Help, this pupa had multiplied?

[Cappi]

We found a caterpillar in the house on the 4th December and decided to look after it. We thought it was an Angle Shades. Can anyone confirm this?



It happily ate a variety of fruit tree leaves at night and then stopped eating. It then changed colour and became sticky around the 15th December. A few days later it had pupated.



A few days ago we noticed four brown egg like shapes around the pupa and it looked like they had emerged and trailed away. There was also a yellow substance next to the pupa with the four trails leading away from it, as seen in the picture.



Can someone please tell me what has happened to the pupa and what i should do with it?

[Dogghound]

What has happened is your pupa has been the host of a parasitic fly (Diptera), Tachnidae. These have hatched out and pupated. Very common in the insect world. Yes the caterpillar is an angle shades.

[Cappi]

Thank you for your answer. I have a couple more questions as i'm intrigued.

Is the pupa dead now, or will it still go on to become a moth? Also, at what stage would the fly had infected the pupa? Have i been looking after an already infected caterpillar since i found it? I'm undecided on what to do with it now.

[Dogghound]

The pupa is now dead yes. The caterpillar will have been carrying the eggs before it turned into a pupa, these will have fed on its insides then emerged in the night and pupated. If you dont want to view the flies I would advise you put them in a dry sheltered location outside, possibly amoungst leaflitter or deep in a tussock or amoungst brambles, its all part of nature, these in turn will provide food for birds, spiders etc.

[Cappi]

Thank you for your answer yet again. I've heard about the parasites, but never knew the process and it's interesting seeing it in real life.

It's a shame on not seeing through the process of caterpillar to moth, but such is the reality of nature. Thanks again.

[Lance Morgan]

The caterpillar was the green form of the Angleshades moth by the way

[Dogghound]

Better look with hatching a moth next year. All the best....

[Wild-Woman]

I think I'd want to know exactly what fly had parasitised the caterpillar. You never know- something may have parasitised them too!!

[Torymus]

Keep the puparia of the tachinid - somewhere cool, perhaps the shed and don't forget to look at them now and again. Get the fly identified. Less is known about tachinid flies than the moth itself.

[ChrisR]

I have just found this thread ...

I agree with all that has been said so far - tachinids are fascinating parasitoids and it would be very interesting to know which species attacked the Angle Shades If you keep the pupae, as described, and some flies hatch out then get in touch and I can identify them for you. The group is very difficult for novices to identify reliably but I run the UK recording scheme (http://tachinidae.org.uk/) so I have all the necessary keys