We examined the indirect effect of the herbicide glyphosate on field margin spider communities. Glyphosate was applied to two replicated (n = 8 per treatment) randomized field experiments over two years in 1997–1998. Spiders were sampled using a modified garden vac monthly from May–October in the following treatments: 1997 comprised 90g, 180g, & 360g active ingredient (a.i.) glyphosate ha⁻¹ treatments and an unsprayed control; 1998 comprised 360g, 720g and 1440g a.i. glyphosate ha⁻¹ treatments and an unsprayed control. We examined the indirect effect of glyphosate on the spider community using DECORANA (DCA), an indirect form of gradient analysis. We subjected DCA-derived Euclidean distances (one a measure of beta diversity and the other a measure of variability), to the scrutiny of a repeated measures ANOVA design. We found that species turnover and cluster variation did not differ significantly between treatments. We attribute the lack of any effect to a large number of common agricultural species which are never eliminated from a habitat, but are instead significantly reduced. Reduction rather than elimination does not cause the spider communities within these plots to turn over any faster than the control. However, like most other animal communities, the spider community did turn over and change in structure and composition through the season, regardless of treatment. Using Spearman rank correlations, we found that this within-season species turnover is related to the decline in vegetation height and the increase in percentage dead vegetation cover in the field margin.