How Many Different Species Feeding on One Plant

does it take before the plant is no longer considered an invasive that must be removed from a natural area? I guess the 20 I've tabulated so far is not enough for the Friends of the Wissahickon, an organization to which I belonged for years, and which is supposedly dedicated to preserving it. Instead they proceed with their plans to eradicate Devil's Walkingstick at Carpenter's Woods and elsewhere in the Wissahickon. Birders, no matter how knowledgeable, have not been able to talk any sense into them.

My count of 20 is very conservative, based mainly on my occasional observations over the last few months. If I were to add in birds I've seen in previous years along with anecdotal evidence from other birders the total I'm sure would easily come to 50. If 50 different species feed on one plant should it really be eradicated? Does it really help the environment to remove such a well-used plant? I think you know my answer.

Seeing more species feeding today helped to fuel this tirade of mine. Again a Black-throated Blue, now pictured in header, fed for at least 15 minutes. He was joined on same group of plants by a Yellow-rumped Warbler(seen above), a Ruby-Crowned Kinglet and a Carolina Chickadee.

I'm not really sure what to make of the Friends of the Wissahickon. They've supported mountain bikes there though anyone who uses the area can see the horrible destruction they create. They remove plants that are obviously used by birds and blithely call them invasive. And yet they do accomplish some good. But you have to wonder? Is it now being run by bureaucrats too busy looking for grants to remember their real mission?