Figure S2 WNV titers in Culex pipiens quinquefasciatus hemolymph at early time points. Mosquitoes were offered a WNV Mix24 infectious bloodmeal and hemolymph extracted at multiple time points. WNV titers were determined by plaque assay. (TIF) Figure S3 Bayesian trees with the most parsimonious reconstruction of tissue character states from the six remaining mosquitoes. Blue = input (i), pink = midgut (m), gold = legs (l), black = salivary secretions (s), dotted = multiple tissues, with specific tissues indicated by abbreviations. Hatched branches indicate equivocal reconstruction of character states. Numbers above the nodes are the posterior probabilities inferred for each clade. Mosquito analyzed and most parsimonious reconstruction of ordered character steps for each tree is as follows A) 7 dpi mosquito 1 (21 steps, p = 0.0002) B) 7 dpi mosquito 3 (10 steps, p = 0.0057), C)14 dpi mosquito 2 (8 steps, p = 0.087), D) 14 dpi mosquito 3 (23 steps, p = 0.0002), E) 21 dpi mosquito 1 (12 steps, p = 0.0772), F) 21 dpi mosquito 2 (16 steps, p = 0.007). (TIF) Figure S4 The proportion of wild-type WNV when competed against a marked reference virus does not References 1. Randolph SE, Rogers DJ (2010) The arrival, establishment and spread of exotic diseases: patterns and predictions. Nat Rev Microbiol 8: 361–371. 2. Anderson JF, Vossbrinck CR, Andreadis TG, Iton A, Beckwith WH, et al. (2001) A phylogenetic approach to following West Nile virus in Connecticut. Proc Natl Acad Sci USA 98: 12885–12889. 3. Beasley DWC, Davis CT, Guzman H, Vanlandingham DL, da Rosa A, et al. 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