Table 1.

Adult female mosquitoes (N=7,936) collected during July-August, 2013, at four sites in Larimer County and tested (pools ≤50) for viral RNA by RT-PCR, according to collection method. Engorged mosquitoes were screened in pools of eight, and retested as individuals if the screen was positive. To calculate the infection rate, they were treated as pools of one. Other than West Nile virus (WNV), only Flanders virus was detected (in Cx. tarsalis, see text). CI, 95% confidence interval.

Species	Collection method	Total female mosquitoes	Pools tested	WNV detections by RT-PCR	WNV I.R. per 1000 [CI]
Culex tarsalis	CO2	1,719	70	21	15.6 [9.9–23.7]
	Resting	828	301	6	7.3 [3.0–14.9]
Culex pipiens	CO2	308	30	1	3.3 [0.2–15.9]
	Resting	1,151	526	13	11.9 [6.7–19.8]
Culex restuans	CO2	1	1	0	0.0 [0.0–793.4]
	Resting	2	2	0	0.0 [0.0–657.6]
Culex erythrothorax	CO2	1	1	0	0.0 [0.0–793.4]
	Resting	1	1	0	0.0 [0.0–793.4]
Culiseta inornata	CO2	9	4	0	0.0 [0.0–220.1]
	Resting	77	19	0	0.0 [0.0–39.7]
Aedes vexans	CO2	2,751	86	1	0.4 [0.02–1.75]
	Resting	91	11	0	0.0 [0.0–32.0]
Aedes dorsalis	CO2	390	21	0	0.0 [0.0–8.7]
	Resting	3	1	0	0.0 [0.0–408.9]
Aedes melanimon	CO2	182	9	0	0.0 [0.0–16.3]
	Resting	22	10	0	0.0 [0.0–119.9]
Aedes trivittatus	CO2	205	19	0	0.0 [0.0–14.4]
	Resting	2	2	0	0.0 [0.0–657.6]
Aedes nigromaculis	CO2	12	1	0	0.0 [0.0–123.2]
	Resting	0	--	--	N.A.
Aedes hendersoni	CO2	16	3	0	0.0 [0.0–124.1]
	Resting	1	1	0	0.0 [0.0–793.4]