Paralyzed Drumming Katydids found in Nest of a Grass Carrier Wasp

Subject: paralized grasshoppers in nest above my door?! Could they be victims or wasps?
Location: Andover, MA
July 2, 2012 7:53 pm
I opened my screen door and out drops dozens of small green grasshoppers (not sure what kind) onto my head!…
They are alive but not able to move very much. My guess is they were parasitized by a wasp. If this it true, I’m assuming wasp eggs were laid in these pretty little things.
I would love to know for sure!
Thanks BugMan!
Roberta
Signature: covered in grasshoppers

Paralyzed Drumming Katydid Nymph

Hi Roberta,
We will be writing to both Piotr Naskrecki and Eric Eaton to try to get to the bottom of this food chain mystery.  These are not Grasshoppers because their antennae are too long.  They are some immature Longhorned Orthopteran in the suborder Ensifera.  The specimen in hand appears to be a juvenile female because of the presence of an Ovipositor.  Perhaps Piotr who specializes in Katydids can provide species or genus information.  Thank you for including the nesting material.  It is most unusual and we do not know of a Parasitic Wasp that uses straw to build a nest, but perhaps Piotr or Eric will know more on that subject.

Paralyzed Drumming Katydid Nymphs with nesting material

Piotr Naskrecki identifies Katydids
Hi Daniel,
Cannot tell you much about who paralyzed these katydids (my guess would be a sphecid wasp of some kind), but the insects themselves are nymphs of Meconema thalassinum, a European species, introduced and now common in the Eastern US.
Cheers,
Piotr

Ed. Note:  BugGuide identifies Meconema thalassinumas the Drumming Katydid.

Cache of Katydids from Nest

Eric Eaton provides a likely Predator:  Grass Carrier Wasp
Hi Daniel, Piotr:
Very interesting!  The wasps building the straw nests would be “grass-carriers” in the genus Isodontia, family Sphecidae.  I think the host here would be a new record since the wasps are native but the prey is not.  There are at least three or four Isodontia spp. in Massachusetts, so without at least an image of the wasp we can’t make an association.
Eric

Update from Roberta:  Larvae Emerge
Hi Daniel,
Thanks for the response. Larvae have started emerging from the katydids.  I have attached a couple of photos.  I did the best I could without a macro lens.
I have wasps buzzing around my house with little pieces of straw in-hand.   So a wasp came to mind as the culprit when the katydids dropped on my head.
They are still on my deck;  I would like to put them out of their misery if that’s okay?
Thanks again!
Roberta

Wasp Larvae emerge and feed on Katydids

Ed. Note:  We missed Roberta’s first update and we added them to the original posting out of order.
Hi Roberta,
We somehow missed your first update.  While we understand the sympathy you feel for the Katydids, we can’t help but to marvel at the cache of Drumming Katydids that the Grass Carrying Wasp assembled and we hate to see that effort go to waste.  We wish you could provide a suitable substitute habitat and let nature take its course.

Update from Roberta:  Photo of the predator
Hi Daniel,
I attached a photo of the wasp .  I believe this is the species of wasp that is parasitizing the Drumming katydids.   There were a number of these wasps flying around carrying pieces of grass.  This one, however, isn’t.
I hope this helps.
Thanks!
Roberta

Grass Carrier Wasp

Hi Roberta,
We feel we are making a conviction based on circumstantial evidence, but we are nonetheless pleased to arrive at the same conclusion that you have:  that this Grass Carrier Wasp or one of its relatives built the grass nest that was provisioned with immature Drumming Katydids.  Thank you so much for the follow-up.  This is exactly the type of interactive posting we love, complete with expert testimony.  Additionally, through a continued effort on your part, you photographed the interconnectivity between these two species, the predator and the prey.  It should be noted that like other wasps that prey upon insects, it is done for the purpose of feeding a brood.  The adults feed on nectar, most likely because during the evolutionary process, parents that did not compete with their young for the same food supply produced more offspring since food did not have to be shared.

Hi Daniel,
The scientist in me decided to let nature take its course; I placed the katydids in a covered area of my yard.
I kept one of the katydids to follow the development of the Grass Carrying Wasp.
I will let you know if I am successful in raising the wasp to adulthood.
Thanks so much for your wonderful site.
Roberta

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