We examined the effects of trichomes and the glandular trichome exudate on the survival of the predatory mite Amblyseius swirskii on young potted tomato plants. Removing the trichomes from the plant surface increased the survival rate from 0.8% (untreated plants) to 12.2% and decreased the mortality on plants from 63.3% ( untreated plants)to 0%. Almost all of the dead mites on untreated plants were observed adhering to the sticky secretions from trichome glands. To evaluate the toxicity of the secretions, we tested the effects of its main components (2-tridecanon and 2-undecanon) on A. swirskii by exposing mites to these chemicals for 48 h. All mites survived treatments with either of the chemical concentrations alone or a blend of these two chemicals. These results suggest that the main cause of the mortality of A. swirskii on tomatoes is not the toxicity of the secretions, but rather adhesion to the sticky secretions from the glandular trichomes.