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Tag Archives: galls

Holm oak gall mites

09 Wednesday Feb 2022

Posted by sconzani in insects, trees

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Aceria ilicis, British galls, gall mites, galls, galls on oak trees, Holm oak, mite galls, mite galls on Holm oak

During yesterday’s walk, when checking for leaf mines on the leaves of Holm oak (large numbers of Ectoedemia heringella present – you can see one in the photo below), I noticed a huge abundance of small bumps covering many of the leaves.

220209 Aceria ilicis on holm oak (1)

These are the galls caused by the miniscule mite Aceria ilicis. On the underside (though sometimes also on top), the depression in the leaf is filled with tiny brown hairs (an erineum) where the mites make their home. The galls can be seen throughout the year, so next time you spot a Holm oak, check out its leaves.

220209 Aceria ilicis on holm oak (2)
220209 Aceria ilicis on holm oak (3)

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Dasineura fraxini galls

03 Wednesday Nov 2021

Posted by sconzani in insects, leaves, trees

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Ash tree galls, Dasineura fraxini, gall causing midge, gall midges, galls, galls made by midges, galls on Ash leaves, midge gall

One of the benefits of checking the leaves of various trees, and other plants, for leafmines is that, even when I don’t find them, I do find other things just as interesting, and this is one of those. I didn’t know what it was, of course, until I got home and checked my Field Studies Council Guide to plant galls in Britain fold-out guide. (If you’re not familiar with these, check the FSC online shop here. I have a few of these and find them really useful.)

211103 Dasineura fraxini (1)
211103 Dasineura fraxini (2)

My guide informed me that these galls on the leaves of Ash trees were created by the larvae of Dasineura fraxini, a species of tiny midge. Few people have ever seen the adult midge but I did have a look at one of the galls that was partly open and spotted one of the miniscule orange larvae. These galls can be found from May through to October, at which time the leaves will fall to the ground, where the larvae will pupate and over-winter until emerging as adult midges in the springtime.

211103 Dasineura fraxini (3)

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302/366 Gone galling, again

28 Wednesday Oct 2020

Posted by sconzani in autumn, insects, leaves, trees

≈ 1 Comment

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Aceria macrochela, gall mites, gall-causing mites, galls, galls on Field maple, galls on Spindle, mite galls, Stenacis euonymi

October is a good month to check out life on leaves (and I’ll be writing some posts about the various leaf mines I’ve been finding) but today I want to show you a couple of gall species that are new to me. The first is quite common and easy to find, the second perhaps less so.

The first species is Aceria macrochela, a microscopic mite that spends its larval life in these tiny bumps on the leaves of Field maple (Acer campestre). You can read more about them and see more images on the mighty Nature Spot website.

201028 Aceria macrochela (1)
201028 Aceria macrochela (2)
201028 Aceria macrochela (3)
201028 Aceria macrochela (4)

And the second is also a mite, this one called Stenacis euonymi, whose larvae make their homes in the rolled-up edges of leaves on Spindle (Euonymus europaeus). If you have trouble with tree identification, as I often do, this is a good time to look for these as the gloriously obvious fruit of the Spindle are easy to spot.

201028 Stenacis euonymi (1)

Looking on the NBN (Nature Biodiversity Network) Atlas I see there are currently only 112 UK records for this species (113 including mine, which doesn’t show yet) but that’s probably due to it being under-recorded, so if you spot these, please do record your sighting.

201028 Stenacis euonymi (2)
201028 Stenacis euonymi (3)

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174/366 Mitey galls

22 Monday Jun 2020

Posted by sconzani in insects, leaves, nature, trees

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Aceria campestricola, Aceria ulmicola, gall mites, galls, galls on elm, leaf galls

When walking along a narrow path between fields last week, I turned to face into the neighbouring hedgerow so that two other walkers could safely pass behind me. In so doing, I noticed these galls, which I think are Aceria campestricola (also known as Aceria ulmicola).

These growths betray the presence of the hundreds, perhaps thousands of the tiny mites that have caused these galls to form.

These particular galls can only be found on specific elm species, which in Britain include English elm and Small-leaved elm.

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137/366 Bedeguar gall wasp

16 Saturday May 2020

Posted by sconzani in insects, nature

≈ 7 Comments

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Bedeguar gall wasp, British galls, British wasps, Diplolepis rosae, gall on dog-rose, gall wasps, galls, Robin's pincushion

You might remember that, a few months ago, I posted about the (supposedly) empty galls of the Bedeguar gall wasp I’d found during a wet walk at Cosmeston Lakes Country Park (Empty pincushions, January 2020). A week or so after writing that post, I was back at Cosmeston and remembered to harvest one of the galls, which has ever since been sitting in a sealed jar on my kitchen windowsill.

200516 diplolepis rosae gall (1)
200516 diplolepis rosae gall (2)
200516 diplolepis rosae gall (3)

Although the many holes in the gall made me think that all of its inhabitants had already hatched, I decided to wait and see if anything else appeared. Two days ago I noticed movement in the jar and, taking a closer look, found two different species of wasp had emerged.

