100 Species #63: Toadflax brocade

[urbpan]

Alexis found a pair of these caterpillars (Calophasia lunula) over by the main perennial beds.

I could simply call this the "toadflax moth caterpillar," but that would deprive us of the pretty and ornate common name "toadflax brocade." Toadflax is the weed in the snapdragon family that the caterpillar feeds on, and brocade is someone's fanciful idea of what the caterpillar's pattern looks like. This European insect was deliberately introduced to Canada in 1960, and to the west coast of the United States in 1968, to help control toadflax.

I don't mean to unduly criticize the agencies responsible for releasing this animal on a new continent, but it appears to me to be a poorly thought out decision. The caterpillar has a single host plant, so is unlikely to eliminate it. For example, gypsy moths can eat many different plants, and so huge numbers of them can actually have an effect on the ecosystem; if the toadflax brocade was to eat ALL the toadflax, they would quickly eat themselves to extinction. The adult moth feeds on the nectar of many plants including toadflax, meaning that the moth plays a role in pollinating and therefore sustaining the population of its caterpillar's host plant.

Since the larva only feeds on toadflax, which is itself an alien invasive, there doesn't seem to be any downside to the release of this non-native species in North America. In fact, you can apparently still get them if you would like to try to control toadflax with them.

This entry probably holds the record for the most dense usage of the word toadflax in the history of the internet.

Comments

[asakiyume.livejournal.com]

LOL your last statement.

I was just noticing the toadflax, both the yellow sort (which I call butter-and-eggs, but which I discovered last year is also known as toadflax) and the purple sort.

Using a predator or--what do we call it when it's a plant that's being predated... eaten? Well, anyway, using a species to control another species like this is never going to be 100 percent successful for the very reason you mention. But maybe the idea is just to reduce the population? ... I didn't realize toadflax was such a pest. I always just thought of it as a pretty wildflower. What does it get in the way of/ outcompete?

[urbpan.livejournal.com]

It looks like it's a bigger problem out west in the prairie states and provinces: http://www.dnr.state.mn.us/invasives/terrestrialplants/herbaceous/butterandeggs.html