Population Ecology of Culex tarsalis (Diptera: Culicidae) in a Foothill Environment in Kern County, California: Temporal Changes in Male Relative Abundance and Swarming Behavior

Abstract

Male Culex tarsalis Coquillett swarm during the transition in illumination at dusk and dawn. Swarms formed earlier in spring and fall than in midsummer and lasted longer in relation to sunset. The time of swarm formation expressed in crepuscular units was correlated positively with temperature during the mosquito season. The relative abundance of males in swarms was not correlated temporally with the abundance of males resting in red box shelters and was inversely correlated with temperature. Pairing occurred concurrently with swarming activity; however, the observed number of mating pairs seemed insufficient to account for the insemination rate in the study population. Males usually formed either “top” or “space” swarms above or between small trees or bushes, respectively, but occasionally formed “marker” swarms with changes in ground coloration. The same swarm sites were utilized repetitively; however, alternative sites such as the vehicle or the observer's head were also utilized. Data from mark-release-recapture studies indicated that male swarming continued each evening of life and that swarming within “spaces” may be selected from the natural population during colonization.