Observations on the development of the horse chestnut leafminer on red horse chestnut (Aesculus x carnea H.) were carried out in Wrocław, Lower Silesia, Poland, in 2001–2003. Three generations of the pest were recorded to lay eggs on the red horse chestnut leaves. Although females of each generation deposited eggs abundantly, the hatching larvae died after a short period of feeding in the plant’s leaves and the species did not complete its development on this tree. Mostly L₁ and L₂ larvae were found inside the leaf mines. The observed leaf damage was, therefore, negligible.

Observations on the incidence, harmfulness and some elements of Cameraria ohridella control on white horse chestnut (Aesculus hippocastanum L.) were carried out in Wrocław, Poland, in 2001–2003. Three generations of the pest developed on A. hippocastanum. The leaf infestation by pest’s larvae increased systematically throughout the spring-summer season. Cultural control by removing the fallen leaves was suggested. Using this procedure, the abundance of the pest was considerably reduced, therefore, the percentage of the leaf damage was lower and the trees lost these leaves later in the season.