When I saw plant galls for the first time I wanted to know what species there were to be found basically, and so I started collecting anything that looked like a plant gall. Boxes full of them I have now. Nowadays I think it is better for me to take pictures (digital or slides) and when you are interested in the gall maker itself, it is a good idea to try to get the inhabitants to emerge from the galls. The list of species described below are gall makers and their hosts, from species that I myself or another gall studying person has seen. A description is given and, where possible, a picture. For people who are interested in the Dutch distribution of pant galls can soon take a look at the database we are preparing for this website. Since the subject of plant galls becomes more popular only recently, we do not have yet such an extended database. Any contribution is welcome!
|Click on the pictures to view it larger|
In Schandinavia you can find Cirsium helenioides, like I have seen in Norway, and of course there is a gall causing insect occuring on this species. But what species? I asked Carl-Cedric Coulianos, author of 'Galler' (1991), about this and he was able to tell me that the gall is caused by a midge. It has been found in Sweden as well, Torne Lappmark, Nuolja (See B.Palm Aufzeichnungen uber Zoocecidien. I-III- Svensk Botanisk Tidskrift 17:30-61, 1923, with a drawing on page 33). The species is also mentioned by Buhr as gall No 1853.The galls look somewhat like the ones you can find on Sonchus or Taraxacum and perhaps it is related to Cystiphora. My first glance at the leaf with galls made me think of Sochus and not Cirsium.
Anisostephus betulinus is a gal midge that causes somewhat shiny untransparant blisters in the leaf blade of birch. The galls are circular and do not bulge much. Surrounding the pale yello-green gall you can often see a red coloured circle. The galls are 2,5 to about 4 mm in across. The larva is white at first and yellow later. According to Redfern the larva has a conspicuous sternal spatula. I think the galls are most common on B. pubescens, but maybe people have seen the galls also often on B. pendula.
|Arnoldiola quercus causes galls at the terminal buds and axial buds of Quercus robur and Q. petraea. The galls look like the ones of Andricus fecundator, but the number of scales is less and the gall has a less tight appearance.|
|Contarinia aequalis - In Altenau, Germany, I found a gall on Senecio ovatus that is probably caused by Contarinia aequalis. It was already very special to find Senecio ovatus. The gall was not very clear and I only found one specimen.|
|Contarinia craccae causes a nice nest for themselves in the flowers of tufted vetch,Vicia cracca. This makes the flores deforme to tight and round whitet-purple shiny globes.The larvae are pale orange-yellow. The pictures were made in Juli 2006, at Svarava, Tjechia. Floris Grotenhuis noticed the galls in Vaals, in the Zevenwegenbos (a wood) july 2009 in the Netherlands (http://people.zeelandnet.nl/grada/gallen/).|
|Contarinia jacobaeae lives in the flower heads of Jacobaea vulgaris and relatives, like Senecio vulgaris. The flower heads remain sort of closed and have become fleshy and coloured yellow to red. Yello white larvae live between the flowers.|
|Contarinia nasturtii is to be found on several species of Brassica, which is why the midge is called Koolgalmug in Dutch.The species is rather common in the Netherlands, and I also found some in the Pyrenees. The midge can also cause galls to form on the leaves but on this picture I found them in the flowers. The flowering bud was closed and globule shaped.|
(two bottom pictures: K. Raangs)
|Contarinia quinquenotata - At plant nurseries and other green places in the Netherlands people look a bit more than average at the plants and their visitors. That is why lately I receive messages about galls from nurseries. Brian Kabbes from the Suameer sends me a picture every now and then and Arborealis in Elsloo always have something to show me when we pass by. The picture here shows a Hemerocallis from Kabbes with a Contarinia quinquenotata for a guest. The flowers develop badly and hardly open up when they are young (Docters van Leeuwen, 1982). Elderly flowers have twisted coronella edges and the sexual organs are not very much developed. The larvae are brownish.|
|Contarinia tiliarum is a species that is rarely seen on Lime (Tilia sp) in the Netherlands. The galls consist of swellings in petioles, flower stalk or young stems and have a pale colour and a globular shape. The galls are hard and later turn green and often become reddened. They are 2 to 15 mm in size and sometimes extend into the main vein of leaves and bracteoles. The gall may contain one to many gall chambers with a pale yellow larva.|
|Cystiphora taraxaci At Eimke in Germany I first found this on Taraxacum officinale. These are little round shapes half of a centimeter in diameter that hardly stick out. The round shapes colour slightly darker and sometimes dark purple. It is wise to take pictures from fresh samples, so the contrast between galls and leaf remains visible.|
|Dasineura aparines is commonly found on Galium aparine. The shape is a lot like the description mentioned in Docters van Leeuwen (1982), but I didn't notice the white colouring. Maybe it was not the right time for it to be shown. Also, the galls weren't very broad, usually just about five centimeters. The galls are very loosely shaped rosettes only to be found at the tops of the stems.|
Dasineura hyperici on Hypericum perforatum causes the similar gall as Dasineura serotina, with swollen folded top leaves. The two species can only be distinguished when rearing the midges.
