I also live in the beautiful Mojave Desert.
(Did you get a chance to see Discovery's last landing at Edwards? Pretty amazing..)
But I don't like sharing my house with unwanted guests.
So I hired an exterminator to come in every so often to take care of the problem.
Ever since, I haven't seen one bug. Really.
The exterminator comes back every couple of months or so and I think it's some of the best money I ever spent.
They also know which chemicals to use so it won't be a problem for your kids and pets.
Roaches and other bugs can fit through the tiniest hairline cracks that you can barely even see.
You would almost have to tear out your cabinets and fixtures to seal up everything, and even then, in time it might separate and open up again.
Best to call a professional.
If you want to do it yourself, here's a method that is considered safe-
Boric acid was first registered in the US as an insecticide in 1948 for control of cockroaches, termites, fire ants, fleas, silverfish, and many other insects. It acts as a stomach poison affecting the insects' metabolism, and the dry powder is abrasive to the insects' exoskeleton.
Boric acid is generally considered to be safe to use in household kitchens to control cockroaches and ants. Homemade ant bait can be made by dissolving 1 teaspoon (5 mL) powdered boric acid and 10 teaspoons (50 mL) sugar into 2 cups (500 mL) of water; this mixture can then be absorbed into cotton balls which are left near ant trails. This reportedly will be carried back into the ants' nest, killing any ants that eat it, potentially destroying the entire colony.
Boric acid is also made into a paste or gel form. The paste or gel has attractants in it to attract insects; mostly cockroaches. It is convenient to use because you can simply put a small dab under sinks, counters, refrigerators, and stoves. The boric acid dehydrates the insects. It does it slowly and they don't realize they are in danger. One of the real benefits of using boric acid is that immunity can't be built up; since it works through dehydration. The insects take the bait back to the nest and one application can eliminate them for an entire year.
http://en.wikipedia.org/wiki/Boric_acid