There seems to be a lot of panic about spiders -- most of whom are beneficial rather than poisonous -- and other insect problems. Look, scorpions vary a great deal in amount of venom and the body weight (or perhaps the closeness of the sting to a blood vessel) of the victim. Most scorpion bites are less of a problem than bee sting. If you are allergic to bee stings (or your cat is), then you will have more problem than someone else might.
Most spider bites are on the same level, but unlike the scorpion and the tarantula, such insects would rather retreat than attack. A few spider webs up near the ceiling and a few wolf spiders patrolling the floors at night are very beneficial to a house. They eat dust mites, book lice, and a wide variety of insects you don't even know you have. Spinners rarely come down from their webs, and only migrate when they are looking for a mate. Wolfs have territories, but like their dog-like namesakes, and will kill off competitors -- so you are unlikely to be buried in galloping nocturnal hordes on the floor. Cats are also very expert in killing them, which reduces their numbers to one or two, which is about right to keep the dust mites cleaned out of the floorboards or other little cracks and crevices about the house.
If you don't spray everything to death, preying mantises will periodically clean out the spider webs near the ceiling. Black widows have to be rooted out. Do some research on their preferred habitats and then think about your basement, attic, laundry room, the woodshed or garage, etc., and go hunting. They are solitary and secretive, like many truly poisonous things, and you have to be determined to find them.
The only problem with wolf spiders is that they carry their babies on their backs. this means that they will bring them into the house at night in a great mound on their backs while they hunt. If you have the misfortune to get up in the night and frighten one, she will turn to defend her dozens of babies, and the babies will scatter off her to hide until the battle between you is decided. If she cannot continue on her way (in which case, the babies remount her back and are carried back outside by morning), and you manage to kill her (they are rather hard to spray to death and rather large to squash without making you feel very icky), then the babies will remain hidden. Now you have perhaps 60 or 70 tiny little grass-mite sized spiders, and they do bite out of fear and lack of experience. a little like flea bites. Nothing serious, but not pleasant.
so if you see a spider that looks like it has a huge cancerous lump on its back, walk around it. Do not spray or swat at it. Let it go about its business and return to its nest outside. The babies will happily go about their business of eating each other until only a few remain. The remaining ones will try to get away from mama at a certain point in their development, because she will suddenly turn and eat them when they stop looking cute and helpless, and you are down to mama and perhaps one or two survivors, which the cats will reduce further, since they think playing with a wolf spider is the greatest thing invented since the mouse. Natural control -- natural selection.
As to nests of scorpions -- make sure you plaster all cracks and crevices between stone or concrete or tile foundations, floors, etc., since they love to sleep under damp stone. Force plaster between the floor and the skirting boards. Check around your house to be sure you don't have cracks between flagstone patios or porches near or against the house for them to emerge from. If you have stone walls or accent spots in your garden, dig to the base of them a ways and lay down poison, and then cover with dirt again. Your mistake was to build your houses on top of traditional scorpion nesting places (a similar problem with cockroaches and the travel paths of elephants). But since there's not much you can do about that, you can try to insulate your house from intrusion. If you don't give them much safe territory to make their nests, you will minimize the problem. If you can trap a few, take them to someone to identify in terms of venom load and agressiveness. You may find your scoprions are relatively benign.
When we lived in New Mexico, we did a "spring cleaning" by turning all the drawers out and checking for scorpion, tarantulas, and centipedes. In Texas, Spain, Portugal, Greece, and now in Israel, I continue this habit. I also continue the habit of checking my bedding (giving sheets and blankets a sort of flourish to shake up any intruders) and fluffing the pillows. In all these years, I have found a young wolf spider under a pillow or sheet only 3 times, and they are easily dumped onto the floor where they below -- the young ones sometimes get confused about territory until they get some experience, I have never been bitten by a scorpion (although I have seen many), and only twice -- on 2 successive nights -- been bitten on a finger in Spain by what was probably a spider -- painful swelling, but going down within a day or two with a simple tar-based ointment. I am 65 years old, and if all these insects were as pernicious and agressively dangerous as our primal fears would suggest, I should be a mass of bites by now.
Fleas, ticks, and various mites respond well to periodic treatment of my animals and their bedding, and the addition to a little amonia and chlorine to a simple floor shampoo. Only in a really bad year do I spray the house in any consistent manner. I do not clear out webs above 7 feet off the floor except when they become unsightly (and then I am careful not to kill the resident spiders, since they are part of my insect control brigades), and I do not kill a wolf unless she panics and drops her family, in which case I try to get them all. I kill only poisonous things near the house (scorpions, dangerous snakes). And I and my family have survived quite well. A few bites are a small price to pay for leaving nature alone as much as possible.
Just don't panic. Panic leads to over-poisoning, and that's not healthy for your animals OR for you and your children.
Hope this helps a little.