Abstract: The California red scale (CRS) was detected in citrus in Cataluña in 2000. Up tonow, this pest has showed a slow spread, and currently different foci of infestation can befound in all directions in the Southern Tarragona citrus-growing areas. Most of the infestedorchards show irregular presence in scarce trees and low populations. Thus, often thesepopulations are only detected during harvest. Since 2002 male flights were monitored withsticky yellow traps lured with CRS pheromone. Population dynamics showed that 4 maleflights occur (including that of the overwintering generation) in May, mid June-mid July, inAugust and during October, being the third one the most abundant. The thermal constantestimated between male flights, using as lower threshold temperature 11.7ºC, was 611.8 ±35.5 DD. The CRS life cycle was followed in 2006, 2007 and 2009, since the rest of theyears pest populations were not high enough to carry out this study. Three peaks of first (L1)and second (L2) instar nymphs were observed: early June, late July-early August, and lateSeptember. The percentage of L1+L2 achieved was 70.1%, 57.9% and 46.1% respectively.Sticky tapes wrapped around twigs revealed that crawlers begin to be trapped at the end ofApril-early May, and reached its maximum at the end of May.