Tanacetum Vs. Jacobaea

Day 352: When people hear the word "tansy," they may be referring to plants of either genus, Tanacetum or Jacobaea. Both are toxic to livestock and contain volatile oils which may cause contact dermatitis in sensitive individuals, and both are considered invasive. The plants are easy to tell apart, especially when in bloom. Tanacetum vulgare (Common Tansy, top) has no ray flowers; Jacobaea vulgaris (aka Senecio jacobaea, Tansy Ragwort, bottom) does. The leaves are also distinctly different, although those of Tansy Ragwort can be highly variable, especially when young. The foliage of Common Tansy is fern-like; that of Tansy Ragwort is similar to that of radishes left too long in the garden, and forms a rosette. In Washington, the introduction of Cinnabar Moth (Tyria jacobaea) as a biological control has been fairly successful in reducing the occurrence of Tansy Ragwort, the caterpillars' primary food source. Once they have decimated an infestation of Ragwort, the caterpillars cease reproducing and therefore cannot become a secondary concern.

Biocontrol At Work

Day 262: Biocontrol of invasive species brings with it certain tactical issues and the need for long-sighted planning. If you introduce a predatory species to control the invasive, what is the possibility that the introduced species will develop into an unhealthy population? Will a species known to be attracted to the target invasive die out once its preferred host is gone, or will it shift to a new host and in doing so, become a problem in its own right? One of the best success stories I know is that of the Cinnabar Moth.

Cinnabar Moth larvae (Tyria jacobaeae caterpillars) are predatory on Tansy Ragwort (Jacobaea vulgaris, syn. Senecio jacobaea), rejecting most other plant species. They are hungry little buggers, and dozen of them can make short work of a three-foot tall specimen of Tansy in just a few hours. After feeding, they pupate and turn into adult Cinnabar Moths. The adults mate, but since they must lay their eggs on the host which the prior generation has consumed and that host is now absent, the critters have effectively eaten themselves out of house and home. It takes several years of the cycle repeating before the target is gone, but when there is no more food for the larvae, Cinnabar Moths disappear from the ecosystem as well. The larvae may even turn cannibalistic in the absence of the host, a self-limiting feature which makes up for the fact that both the caterpillars and the moths are distasteful to birds. A few may survive each year by shifting to a secondary host, but in the long term, they need a substantial volume of Tansy in order to reproduce effectively.

Allow Me To Introduce You

Day 300:  While we normally think of introduced species as a bad thing (case in point, the Tansy Ragwort shown in this photo), introduction of a species can sometimes be beneficial if managed wisely. The Cinnabar Moth (Tyria jacobaeae) was introduced to Washington in 1960 as a biological control for Tansy (Senecio jacobaea). You see, these little yellow-and-black buggers are very specialized. They are predatory on members of the Senecio family almost entirely to the exclusion of any other food. When that food source dries up (i.e., they eat themselves out of house and home), the caterpillars turn cannibalistic, thereby controlling their own population.

Paddling Tilton River Canyon

Day 298: I can't tell this story without prefacing it with a rant against Washington Department of Fish and Wildlife's extortionate fee system, because it very nearly ended this adventure before it could begin. When I arrived at the "public" boat ramp (I use the word "public" with tongue firmly in cheek), I came up against a sign advising me that if I wanted to launch my little craft, it would cost me an additional $7. The extra charge was tacked onto the $35 I'd paid for my Discover Pass, a permit which apparently only allows me to sit in my car in the parking lot looking wistfully at the water. This is the second time I've encountered a surcharge when I had nothing but a $20 in my purse and was not inclined to backtrack 10-30 miles to get change. In the first place, I resent having to have a Discover Pass and/or a Northwest Forest Pass to enter the woods half a mile on either side of my home. Fortunately, I am exempt from also having to purchase a National Parks pass, or I would be restricted entirely to pavement. Luckily, I was able to track down a semi-official person in the State Park campground who pointed me at the "day use" area where I could launch my kayak free of charge, although I'd have to wheel it about 300 yards. Wheel it I did, bump-bump-bump down the concrete steps at the swimming beach. That 300 yards was harder on my shoulders than the nine miles of kayaking which followed. As for WDFW, they have got the last cent out of me they'll ever see, except for my fishing licence. The Discover Pass is a masterpiece of false advertising, and I won't make the mistake of purchasing it again.

Now for the trip...I'd heard from one of our Park volunteers that the Tilton River Canyon was a fantastic kayak trip. I had seen it from above while walking the trail, and it did indeed look very enticing with its fern-covered walls and milky blue-green water. However, walking the trail gave me little sense of how far up the river I might be able to go. I expected to get quite a bit farther than I did. After being forced to get out and walk on three occasions, about two miles up, I hit the final obstacle: a small rapids I couldn't pass without portaging the 'yak, and I could see another larger one a tenth of a mile further on.

Upon turning back, my adventure took on a different mission when I noticed Spotted Knapweed (a "hit list" invasive) on the river bar. I had my GPSr with me, so I put in to take coordinates and photos so that I could report it to the Invasive Plant Council. While trying to determine the extent of the affected area, I also discovered Buddleia, Tansy Ragwort and acres of Japanese Knotweed. When I got home, I mapped the infestation. It's all on State Park land. The one good note I can inject here is that the Tansy was being devoured by Cinnabar Moth caterpillars, a biologic control introduced a decade or two ago which has had a good success rate (but maybe not here).

Because I'd had to turn back earlier than expected, I was feeling rather disappointed. I made a couple of loops around the island opposite the swimming beach, put in at a 20' x 30' knob of rock and dirt in the middle of the river and had lunch, and then decided to do it all over again! Back up to the rapids I went, and on the second pass, I was able to find a channel which didn't require getting out and dragging the 'yak through the shallows. I also saw some whopping big fish, and was kicking myself for having left the rod behind. Oh, well. I'll have another chance before my present Discover Pass expires, and now I know how to get around that stinking surcharge. $7 just to put a kayak in the water? Get real.