Yes, insects gain a lot of traction when plants are stressed. Note that my russian kale is shot by cabbage worm - IPM. That is actually very light damage compared to how it can be. Note also that the parsnip foliage is perfect. Never had a problem with it. I suspect that parsnip of all common garden crops is the closest to a wild progenitor. If it is host to a pest insect then the pest doesn't exist in this region, and after 350 years of parsnip in this region I think it would be around. Scott Nearing subsisted on parsnip as his primary dietary starch (lived to be a hundred, maybe as a consequence?). That is a standard I can't match!

I hope this plant does not get driven to extinction. It may be a blight on humanity, but this species is still very interesting from an academic perspective. You know, if you happen to get some of the sap on your skin, as horrible as the effects are, theoretically it can be okay as long as you immediately cover up the affected area and get into the dark, staying indoors for 2 days to make sure it does not get exposed to any sunlight (or artificial fluorescent lighting).

Your link is not working, so I cannot view the photos. But I'm taking a guess by the description alone...garlic mustard. Google it, and if that's what you have, get rid of it right away.

Alanis, one persons reaction to contact with a plant can be so different to someone elses, it's hard to say what caused your discomfort. There are specific plants that may cause a dermatitis in some, but yours could be something no one else might experience. You might try going inside and washing arms, face, hands with lots of warm soapy water when you've finished weeding and before you notice symptoms if that's possible. Maybe change your shirt too and put it in the laundry. I was encountering something picking wild berries one year that I never did identify (the offending native, not the berries :)) and a wipe with an alcohol pad from the first aid kit once back in the truck helped stop the itching and irritation. I'm fine with the euphorbias, monkshood, many of those commonly causing problems for others but I will never, ever open hellebore seed pods to extract the seeds with bare fingers again - that was painful for days.... But if you could post photos or at least tell us what is in that bed where you've found you have problems, we might be able to tell you the most likely candidate that you could then remove.