04 Thursday Aug 2022
Posted in insects
A year ago I wrote about the moth larvae I’d found living inside Teasel seed heads (Inside a Teasel seed head, July 2021). This year, during my recent walks, I’ve noticed small parasitic wasps on many of the flowering Teasels I’ve seen. I haven’t been able to identify these wasps but it occurs to me that they may been seeking that same species of larvae I saw last year, prodding and poking with those fierce-looking ovipositors until they found a soft body in which to lay their eggs.
21 Saturday May 2022
Tags
Chalcidoidea, Eulophidae, gem-coloured wasps, parasitic wasp, parasitoid wasp, wasps on Oak leaves
Tiny specks of metallic green and red caught the light as the sun emerged from behind large fluffy clouds and touched the leaves of an Oak tree. But what were they? Even when I edged closer, I could barely make them out, so miniscule were they. Turns out these are parasitoid wasps belonging to the superfamily Chalcidoidea, and probably from the genus Eulophidae, but that’s as far as the experts online could go without microscopic examination of these startling creatures. An article on the Natural History Museum website begins: ‘Described as “gem-like inhabitants of the woodlands by most never seen nor dreamt of”, chalcidoids include some of the most beautiful insects on the planet’, and I think you can see why.
16 Tuesday Nov 2021
Posted in insects
Tags
British hoverflies, Epistrophe grossulariae larva, hoverfly larva, parasitic wasp, wasp parasitising hoverfly larva
During Sunday morning’s meander around Cosmeston, I watched this little drama play out on a fence post: the larva of one of the Syrphus* species of hoverfly was being injected with eggs by a parasitic wasp. The poor larva was bucking about, desperately trying to get rid of the intruder, but to no avail. The wasp’s ovipositor was firmly wedged into the hoverfly larva, pumping eggs into its body. The larva will be eaten from the inside by the wasp’s larvae when they hatch.
*My ID was wrong. When I recorded this find, I got the following message from national recorder Geoffrey Wilkinson: ‘This is a small 3rd-stage Epistrophe grossulariae – the rear breathing tube is longer than broad and is two-toned in colour (brown tipped, clear base). Although the colour pattern has yet to fully develop you can just see the fish-bone pattern of green and make out the black dorsal dashes.’
18 Monday May 2020
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.
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.
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.
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.
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!
29 Wednesday Apr 2020
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.
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.
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).
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.
One of the mystery wasps, sitting on the edge of the jar, as it was being released
25 Saturday Apr 2020
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.
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.
07 Sunday Jan 2018
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).
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.
earthstar 
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