The miner fly Liriomyza sativae (Blanchard) (Diptera: Agromyzidae) is an insect of economic importance for tomato culture. The conventional control with insecticides is complex due to the mining eating habit that provides protection to the larvae inside the leaves. Therefore, farmers can opt for biological control agents, or substances that provide protection to the plant. Thus, the objective of our research was to evaluate the use of silicon to induce resistance in tomato plants against L. sativae. The results showed that in tomato plants treated with SiO2/F and K2SiO3/F there was a reduction in the net reproduction rate (Ro), in the intrinsic rate of increase in number (rm), in the finite rate of increase (λ), in the average interval between generations (IMG), in the doubling time (TD), in the number of eggs/ female/day and the accumulated egg laying of F1 females of L. sativae. The products SiO2/F and K2SiO3/F gave the tomato a protective effect against injuries caused by L. sativae.

The presented studies revealed the usefulness of spruce oil, basil oil, juniper oil and clove oil in monitoring of the occurrence of pea leafminer (Liriomyza huidobrensis Blanchard). While using above mentioned oils on yellow sticky traps, it was found that the number of trapped insects increased significantly. In relation to the control (traps without any addition of aromatic substance), the increase amounted to: 561.33%, 287.95%, 159.74% and 130.77%, respectively.

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.