For one year we studied the habitat use of Peucetia viridans living on Cnidoscolus aconitifolius, in a pasture land in Mérida, Yucatán, México. Highest spider density was recorded in August (total 118, adults 77), and lowest in May (total 7, adults 2). Spider density was significantly higher in isolated plants and lower in plants in a patch. Sex ratio (♀:♂) varied from 1:1.5 in April, to 1:1 in May, and to 1:0.1 in September. The dominant instar (both sexes) changed during the study. Throughout the study more spiders were recorded in ‘repose’ than performing any other activity. Foraging and feeding were more intense between July and September, when their prey, flower visitors, were more abundant. The number of spiders on plants varied spatially and temporally due to the combined effects of distance of the individual plant to the nearby forest, monthly precipitation, plant height, and number of panicles in anthesis. Forty-eight percent of the spiders were found living on plants with 20–30 panicles in anthesis (2% of the plant population). Most of the spiders (except for adult females) were found either below or above leaves. There were no significant differences in the distribution of most stadia respective to plant height. Positive significant correlations were found between the number of spiders and the abundance of floral visitors when the data were compared shifted-back one month, and between the number of spiders and the number of panicles in bloom when the data were compared shifted-back two months. When the abundance of spiders, floral visitors and number of panicles in bloom were correlated to monthly precipitation, we found a positive significant correlation for spider abundance when the data were compared shifted-back three months, a significant negative correlation for floral visitors when the data were compared shifted-back two months, and a nonsignificant correlation for the number of panicles in bloom, although both (panicles and floral visitors) peaked in May.