|Dasineura irregularis - The curled leaves of Acer campestris that I found in 'sGravenland, Engeland and Altenau, Germany, are caused by Dasineura irregularis. As well as in Docters van Leeuwen (1982) as in Stubbs it is written how the nerves are partially thickened. The species also occurs on Acer pseudoplatanus.|
|Dasineura marginemtorquens causes leaf edges to roll upp tightly and the plant cells become enlarged. This gall can be found on Salix purpurea, Salix viminalis and I think also on Salix fragilis. The galls are often spotted with red and yellow. The larvae are pale orange and in August they lool like the picture on the right.|
|Dasineura ruebsaameni galls can be hard to distinguish on the leaves of Carpinus betulus. I've only come across this gall once in Twente. The galls only stick out a little bit from the upper and lower side of the leaf. In Docters van Leeuwen (1982) it states the galls become about four millimeters if you take a longitudinal section, but in my case it only seemed to be two.|
|Dasineura serotina - On Hypericum perforatum is not a rare species where Hypericum is growing. With folded leaves and the white midgelarvae in between. (also see Dasineura hyperici).|
Dasineura sisymbrii creates a sponge-like swelling in de flowering parts of the plant (?). The shapes have a white/ pale yellow colour and at about Augustus little slits appear to allow the midges to emerge. The plants are often partially still capable of producing flowers and seeds.
|Dasineura trifolii Klöverbladgallmygga (Swedish). This midge causes a leaf gall. The two halves of the lea fare folded together around the central vein. The area around the central vein is a little bit thickened and irregular. The thickened part is coloured red or pale green to yellow. The gall midge larvae are pale orange. I found this specimen along the road side in Sogndal, Norway.|
(Picture: P. Koster)
|Didymomyia tiliacea creates two parts in the leaf blade of Tilia species (lime) that come apart when the inner gall falls to the floor at the end of summer. The gall mostly protrudes on the upper side of the leaf and has the shape of a cone. The part on the underside of the leaf has a more round shape. The entire gall can become 6 by 4 mm, is green at first and the upper part later turns brown or yellow. The larvae are yellow. The inner gall is cilindrical of shape and after this part falls to the floor at the end of summer the remains of the gall on the leaf keep growing so the hole were the inner gall came out is filled again. The inner gall remains on the ground during wintertime and in the Spring a small hatch opens to the midge.|
|Geocrypta galii on Galium verum I have seen in the Alps, in the Pyrenees, and in the south of Belgium. If you find a specimen it is best to immediately take a picture. While drying the spongy gall shrivelled completely so later on the beautiful shapes of the gall are not to be seen again. The galls appear to be placed at the top of the stem and they are sort of round or oval of shape. The colour is light green and yellow and a little reddish or purple. There is often a lot of white on the galls. When the midges emerge an opening becomes visible like the folds of an envelope. The galls are easy to spot because they are just as striking or even better than the flowers.|
(Picture: R.J. Koops)
|Harmandia globuli on Populus tremula is a common species in Scandinavia. It induces round, smooth globular shapes to grow on the upper surface of the leaf. The galls are slightly pink to red at first, but soon turn bright red and later fade to a very dark blackish colour.|
|Hartigiola annulipes makes round, hairy cilindrical shapes on the upper side of the leaf of Fagus sylvatica. I have seen the gall in many places. It is common but very beautiful. The cones are four to five millimeters and golden hair is planted on its surface.Sometimes the galls are covering the leaves so much you would think it would become a pest to the plant. This picture was made in Ness Botanic Gardens, England.|
|Iteomyia major The common gall Iteomyia major is found on Salix aurita and S. caprea. The galls have a globular shape and appear on both sides of the leaves. They are pale green/ yellow. The entrance is at the underside of the leaf and clearly visible. According to Docters van Leeuwen (1982) several galls can grow to become one gall, so you have a larger gall with more than one chamber.|
|Lasioptera rubi you can find on several species of Bramble. Sometimes they look like globules, but they can also be shaped as slightly thickened parts on branches which makes it harder to spot the galls. The ones I've seen were never any thicker than one and a half centimeters. It seems they also appear on stalks of leaves, but I have never seen such a thing. Maybe you have?|
Loewiola centaureae causes discolouration between the vains of the leaves ofCentaurea scabiosa (?) the galls are pale yellow- green and have a thick dark purple edge. The gall shows a slight elevation from the leaf at both sides, with a longshaped depression in the middle. The galls on this picture I made in Savognin, Zwitserland. The species is supposed to be rather common in the UK as well, but unfortunatelly the host plant is not so wide spread in the Netherlands as in our neighbouring countriesbuurlanden. I have never seen the species in the Netherlands anyway.
