This stuff here works great. I did the other stuff including Terro. Just like rhodydan said about Termidor, one spray around the foundation and ant problem was gone. I respray about every 2 years.
I've not seen more than a handful of scorpions in many years. It's not bad like Central Texas. Venomous spiders aren't much of a concern. If you buy a pump sprayer and some Tempo, you can give yourself a good defense against spiders. The stuff is non-toxic to humans and pets after it dries but is lethal to spiders and houseflies. It's a bit pricey, but a little goes a long ways.