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An overview of knowledge about the horse chestnut miner Cameraria abridella Desch. & Dem. (Lep., Gracillariidae), a pest developing in leaf mines of Aesculus bippocastanum, spread gradually from the Ohrid-Lake (Macedonia) through Bosnia, Serbia and Croatia up to the central Europe (fig.). At present (1999) it occurs in northern Italy, Switzerland, Hungary, Czech and Slovak Republics, Austria, southern and central Germany and in southern Poland. Usually three, but up to five generations develop a year in central-European conditions. C. obridella develops also in leaf mines on Acer pseudoplatanus and A. platanoides. The parasitation is 1–8% and seems not to increase. Heavily attacked trees do not die; only rarely the dying of heavily damaged trees have been observed. Several insecticides may be used to control of this pest. The most successful was the growth-regulator Dimilin with active substance of Diflubenzurol. In the future it will be possible to control populations of Cameraria obridella by pheromones. The future development of this pest and its control is discussed. [ABSTRACT FROM AUTHOR]

Cameraria ohridella was recorded first in 1985 in Macedonia. It gradually expanded to north and west and at present it is a serious pest of Horse Chestnut Aesculus hippocastanum in the Czech Republic, having been established at about 80 localities. There are 4–5 overlapping generations with sizes of the larvae of 0.4–4.0 mm. The larva develops inside the leaf tissue in the upper parenchym layer of the leaflet and causes a mine, the size of which is broadened with growing larva. First adults start to fly at the end of April. After mating the females lay single eggs on the leaves. Larval development lasts 25–30 days followed by the prepupa I and II. The latter spins a cocoon in which the pupa of the last generation hibernates. The development from L4 to the prepupa lasts for 3–6 days at 22°C. During the summer it is possible to find all larval and prepupal stages in attacked leaves. Four Aesculus species: A. parviflora Walk, A. carnea Haey., A. glabra Walk and A. indica J. Hobb. were found to be resistent to C. obridella. A. lutea H. J. was liftle and A. pavia L. was heavily attacked. The parasitization of C. o. larvae was very low. Only 2 parasites were found in 1500 mines in the first and second generation of C. o., and 40 parasites in 1000 mines of the fourth and fifth generation. The highest mortality takes place in moths, eggs and young larvae. It was found in all 4 generation that there were i. m. 50 eggs/leaflet from which i. m. 3 hibernating pupae resulted. Supposing 2 moths (1♀, 1♂)/leaflet emerged in spring which produced 50 eggs (75 eggs/♀—33% moth mortality), the density of eggs in the first generation after hibernating being the same as in the last (fourth) generation before hibernating. As to the whole populations density in this case we can calculate as following: 3 pupae/leaflet on the tree=3000 pupae/leaflets pro m2 on the soil=2000 emerging moths pro m2=50,000 moths (25,000 ♀♀) pro tree (namely 25 m2 projecting area of the tree crown×2000 moths). [ABSTRACT FROM AUTHOR]