Coloured sticky traps are one of the most important tools for monitoring greenhouse pests. They allow to determine the need or appropriate time of treatment applications against phytophagous, evaluate effectiveness of previous control actions and reduce their number. The study was carried out in a greenhouse of the Maria Curie-Skłodowska University in Lublin Botanical Garden from March 30, 2005 to March 30, 2007 and was aimed at determining the population dynamics of Ctenosciara hyalipennis (Meigen) as well as the efficacy of two types of sticky traps in monitoring the number of the pest. During the study a total number of 12 263 specimens of this species, had been caught. These insects were the most numerous on yellow traps (7 915 specimens). During the entire study period some significant differences were demonstrated between the daily number of C. hyalipennis in relation to the color of traps. In season I, the mean number of this species specimens caught during a day on a trap was 2.75 for yellow traps and 2.59 for blue traps. During the study season I (30.03.2005–28.03.2006), the maximum of abundance was recorded from the third decade of May to the second decade of June, 2005 and in the third decade of March, 2006. In the study season II (28.03.2006–30.03.2007), the median of this species was 2.52 specimens. In this case the highest abundance of C. hyalipennis was observed from the beginning of the season to the first decade of May, 2006. An average number of this species caught on blue traps during a day was 1.88 specimens. The study proved that coloured sticky traps may be a useful tool in monitoring the presence and density of sciarid flies in greenhouse production. Yellow traps appeared to be more effective in monitoring and catching adult specimens of C. hyalipennis as compared to blue traps. However according to the literature, yellow sticky traps capture more natural enemies than other colours. Blue sticky traps can be also used to monitor the C. hyalipennis population in greenhouses production where biological control program is applied.

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