Comments on an article by R.L. Bevill, S.M. Louda and L.M. Stanforth in a 1999 issue of 'Conservation Biology,' on the use of insecticides to conserve the threatened Cirsium canescens. Appropriateness of insecticide as an option for management of endangered species; Ecological impact of the primary insecticide used by Bevill et al; Need for endangered species management to be based on a more ecological approach.