2023 January 14 morning
Lymantria dispar
No recent observations or photographs to report. However, writes Jeremy Tatum, I
heard the tail-end of a news item on the radio today. I didn’t get all the details, but it was that the Government (fed. or prov.?) is going to engage this spring in a massive and widespread insecticide (Btk?) spraying program this spring to kill this moth.
In view of the disastrously low numbers of butterflies in the last few years, especially in
2022, which was almost a complete butterfly write-off in the spring, this is terrible news. Look at the annual butterfly report posted on this site on January 1 , 2023. See how many species of butterfly were totally missed. This spraying program will kill off the last of several species. Think about the Two-banded Grizzled (“Checkered”) Skipper.
Why is it that, although the Officials see huge outbreaks of L. dispar every year, no naturalists that I know of have ever seen this species, in any of its life stages (the ova and larvae are particularly conspicuous) in spite of deliberate targeted searches in locations where large outbreaks have been reported. Nor has the species ever been reported on Invert Alert in the 13 years in which it has been going.
More… Since writing the above, I have seen today’s (January 14) Times-Colonist.
There is an article on page A5. Spraying is to be in specific areas in Greater Victoria, Courtenay, Campbell River and Port Alberni between April 1 and June 30. In Greater Victoria , “treatments” will be in View Royal, Esquimalt, Colwood.
The Ministry of Forests says “It only affects spongy moth caterpillars, and is specific to their digestive systems. Scientific studies have concluded that it does not harm mammals, birds, fish, plants, reptiles, amphibians, bees or other insects”. I think that is a downright lie, and they know full well that it isn’t true. Btk is surely deadly to all caterpillars that feed on leaves. That includes caterpillars that feed on broadleaved trees, such as Lorquin’s Admiral, Tiger Swallowtails, Propertius Duskywing, Polyphemus Moth, Ceanothus Silk Moth – but of course the spray is bound to land on herbaceous plants, too, where it will be ingested by Two-banded Skippers, and all the rest.
There is an interesting and well-informed article about Spraying Btk for Spongy Moths in the Toronto area, which I recommend reading, at
https://www.returnofthenative.ca/about/jaggyblog/btk-spraying-kills-native-butterflies-mothsandimperilsnestlings#:~:text=It%20kills%20the%20caterpillars%20of,that’s%20on%20its%20host%20foliage
I believe Lymantria dispar does occur in the Toronto area. I have never heard of any being seen here other than by the Forestry Ministry.
