What is a safe green termite spray for the ground before pouring a concrete slab?

Green termites are not problem, as they live in harmony with all beings. But the subterranean Formosan and similar buggers are a nuisance. But, by definition, any termiticide is toxic (to humans as well as the bugs).

Alternatives to chemical soil treatment are a 4" thick layer of 16 grit sand (can't be either smaller or larger) under the slab and extending 20" beyond on all sides (and in any utility trenches), which prevents tunneling, using SafeGuard EPS pre-treated sub-slab foam board, metal termite barriers between concrete and wood, and inspection zones to monitor for termite tunnels.

Borate-treated wood is also resistant to termites, but it's a water-soluble treatment and cannot be used in exterior applications.

Hi Jon -

Two things:

1. check out the GreenBuildingAdvisor.com Product Guide (http://www.greenbuildingadvisor.com/product-guide/cat/pest-control-devices). There are entries there for the basaltic termite barrier and the steel mesh that Robert describes. There are also entries for termite bait systems, ones that target termite activity in a more benign management system rather than a broad application.

2. I think one of the most knowledgeable persons on this topic is Mike Potter from the University of Kentucky's Extension Service. Check out his materials: http://www.ca.uky.edu/entomology/entfacts/ef605.asp and http://www.ca.uky.edu/entomology/dept/ipages/mpotter.asp.