The use of plant secondary metabolites synthesized by some plant species as part of their natural self-defense against pathogens and pests seems to be an excellent alternative biopestici-des are more and more popular with food manufacturers and consumers equally. Biopesticides could grow from 4–5% of the global pesticide market to as much as 20% by 2025 [1]. The important bioactive compounds of neem seed oil belong to the limonoid class of triterpenoids, such as azadirachtin, nimbin [2]. Extracts of rhubarb roots and leaves are a source of various biologically active substances such as emodin, quercetin and oxalic acid [3]. The purpose of our research was to determine the biological effectiveness of plant extracts in protecting of cu-cumber seedlings from spider mites.