Spider with parasitic wasp larva

Bruce Williams · #1 (**permalink**) 05-10-2009, 09:56 PM

Northants garden.

Well I'm assuming it's a parasitic wasp larva? Help with identification appreciated.

Bruce

ChrisR · #2 (**permalink**) 05-10-2009, 10:51 PM

Yes, that's an ichneumon larva - nice find!

I would guess that it is a species of Polysphincta - see here - a pimpline ichneumonid. I'd be happy to identify it for you if you can rear it through to the adult stage and get the specimen to me somehow. There are about 3 or 4 species in the UK and they need microscopic examination to key them out but I have all the necessary keys etc.

Rearing them isn't as difficult as it might seem - I did it twice and it was quite good fun. Basically just put the spider in a jar with ventilation (a paper lid held on with a rubber band or a cork bung will do), some sticks to climb over, and dry substrate on the bottom. Put in there a small water pot (an old drinks bottle cap will do) and then feed it with mosquitos or other small flies that you can catch in the garden.

The larva will continue to suck the blood or the spider but it will look like nothing is happening - it won't even grow much bigger. Then when it senses that the spider is big enough and fat enough to be worth eating it will (overnight) completely devour the spider and start to spin a cocoon in the spider's silken web. The wasp should then hatch out a few weeks later

Chris R.

Bruce Williams · #3 (**permalink**) 06-10-2009, 10:10 AM

Thanks for your help and info on the parasitic larva. It's unlikely that I'll be able to locate the spider again (large area of shrubbery) however if I do then I'll give your suggestion a try. It does sound interesting albeit a little gruesome - but then there's the added prosect of more photos.....

I would also appreciate an id on the spider if pos.

Bruce

ChrisR · #4 (**permalink**) 06-10-2009, 11:09 AM

Quote:

Originally Posted by Bruce Williams

Thanks for your help and info on the parasitic larva. It's unlikely that I'll be able to locate the spider again (large area of shrubbery) however if I do then I'll give your suggestion a try. It does sound interesting albeit a little gruesome - but then there's the added prosect of more photos.....

Absolutely - and if you do a Search on the Spider forum for 'parasite' then you'll see that several other members have posted similar photos - so these parasites are not that hard to find if you keep a good lookout

Chris R.

Jason Green · #5 (**permalink**) 06-10-2009, 12:21 PM

Afternoon Bruce,

I think I saw the same spider myself yesterday, in Battersea Park.

Recognise those spots? Pinched carapace, pale border...

...no parasite here, though! Seen on a Plane tree.

charlieb · #6 (**permalink**) 06-10-2009, 12:52 PM

Quote:

Originally Posted by ChrisR

it was quite good fun.

For you maybe...!

ChrisR · #7 (**permalink**) 06-10-2009, 01:29 PM

Quote:

Originally Posted by charlieb

For you maybe...!

For parasitologists there's just 2 types of wildlife: "interesting things" and "hosts"

Rambling Rob · #8 (**permalink**) 06-10-2009, 02:31 PM

Back in May I found a similar combo on an Iris leaf in the local park in Sandown...

Rob

Venger · #9 (**permalink**) 06-10-2009, 03:44 PM

It's an Araniella sp - they seem to be a favourite victim.
I've always founds them smaller when compared to others without the wasp larvae.

Bruce Williams · #10 (**permalink**) 06-10-2009, 08:07 PM

Jason - Thanks for posting your photo. I would agree with you that they look to be the same (or closely related) species.

Rob - Thanks for posting your pic. Apart from colour it looks very similar to the other two spiders.....and that's a big larva (or a small spider

).

Des - Thanks for help with id and passing on your experience re. effect of parasitic larva on host size.

Bruce