200516 diplolepis rosae (1)

This is one of them, and I’m 99% certain this is the gall causer itself, the Bedeguar gall wasp, Diplolepis rosae, the offspring of the wasp that caused the gall to form in the first place. These wasps are so tiny – just 3-4 mm long – that most of us don’t usually see them so I was very pleased to have this one emerge from its gall.

200516 diplolepis rosae (2)

There is a bit of a story attached to the second wasp that emerged, and I am currently awaiting confirmation of its identity. As soon as I know more, I’ll write it up in a further post.

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31/366 Empty pincushions

31 Friday Jan 2020

Posted by sconzani in insects, nature, plants

≈ 5 Comments

Tags

Bedeguar gall wasp, British galls, Diplolepis rosae, gall on dog-rose, gall wasps, galls, Robin's pincushion

Robin’s pincushions are the amazing gall structures created on Dog roses by the larvae of Diplolepis rosae, the Bedeguar gall wasp.

200131 Robins pincushions (1)

I’ve seen the bright red galls many times during the summer months but I’ve not looked for them in the winter, so it was interesting today to find these and to see the very obvious holes where the adult wasps have hatched out. If it hadn’t been raining, I would have broken one off and brought it home for a closer look inside … maybe next week.

200131 Robins pincushions (2)

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252/365 Alder tongue

09 Monday Sep 2019

Posted by sconzani in 365DaysWildin2019, fungi, nature, trees

≈ 2 Comments

Tags

Alder, Alder tongue, British galls, Fungus-induced galls, galls, galls on Alder, Taphrina alni

While sneaking up on a juvenile Green woodpecker at Cosmeston, I spotted these lovely examples of Alder tongue (Taphrina alni).

190909 alder tongue (1)

I’ve covered these intriguing galls in a previous blog post so, just briefly, they’re the result of a fungus that chemically alters its host. One of Nature’s oddities!

190909 alder tongue (2)

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226/365 Robin’s pincushion

14 Wednesday Aug 2019

Posted by sconzani in insects, nature, plants

≈ 4 Comments

Tags

Bedeguar wasp gall, Diplolepis rosae, Dog-rose gall, gall on dog-rose, gall wasps, galls, Robin's pincushion

190814 robin's pincushion

Commonly known as Robin’s pincushion and found growing on Dog roses, this is a gall, the spectacular creation of a group of larvae of the Bedeguar gall wasp (Diplolepis rosae).

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155/365 A good crop of apples

04 Tuesday Jun 2019

Posted by sconzani in 365DaysWildin2019, insects, nature, trees

≈ 2 Comments

Tags

Biorhiza pallida, gall wasps, galls, galls on oak trees, Oak apples, oak galls, Pedunculate Oak

190604 oak apples (1)

But you wouldn’t want to eat them! These are oak apples, the incredible creations of the larvae of the wasp Biorhiza pallida. By a magical process of chemical interaction, the larvae force the buds of the Pedunculate Oak to change and produce these galls, which the larvae call home until they’re ready to develop into their next stage of life.

190604 oak apples (2)
190604 oak apples (3)

A couple of the young oak trees in some fields near where I live are proving particularly attractive to these wasps so they have a bounty of apples growing on them this year. Yet another of Nature’s miracles!

190604 oak apples (4)

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Andricus kollari, maybe

14 Saturday Apr 2018

Posted by sconzani in insects, nature, trees

≈ 2 Comments

Tags

Andricus kollari, gall wasps, galls, galls on oak trees, Marble gall, oak galls, Oak Marble gall, oak tree

180414 Andricus kollari (3)

If you’re a regular around here, you may recall that in August 2017, I posted a mini-series of posts about some of the galls you can find on Oak trees, which included the Oak Marble gall (see the post here). You might also remember that in late October, I was excited to discover a creature had hatched out of one of my galls and I initially thought it was the gall causer, a minute wasp called Andricus kollari. It was not – turns out it was one of the 29 other species of hymenoptera (bees, wasp, ants and sawflies) that can also be found living in an Oak marble gall (more on that here) (and I never did identify it).

180414 Andricus kollari (1)
180414 Andricus kollari (5)

Well, this time, maybe, just maybe, I have seen the gall-causing wasp itself, A. kollari. A while ago, while out walking, I found a small Oak sapling that was absolutely covered in marble galls and, when I found one that had no holes in it, I couldn’t resist bringing it home. The tiny wasp you see in these photos recently hatched out of this gall and the size of the hole it made, plus comparisons with online photos, has led me to think that this time I may have seen the gall causer. I couldn’t be one hundred percent certain of my identification without killing the wasp and getting an expert to check it but I didn’t want to do that. And, of course, I could be totally wrong yet again. In the meantime, the wasp has been returned to the area where I found it so, weather permitting, it can continue its life cycle.

180414 Andricus kollari (2)
180414 Andricus kollari (4)

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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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