Cyrtophora cicatrosa weaves a three-dimensional dome web and is commonly found in thorny bushes and cacti. The factors that could be responsible for this selection were studied, both by field observa¬tions and laboratory experiments. Structural re¬quirements in terms of space availability were found to be an important factor in the selection of the web site, though other factors could be significant. The relationship between C. cicatrosa and its immediate environment is discussed.