|Macrodiplosis dryobia is a midge that folds the lobes of leaves on Oak. The part that is folded is slightly thickened and lighter coloured. In between you find a white larvae.|
|Massalongia rubra produces galls in the midrib of the leaf of Betula pendula or birch.On the upper side there are clear swellings visable and underneath is a red-brown discolouration at the place of the gall. Underneath you also find the exit of the gall.|
|Mikiola fagi is a most beautiful gall on Fagus sylvatica. The first time I found the galls on a variegated specimen of Fagus, but later I saw them growing in the Hartz in Germany. In Germany the galls almost completely covered the leaves. Now I also spotted the gall in several parts of the Netherlands, but never in the Northern Provinces. The Mikiola galls have a lovely dark brown or reddish or yellow or green colour, depending on the colour of the host plant. You can find them anywhere on the veins of the top side of the leaves. They are like little eggs that end in a pointy center.|
|Oligotrophus juniperinus is a midge commonly found on Juniperus communis. Unfortunally this shrub is not very common in the Netherlands, but more common in bordering countries. The two last levels of leaves are involved in the galling process. The outer part is formed by enlarged and thickened leaves that are green at first, but turn to a more yellow and eventually brown colour later. In between these leaves are some smaller leaves, that get a brownish colour. They enclose the one orange larva.|
|Rabdophaga justini is probably the name for the gall midge that causes this gall onSalix fragilis and according to literature also on Salix purpurea (Redfern et al. 2002). On the upper side of the leaf blade it shows an irregular pustule and underneath the leaf is no bulch, but only a slit-like opening.|
|Rabdophaga rosaria I found on Salix repens, but you can also often find them onSalix alba a lot. In the Netherlands the midge is very common. I recently heard about plant propagators that are trying to find a way to prevent the midge invading their crops. They think of the midge as being a pest because they live in the new growing shoots. In winter I personally become very happy watching the willows filled with rosettes. This is the time of year when it is merely possible to find some galls formed on branches and other parts of plants that remain in winter. When opening a gall earlier in the year you will see a weak red larva. The gall becomes a rosette due to the internodes growing very close to one another. The midges only have one generation every year.|
|Rabdophaga salicis or Wilgetakgalmug I discovered on Salix aurita, but you can also find it on S. cinerea and S. caprea. It is a fantastic gall looking like two galls on top of each other merged to one shape. The globules contain several gall chambers. Sometimes they become up to five centimeters long and up to a full centimeter wide. They are easy to spot as they grow on the more thinner branches, that means in the top of the bushes.|
|Rondaniola bursaria creates funny galls on Glechoma hederacea. In the summertime you see purple hairy cones on top of the leaves. At the end of summer, only perfect round holes, where the galls used to be, are left. The cones are some millimeters high and there are usually a couple an each leaf. It is rarely that the leaf is crowded with galls.|
Taxomyia taxi or 'Taxusgalmug' on Taxus baccata is a rather common species in the Netherlands. The gall is formed on young buds on young twigs. The gall looks like a rosette and the needles are slightly smaller than usual. Pruning or no pruning seems to make a difference to the abundance. When you connect that to the fact Dutch people like to prune everything neatly in shape, you could conclude it is the reason for its absence at some locations. From Ben van As I received a finding from Bekendelle in the Achterhoek in the Netherlands. This was just on one tree in that area. The galls have a life-cycle of two year and at the end of their second year the galls become really big (see picture) and the centre part (with the actual gall in it) is released from the outer gall. On Box Hill in the South of England I found my first Taxomyia taxi, but I think I can say this gall can be found anywhere in England.