Spring Gall Hunting in the English Midlands
@sk53 here.
I wrote a journal post about my first day looking for galls around Nottingham, my home in the East Midlands of England. One of this project's originators, @merav, gave me permission to post the journal here.
I'm going to try posting each day's gall hunting as a comment to this journal.
Day 1
Spring Gall week 2023 comes a week or so too early for central England. This year Spring has come slowly, and in fits and starts, with the result that leaf bud burst is only just underway for most trees.
Usually the first new galls of Spring are eriophyid galls on newly unfurled leaves, with Acer, Salix and Crataegus often galling as tge leaves open (I believe the mites overwinter within the bud scales, so can move in immediately). Cecid gall causers tend to be a bit later: early ones are Semudobia sp. Ovipositing into female Betula catkins, and Dasineura tiliae, but neither host is ready yet. Oak Apples should be forming now, but I have only one location close by where I've seen them. Other cynpids on Quercus must await the catkins.
All of this means my initial hunt relied on old galls, a few rusts, and some eriophyid big buds, leaving only about 3 currently tenanted galls out my first day's haul of 17 galls:
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Trioza centranthi. Until 6 years ago this psyllid could not over-winter inland in Britain. A colony was discovered in Leicestershire by Graham Calow in October 2016. I then found it in two locations in Nottinghamshire in early 2019, and discovered one more on checking photos taken even earlier (1st January). Four years down the line the galls are ubiquitous locally, and appear rapidly on new seedlings.
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Aceria cephalonea. This required close examination of newly opened Sycamore leaves, the bumps although reddened are still small, and anthocyanin pigments mask the color difference.
In terms of likely suspects for the remainder of the week, I only have a handful of obvious targets: Marble Gall, two Semufobia, Hollyhock Rust. If leaf burst continues I might find Aceria macrochela, A. myriadum., and Phyllocoptes goniothorax (for some reason both the latter two are quite scarce close to me). A couple of fungal galls are also possible : a smut on Winter Aconite leaves, and both a smut and a rust on Lesser Celandine. The gall I've failed to find this year, which for some reason is a late Winter one locally, is Dasineura violae. All-in-all I don't expect to get to 30 galls in the week. For comparison in early May 2014 I led a gall walk at Attenbourough NR where we found 50 galls in a couple of hours (more eyes does make a big difference).
Comments
Interesting reading. You are obviously ahead of us over in the East Midlands - here in the West Midlands, on the Shropshire border with Wales, altitude 420m, we are about a month too early. The first Blackthorn flower opened today and Hazel and Hawthorn leaves are just starting to emerge from their buds. I have just managed to reach double figure (10), with half of them fungal causers. Like you, Trioza centranthi is a 12 month sure bet, since first arriving four or five years ago. Saw the first Cecidophyes rouhollahi on Galium aparine yesterday. The two Taxus galls have both turned up in the garden, possibly helped by the fact that I didn't clip the Yew last year.
@johnlyden It's been a slow Spring here, but there's barely a flower left on the blackthorn (not sure what it means for sloes in the Autumn). Seen my first Elder and Hawthorn flowers today, some Hazels are fully in leaf (about 10m lower than here, but I presume genetics is more significant as they flower 3 weeks early too). Aside from altitude, I think there have always been noticeable differences between East & West wrt galls. I should find out as I will be in Cheshire at the weekend. My haul today were all old galls, but I may make an excursion to find Taxomyia taxi on Wednesday in another local churchyard. Butterflies are still patchy, not had a good glimpse of a Speckled Wood yet.
@sk53 Wife is from Leicestershire, so Im used to the spring and summer being advanced and autumn delayed over east. I have a box that I have left unclipped for two years so I shall be having a fossick tomorrow. I'm also heading off to a churchyard in the afternoon to look for T.taxi and Cecidophypsis psilaspis - they won't add to the species count but I'm trying to tick a few vc40 squares.
Day 2
I started the second day with the Holm Oak Felt Gall Aceria ilicis,, which I'd forgotten about. This has been around for at least a decade or more, but never as profusely as I have seen in Berkshire. It is present on nearly every Holm Oak, but may require fairly diligent searching. In this case I had to check two trees. There were lots of two lepidopteran leaf mines, both relatively recent arrivals.
After coffee i went in search of the targets mentioned at the end of Day 1. No Marble Galls were to be found on a group of fastigiate oaks, but they did yield a couple of examples of an unexpected gall: the sexual generation of the Silk Button Gall Causer Neuroterus numismalis. It's noticeable that smaller oaks have not retained their dead leaves this winter so I was lucky to find these galls on the the 3-4 leaves.
The next stop were some likely looking Silver Birch with plenty of branches and twigs at shoulder level. I was looking for the two Semudobia galls in old catkins. Again many birches have retained fewer of last years catkins. These trees were in a sheltered spot and had enough to look through. These galls are tiny, being within the fruit of the birch, which itself not very big. However, they are everywhere: a typical catkin may contain 10 infected fruits out of 300. So all that is really required is a bit of patience, a hand lens, and no wind. If windy I just bag up the disintegrating catkin and search when i get home. This time I found both types of galls in the first catkin I looked at as well as the other Semudobia which I'd seen on the first day. I then found S. betulae in a second catkin. It's always a bit easier to spot because the gall causer leaves a 'window' in the fruit. tarda on the other hand is distinctive as the fruit lacks wings entirely, but is less easy to pick out. There are astonishingly few records of these galls on iNaturalist, and under 300 on GBIF. If you live in Europe and have birches nearby they are certainly worth a look. Even in North America, I'd give it a go. I've found at least one in River Birch catkins here in Nottingham, so if they're at all widespread in North America you may find them.
Some tips: at this time of year look for old catkins retaining both seeds and bud scales. Take the catkin holding it at either end and gently twist it to release the bud scales and fruits. You may need to gently brush some recalcitrant ones off, but do it gently, as ones stuck the rachis of the catkin may well be Semudobia skuhravae. To start with take the rest home, place on a white surface (a petri dish is ideal) and with a small paint brush push the catkin scales to one side as they obscure the fruits. Again using the brush now sort through the fruits: non-galled ones have obvious wings and can usually be dismissed. A hand lens or microscope can be useful at this stage. Beware some birches might not be fertile: usually obvious as the fruit will be undersized.
round the corner were a couple of Common Mallow rosettes. As these get heavily mowed, I feared their leaves might not be old enough to have been infected with Hollyhock Rust, and indeed I drew a blank on the first, but found a couple of obviously infected leaves. Funnily later in the day I saw a much bigger plant, but it's leaves were clean.
My last new gall of the day was the target of m afternoon walk. An old churchyard has a big display of Winter Aconites and this is about the time when most such leaves start showing blisters caused by a smut Urocystis eranthidis. This is common, but I've lost these plants from the garden so I chose a site likely to have lots of it. It didn't take long, and I got the bonus of a White Comfrey reported by @melica a few weeks ago. So common is the gall I've wondered if the infection is really just part of a natural senescence process.
This was a more productive day than I expected, with my main target species being located, except for Marble Gall, which remains the main goal for Day 3.
Very big year for Dryocosmus floridensis in my neck of the woods. Disappointed in not finding any Amphibolips on my property, but I did finally find Aceria nyssae and Aceria dina here (seen previously at nearby preserve). Going to Turkey Creek unit of Big Thicket NP tomorrow and Roy E. Larsen Sandyland Sanctuary Thurs or Friday. And at some point I'll make it over to Watson Rare Native Plant Preserve to photograph some Amphibolips I spotted last week.
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