Paula Lightfoot's picture

Parasitised caterpillar - Euplectrus bicolor?

Observed: 12th May 2011 By: Paula Lightfoot
Yorkshire Naturalists' Union
Paula Lightfoot’s reputation in InvertebratesPaula Lightfoot’s reputation in InvertebratesPaula Lightfoot’s reputation in Invertebrates
caterpillar 2
caterpillar 2 1
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Description:

I found this brown caterpillar alive on a chive stem, with what look like white grubs attached to its side.
Day 2: caterpillar dead, grubs spread out all over the body.
Day 3-4: white lacy cocoons formed
Day 5: black waste products (?) ejected. New photos uploaded.
Day 16: adults emerged! New photos uploaded.

Identifications
Species interactions

No interactions present.

Comments

DavidNotton's picture

HI Paula

Looks interesting, definitely some sort of parasitic wasp. Suggest you keep them and see what they turn into, and then post some more pictures.

Paula Lightfoot's picture

Thank you!

Thank you very much for the advice! Now the grubs have spread out all over the caterpillar's body and have started to produce white silk threads. I will keep watching...

DavidNotton's picture

Silk

Have they made cocoons now?

Paula Lightfoot's picture

fine 'lacy' cocoons

They haven't made solid papery cocoons, just a fine network of threads like a cage surrounding them and the caterpillar. It looks fuzzy, like fungal hyphae. Very similar to the photos of Euplectrus cocoons on the NHM website. How long is the pupal stage in Eulophidae species, or does it vary a lot between species?
Thanks, Paula

DavidNotton's picture

Euplectrus

sounds very likely. There is one certain British species E. bicolor, although best to rear it to be sure. You may be interested to see similar larvae on ispot, the host named as a double square-spot: http://www.ispot.org.uk/node/35184?nav=search. I don't know the life cycle of E. bicolor in detail, but I suspect at this time of the year they would emerge pretty soon, several weeks maybe, because there is time for another generation. Some other eulophids can be excluded at this stage such as Eulophus spp. because they don't make silk like this e.g.:
http://www.ispot.org.uk/node/105583?nav=search