips larva that had been on him just after pupation:



I had put the demise down to this inadvertently puncturing Shvetaketu and his contents leaking. Judging by this thread, it looks as if something else was to blame.

Guy

Interesting that yours emerged in the same season Guy, whereas mine hibernated (in my fridge). I found mine in July so there must have been plenty of time to develop. perhaps different species?

A couple of days ago two flies appeared on the inside of my front room window, looking suspiciously spiny and Tachinid-like. It would seem this is what spent the winter in my fridge and emerged from my Orange-tip pupae .

Hi Paul, my fly emerged yesterday.
I will be sending it off to the Natural History Museum for identification soon, but it's likely to be either Phryxe vulgaris or Phryxe nemea.

On a new point of interest, I've just noticed a small suspicious-looking spherical cocoon on one of the pupae, possibly belonging to a parasitic wasp?

Vince

Gruesome as it is, this thread has been extremely educational for me. My eyes have been as big as saucers reading it. I had no idea this sort of thing went on. I liked that brilliant, succinct, eerie and sinister ending at the start - 'Nature comes in many forms'. It is like a trailer for a film, if you say it in a certain voice.

It's a dark and murky world to get sucked into Otep, there's all sorts of gruesome things happening right under our noses. Some of the smallest complete their entire lifecycle inside a butterflies egg and then there's parasitoids of parasitoids: imagine the thing eating your insides is itself being eaten by something else from the inside out...

For those that are interested, I have just updated my Orange-tip species report to include a more detailed account of the parasitic event I observed.
https://ukbutterflies.co.uk/phpBB/viewt ... =20#p69877

Vince