Apparently there can be four to five generations per year in Connecticut where there has been research done on this pest. I couldn't find anything on generation time for the population in the west.
Scudder, G.. Heteroptera (Hemiptera: Prosorrhyncha) New to Canada. Part 2. Journal of the Entomological Society of British Columbia, North America, 101, 2004. Available at: <http://journal.entsocbc.ca/index.php/journal/article/view/76>. Date accessed: 13 Feb. 2015.