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Tag Archives: parasitic wasp

139/366 A tale of two galls

18 Monday May 2020

Posted by sconzani in insects, nature

≈ 3 Comments

Tags

Bedeguar gall wasp, British wasps, Diplolepis rosae, Orthopelma mediator, parasite of Bedeguar gall wasp, parasite of Diplolepis rosae, parasitic wasp, Robin's pincushion

This is a tale of two galls. One gall (below, left) was created by the Thistle gall fly (Urophora cardui), the other (below, right) by the Bedeguar gall wasp (Diplolepis rosae). I harvested the first gall late last year, the second early this year and, when I brought that second gall home, I made a rookie error – I put it in the same jar as the first gall. Why was that an error? Because it meant that if/when anything emerged from the galls, I wouldn’t know which gall it came from.

200429 2 thistle gall fly gall
200516 diplolepis rosae gall (2)

A few weeks ago, in late April, creatures began emerging from one or other or both of the galls. At the time, because I found an empty pupa case poking out of a hole in the Thistle gall, I assumed the creatures had emerged from it – I wrote about that in What’s in a gall?, April 2020. It turns out I was wrong.

200518 3 bedeguar gall wasp and orthopelma mediator

After writing that piece, I decided to place the galls in two separate jars and, as I wrote in a post last week, two different wasp species have subsequently emerged from the Bedeguar gall wasp’s gall, the gall causer itself (Diplolepis rosae) (above, left) and a second wasp (above, right), which turns out to be the same species of wasp I wrote about in April and which, at the time, I thought had emerged from the Thistle gall fly’s gall.

200518 4 Orthopelma mediator

The empty pupa case is now a mystery but the second wasp’s identity has been confirmed as Orthopelma mediator, a parasite of the Bedeguar gall wasp. So, adding to the initial three that emerged, a total of four of these wasps have now hatched from that gall. Amazingly, there is only one previous record, from 1933, for this wasp in the Welsh records database but I don’t think that’s because it’s a rare find; it’s just that no one bothers to keep the galls to see what emerges from them and thus the wasp is under-recorded.

200518 5 Orthopelma mediator

So, I hope I have convinced you that this is a fascinating process which you might also like to try but do remember the moral of this tale of two galls: if you decide to bring home galls to see what might hatch out, make sure you put each and every gall in a separate jar!

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120/366 What’s in a gall?

29 Wednesday Apr 2020

Posted by sconzani in insects, nature

≈ 3 Comments

Tags

British galls, British wasps, parasite of Urophora cardui, parasitic wasp, Thistle gall fly, Thistle gall fly gall, Urophora cardui

Back in October 2017, I blogged about a gall I’d found (More galls, part 2), the gall created by the Thistle gall fly (Urophora cardui). Here are two photos of those galls: on the left, the gall growing on the thistle (in fact, there are two galls – there’s a second one, still quite small, in the background to the left) and, on the right, a dried version, which I harvested from a thistle plant at the end of last year and which I’ve since been keeping at home in a jar.

200429 1 thistle gall fly gall
200429 2 thistle gall fly gall

According to my research, the Thistle gall flies don’t usually emerge until June but last week flying creatures began emerging from the gall. On closer examination, I found the empty pupae case (pictured below right) poking out of one of several holes in the gall.

200429 3 thistle gall fly gall
200429 4 thistle gall fly gall parasite

So far, five little critters have hatched but these are not Thistle gall flies. They appear to be some kind of parasitic wasp, which I have not yet managed to identify – there are thousands of species of parasitic wasp and these are not the species that is normally considered the primary parasite of the Urophora cardui (which is a wasp called Eurytoma robusta).

200429 5 thistle gall fly gall parasite

Underside of wasp, photographed through glass of jar

I don’t know whether any Thistle gall fly larvae or pupae still survive within the gall or, indeed, whether anything else will yet emerge. So, for now, the gall remains in its jar, and I’ll post again if any other aliens appear.

This story has a sequel as all in this gall was not as it seemed – here’s a link to part 2, A Tale of two galls, May 2020.

200429 6 thistle gall fly gall parasite

One of the mystery wasps, sitting on the edge of the jar, as it was being released

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116/366 A gall and its parasites

25 Saturday Apr 2020

Posted by sconzani in insects, nature, trees

≈ 6 Comments

Tags

Chalcis wasp, Oak apple gall, Oak apples, oak galls, oak tree, parasitic wasp, Torymidae

This must be the largest Oak apple gall I’ve ever seen – it was at least 1½ inches across, and it had attracted the interest of several small wasps, though these are not the wasps that created the gall in the first place.

200425 oak apple gall

I assumed that they were parasitic wasps about to use their long ovipositors to inject their own eggs into the gall, and it turns out my assumption was correct. Thanks to the British Plant Galls account on Twitter (@BritGalls), and to another Twitter user’s tweet, I’ve learnt that the tiny wasp in the photo below is a member of the Chalcis genus of wasps, probably one of the family of Torymidae. They are ectoparasites: their larvae feed on the larvae of the Oak apple gall wasp that created the gall in the first place.

200425 parasitic wasp

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Encyrtidae, a parasitic wasp

07 Sunday Jan 2018

Posted by sconzani in insects, nature

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Tags

Cosmeston, Cosmeston Lakes Country Park, Encyrtidae, insect parasites, parasitic wasp, wasp

Just when I was thinking the wee flying critters had probably all disappeared for winter, up pops this little chap, tootling around on the top of an old fence post that I was checking out for lichen. I’m reliably informed, by experts on a couple of specialist pages on Facebook, that this is a member of the Encyrtidae, one of a large family of over 3700 different parasitic wasps (and that’s just the ones that have so far been identified – there are probably many many more).

180107 Encyrtidae parasitic wasp (1)

Information on the Natural History Museum website states that ‘About half of the species of Encyrtidae are associated with scale-insects … generally as endoparasitoids of immatures or less commonly adults’, which means the wasp’s larvae live inside and eat the larvae, and occasionally the adults, of scale-insects – not a particularly nice way to survive, I have to say. Some of these wasps are also parasitic on the larvae of moths and butterflies – also not nice. Still, the wasp itself is a pretty little thing, and some Encyrtidae species have been used as biological control agents to control insect pests, so the news isn’t all bad.

180107 Encyrtidae parasitic wasp (2)

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About me

sconzani

sconzani

I'm a writer and photographer; researcher and blogger; birder and nature lover; countryside rambler and city strider; volunteer and biodiversity recorder.

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