Tansy and Cinnabar Moth
There is a patch of what I believe to be Tansy and the young plants are covered with black and red caterpillars. Google provided this info http://www.ci.yachats.or.us/weeds/noxious weeds.htm My question is, should I leave the plants for the moths to continue their cycle or should I remove the plants immediately or later or ...?
Lane County Oregon invasive species
Leave the plants until you do not see caterpillars on them and then remove them. The moth larva are fantastic about moving on once they have consumed most of the seeds. Then if you can remove the plant or even snip of any new or old blooms, it will help reduce the tansy load for next year.