Thank you so very much OP for telling us that it is possible to destroy these monsters. Those hand held torches are a great idea and great way to start off, and it would be the ultimate investment to buy a large heavy duty propane flame thrower used for burning weeds and brush such as [link to www.flameengineering.com
Although those throwers arent military grade that shoot up to 20 feet, it's good enough to deal with the little critters. Few will have bazookas unless someone has kept a hidden weapon casche. Also, fire pits could be dug by the community and certain sections would be coordinated to be set a blaze when the invasion nears. I think that if the community is well coordinated with a plan B and C, we could have a good chance at stopping these things from further entering into our communitites.
Gold old fashioned dynamite and grenades lines at the borders of the communities will help us finish off a few of these super-luci-spiders, but since they will be in the thousands, we'll have to grap the torches and arrows set on fire or Molotov arrows, which could be bowed and arrowed into these superlucispiders, so archery is another great skill to have.
Good old fashioned Molotov spears and whaler harpoon are the last attempt.
Like you said OP, the element of fire will be the key in stopping these superlucispiders. Of course, the entire community will learn