OUTSIDE: meet the new moth – same as the old moth


Known scientifically as the LDD moth, this invasive species has a new name and is expected to decrease in numbers, says columnist

A few weeks ago, this column mentioned that there were a lot of conferences going on right now; and the trend continues! I have just completed a three day forum with 57 speakers organized by the Invasive Species Center (based in Sault Ste. Marie). So much information to digest.

This forum was particularly interesting because the speakers came from all over North America, each a professional in their field of work with (or should I say against) invasive species. Yes, there are entire organizations and intense academic research projects into every aspect of these troublesome plants and insects.

One of the threads that connected so many topics was the cost of running these programs. For some species, there have been extensive investigations into the cost-benefits of managing a particular troublesome plant. The phragmites reed is that very large, heavy-headed bulrush seen in ditches and wetlands. For example, the Ontario Ministry of Transportation has earmarked $3 million for the management of Phrag this year. $3 million! That’s a lot of funding. How do they justify this? By learning from past mistakes.

MTO has a mandate to keep intersections clear of visual obstructions, and Phragmites reed can be a real visibility problem, especially at railroad crossings and on sharp turns along the roadway. The potential for fire is another threat (from dead, tightly growing woody stems) and if you have a ten mile long bonfire there is a huge cost to calling the fire trucks and shutting down a fire. highway to fight said fire.

And so MTO estimates that $3 million in Phragmites removal is the better bet than dealing with liability and fire damage claims. Smart move.

Another species that gets a lot of attention is the strangler vine, of which we have plenty in our area. When DSV (as it is affectionately called) sweeps in, there is a considerable loss of natural habitat as local birds, plants and the like are displaced or replaced by this vine.

For a decade we sprayed this plant with herbicide to kill it before it could completely take over a site. But this plant is tough, and seems to be developing resistance to the usual arsenal used against it. And it seems that the root system has been overlooked as a component of understanding this plant.

The DSV clod is huge and deep. So once it is established it is almost impossible to eradicate it. Other research has shown that as climate change brings in more carbon dioxide (with warmer air) and natural plant mass decreases, that “extra” available CO2 comes down to giving those plants invasive growth steroids.

In British Columbia, thousands of hectares of conifers have been killed by invasive beetles. All these now dead trees, when they were green and alive, acquired and retained carbon. This is not the case now and until a new forest grows (about 50 years) there is very little carbon sequestration.

Oh woe, oh darkness. Why am I attending these sessions?

On the other hand, there were some positive stories, such as the predicted decline of LDD moth in southern and central Ontario. Although the population cycle of this moth is well known, there has been growing concern over the past couple of years about the incredible population heights this caterpillar has aspired to. And spread. From a few places in southern Ontario to now lining the landscape and extending north past Sudbury.

The presence of bacteria and viruses that kill caterpillars has been positive in its negative effect on these caterpillars. Forecast models show a huge decline in these defoliating caterpillars for 2022.

And then we heard about The Nature Conservancy, based in the United States (not to be confused with Nature Conservancy Canada). This group worked closely with the American Entomology Society (AES) to make a major decision on what nickname to use to rename the gypsy moth. “Gypsy” is a derogatory name, and as this once obscure insect has become increasingly well known, there has been a movement to find a more pleasant name.

Most of us have slid into using the initials of its scientific name, changing all of our pamphlets, literature, and mindset to LDD. Not good enough, says AES. One of our many renaming rules states that the new common name cannot use the scientific name. Nor can it be a person’s name. Or its pejorative (as in “Poop floating around in your coffee”). The new name has to be neutral to the point of being ridiculous, and they succeeded!

The new common name that has been proposed (which will be voted on by the society for acceptance in early February) is (drum roll) sponge moth! Named for the appearance of its egg mass stuck to a tree trunk.

I don’t know about you, but sponge moth? The reason we changed from Pale Swallow to Dog Strangle Vine was to engage the mindset of the audience. At least make the enemy look threatening.

The things you learn on these forums! If you want to dig deeper, I understand that the Invasive Species Center will put many presentations on their YouTube, so be sure to visit their website to see the wide range of invasive species information now available.


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