Recently, considerable attention has been paid to climate change effects on nature and abundance of pests affecting agricultural crops. Our study was focused on the trends in aphid abundance during the growing seasons in spring barley in 1976–2007. Analysis was conducted based on the records of aphid abundance observations and detailed meteorological data. The first step in the study was to clarify the effects of temperature on aphid occurrence and abundance in spring barley. This part of the study was restricted to Dotnuva site, which is a typical area for commercial crop production, in order to reduce the influence of such effects as management, macroclimate, soil and others. A distinct and statistically significant increase in the mean air temperature was noted at the experimental site of the Lithuanian Institute of Agriculture in Dotnuva, Kedainiai for the period 1976–2007. A statically significant positive trend was identified for the mean air temperature during April–November. Consequently, during the last decade the occurrence of aphids has also become quite frequent.