Nature Notes from Skye
(and occasionally other places)
Fri 5 - Mon 8 Aug 2005 (Part 2)
Galls were the main purpose of our expedition, though the trip would have been well worthwhile from my viewpoint even if we had not found a single gall. As it was, we found galls galore. It was very rewarding to study galls in the field with the author of the gall "Bible" and gain the benefit of her expertise, and I've come back with a long list of things to look out for on Skye. Each evening after an excellent supper at the Farr Bay Inn we had a microscope session in which we looked at the day's finds.
I only took photos of galls that we haven't already had on this site, and will show all of those here. Some of the photos are in situ, some are obviously posed, and some are made to look in situ but actually posed.
The mite gall Eriophyes kerneri causes the flowers of Autumn Gentian to be replaced with bunches of small leaves. The bud-like gall on Juniper is made up of swollen needles and is caused by the gall-midge Oligotrophus juniperinus. In older specimens the tips curve outwards.
This enlarged fruit of Lady's Bedstraw is the gall of the mite Aceria galiobia. The cauliflower-like flowerheads on Yellow Saxifrage are also mite galls, caused by Aculus kochi.
These are "Little Black Puddings" on Bracken, caused by the gall-midge Dasineura filicina. We also looked for "Cornish Pasties" (Dasineura pteridicola) but didn't find any. The right-hand picture shows a Bracken gall caused by the anthomyiid fly Chirosia grossicauda.
A couple of Rose galls now. These were both on the same bush which was basically Rosa sherardii but may have had a bit of Rosa caesia in it. The leaf fold is made by the gall-midge Dasineura (= Wachtiella) rosarum. (Not to be confused with rose leaf rolls which are made by Blennocampa phyllocolpa which we also saw) The "Rose Pea Galls" are made by a species of Diplolepis, a gall-wasp. If the red spots are papillae, the gall-causer will be Diplolepis centifoliae, but I think they are simply the rose's own glands, in which case it could be any of 3 Diplolepis species.
A couple of "ambrosial" galls now. These represent a three-way association between the host plant, the gall-midge and a fungus, which lines the inside of the cavity in which the gall-midge larva resides. The first is Asphondylia sarothamni which makes its home in Broom pods, and the second is Asphondylia ulicis which enlarges the buds of Gorse and makes its cavity inside them. This latter was quite an exciting find as it was thought to be the first Highland record of this species.
Two more galls on leguminous hosts. The first, on Tufted Vetch, is caused by the gall-midge Dasineura spadicea, which stunts and swells the leaflets and folds them upwards in a crowded mass. The second, on White Clover, is caused by the rust fungus Uromyces trifolii (= U nerviphilus)
The pimples on this Aspen leaf are galls of the mite Phyllocoptes populi. A few are reversed, with the brownish depression that is normally on the underside showing on the topside of the leaf. The other two pictures show an early stage of the fungus gall Gymnosporangium cornutum on Rowan, topside and underside. We also saw the common Eriophyes sorbi on Rowan.
Two rather similar Birch galls, both caused by gall-midges. The first is Anisostephus betulinus and the second Massalongia betulifolia. Both galls look similar on the underside to the topside. Massalongia rubra, Taphrina betulina and Acalitus rudis, which have been shown on the site before, were also found on Birch.
A couple of Alder galls now. The first is made by the moth caterpillar Heliozela resplendella. It makes a leaf mine up the midrib and then makes a branch mine along a side vein - this is yellow-looking in the picture. After going along the side vein for a bit it makes a mine perpendicular to this until it reaches another side vein and then mines back to the midrib. These bits are also yellow in the picture. It then makes a blotch mine, which is the brown area to the left of the midrib near the top. Finally it cuts out an oval piece from the blotch which falls to the ground and is attached to other leaf litter by the caterpillar, which then pupates inside the detached oval piece of blotch mine. The caterpillar counts as a galler because it causes the midrib and veins to swell while it's mining them.
The second Alder gall is caused by the fungus Taphrina tosquinetii, which can swell the leaf up to twice its normal size. The picture shows an early stage with just one section of the leaf swollen. After the whole leaf is swollen it often turns a dull pinkish colour.
Other Alder galls seen were Taphrina alni, Eriophyes inangulis and Eriophyes laevis, all of which we've had on the site before.
Two Willow galls. The first is a leaf roll on an Osier-Sallow hybrid, made by the gall-midge Rabdophaga marginemtorquens. (Note to other attenders: I've discounted the possibility of R clausilia since in the amendments to the gall book it says this half of the couplet should be omitted). The second is a roll of both margins made by a Phyllocolpa species of sawfly. This is not in the gall book as it was not formerly thought to be a gall, but now it is. From info on the web I'd guess the species is Phyllocolpa leucosticta. Other willow galls seen were Iteomyia capreae, Iteomyia major, Rabdophaga rosaria, Aculus laevis, Melampsora caprearum and Pontania bridgmanii all on sallows, and Pontania collactanea on Creeping Willow, which have all featured on the site before, and Pontania pedunculi (on sallows) which has not.
The spectacular fungal gall Puccinia punctiformis on Creeping Thistle, which makes the whole plant distorted and sickly looking and covers the underside of the leaves with brown rust.
A couple more galls on Composites. The gall-midge Rhopalomyia millefolii causes these swollen buds in the leaf axils of Yarrow, while the larva of the gall-fly Tephritis leontodonis lives in the flowerheads of Autumn Hawkbit causing distorted growth. This one has been opened to show the white larva.
This leaf roll on Hawkweed had aphids in it, probably Nasanovia nigra, the only aphid gallers of Hieracium in the book. A great many plants also have root galls which can't normally be seen for obvious reasons. These are the root nodules on Bog Myrtle caused by the nitrogen-fixing actinomycete bacterium Frankia.
Other galls seen and not so far mentioned were: Aceria thomasi on Thyme, Jaapiella veronicae on Germander Speedwell, Brachycolus cerastii on Common Mouse-ear, Contarinia barbichi on Birdsfoot Trefoil, Dasineura pustulans and D ulmariae on Meadowsweet, Dasineura urticae and Puccinia urticata on Nettle, Livia juncorum on Jointed Rush and Eriosoma ulmi on Wych Elm. We've had all those on the site from Skye specimens apart from the Brachycolus and the Contarinia, which I didn't get a chance to photograph as I was elsewhere when they were found.
The next page will show various effects on plants that are (probably) not galls.
All photos and other content copyright © Carl Farmer