We monitored populations of the stem weevil, Mecinus janthiniformis, the invasive alien weed Dalmatian toadflax (Linaria dalmatica) and other vegetation to document the impact of using M. janthiniformis as a biological control agent of L. dalmatica. Weevils were released in 2008 and again in 2014 after a wild fire. The results document increases and spread of weevil populations, decrease in Dalmatian toadflax and changes in cover of some vegetation classes. Resources in this dataset:Resource Title: Consolidated data dictionary. File Name: consolidated_HV_meta.csvResource Description: Description of variables in Condensed_HV data fileResource Software Recommended: Microsoft Excel,url: http://www.microsoft.com Resource Title: Consolidated data. File Name: consolidated_HV.csvResource Description: Condensed data for each site by year for plant size, weevil density, vegetation cover and meteorological data, 2008-2019.Resource Software Recommended: Microsoft Excel,url: http://www.microsoft.com Resource Title: Cover_2008 data dictionary. File Name: cover_2008_HV_meta.csvResource Description: description of variables in the file cover_2008_HVResource Software Recommended: Microsoft Excel,url: http://www.microsoft.com Resource Title: vegetation cover 2008. File Name: cover_2008_HV.csvResource Description: vegetation cover 2008-2011Resource Software Recommended: Microsoft Excel,url: http://www.microsoft.com Resource Title: vegetation cover 2013 data dictionary. File Name: cover_2013_HV_meta.csvResource Description: description of variables in the file cover_2013_HV, which contains vegetation cover 2013-2019Resource Title: vegetation cover 2013. File Name: cover_2013_HV.csvResource Description: vegetation cover 2013-2019Resource Software Recommended: Microsoft Excel,url: http://www.microsoft.com Resource Title: dissections 2009 data dictionary. File Name: dissections_2009_HV_meta.csvResource Description: Description of variables in the file dissections_2009_HV, containing dissections of toadflax stems 2009-2011Resource Software Recommended: Microsoft Excel,url: http://www.microsoft.com Resource Title: dissections 2009-2011. File Name: dissections_2009_HV.csvResource Description: Data from dissection of toadflax stems 2009-2011Resource Software Recommended: Microsoft Excel,url: http://www.microsoft.com Resource Title: dissections 2012 data dictionary. File Name: dissections_2012_HV_meta.csvResource Description: description of variables in the file dissections_2012_HV, containing data from dissections of toadflax stems 2012-2019Resource Title: dissections 2012-2019. File Name: dissections_2012_HV.csvResource Description: data from dissection of toadflax stems 2012-2019Resource Software Recommended: Microsoft Excel,url: http://www.microsoft.com Resource Title: stem_counts data dictionary. File Name: stem_counts_HV_meta.csvResource Description: description of variables in the file stem_counts_HV, which contains data on number of toadflax stems in 25 x 50 cm quadrats, 2008-2013Resource Software Recommended: Microsoft Excel,url: http://www.microsoft.com Resource Title: stem_counts. File Name: stem_counts_HV.csvResource Description: Number of toadflax stems in 25 x 50 cm quadrats, 2008-2013Resource Software Recommended: Microsoft Excel,url: http://www.microsoft.com Resource Title: stem_height data dictionary. File Name: stem_height_HV_meta.csvResource Description: description of variables in the file stem_height_HV.csv, which contains data on height of live Linaria dalmatica stems, 2008-2019Resource Software Recommended: Microsoft Excel,url: http://www.microsoft.com Resource Title: stem_height. File Name: stem_height_HV.csvResource Description: height of live stems of Linaria dalmatica, 2008-2019Resource Software Recommended: Microsoft Excel,url: http://www.microsoft.com