Triplots showing Relative Invasion Risk of T. s. scripta, T. s. troostii, S. odoratus and K. subrubrum in a Great British context. Invasion Risk is calculated as a product of maximum feeding rate, lifespan and Pet Propagule Pressure (PPP) (a), with fecundity (b) and with lifetime fecundity (c); then attack rate, lifespan and PPP (d), with fecundity (e) and with lifetime fecundity (f). PPP for each species calculated by surveying classified advertisements online and finding what proportion were selling the species in question. Invasion Risk increases from bottom left to top right of each plot, with species ranked 1–4.