Prohibit for worms

[Wolf River]

Since you live in Wisconsin, twice a year would be fine. Here where I live, I have to use it more often.
Apparently Levamisole is backordered or out of stock at the usual sites where I order it. I found this site in Kansas that has it in stock.
https://www.caprinesupply.com/levamisole-wormer.html

I found this at Tractor Supply. Also on Walmart and Ebay websites. Otherwise yes it is hard to find. Did ALOT of digging lol